[1]Patented June 18, 1946 2 t 4 O 2 . t l 7 6 UNITED STATES PATENT OFFICE 2,402,176 POLARI[ZED IELLUMINATI[ON Alvin M. Marks, Whitestone, Long Island, N.Y. Application November 16, 1938, Serial No. 240,608 14 Claims. (Cl. 88-65) 2 My invention relates to the iuumination of surfaces and is directed more particularly to the modiflea tion of light impinging on or reflected from surfaces in such manner as to eliminate or minimize glare when said surfa,ces are viewed 5 by the human eye or by photography or television. My invention further relates to illi@minating means adapted to transmit polarized light, and more speciflcally my invention relates to a light- 10 ing fixture so constructed that it transmits polarized light and non-polarized light. My invention further relates to a sheet polar- , izer and to various methods of producing the same, and to various modified forms of such sheet 15 polanzer s. Mrst with regard to the illiimination of surf aces: It is well recognized that, when a surface is seen by reflected light and particularly when the 20 source of light is positioned at the OPPosite side of the object viewed on said surface, the reflected light irnpinging upon the eye will ordinarily resuli iri more or less glare depending upon several factors, among which may be mentioned the Ught 25 absorbin g qualities of the surface, th6 character of said surface, the position of the source of light with reference to the surface and the eye, and the intensity of such light. In everyday life, these phenom ena manifest theniselves, for example 30 when a person is reading a book with the liw]@i positione d on the opposite side of the book from the eye and in substantial alignment so that the light impinging on the printed page is reflected directly to the eye. If the bgok has calendered 35 pages, it is praciically impossibie to see the print. Another example is found in the instance where a person seeks to view the grain of wood of a desk through a glass plate superimposed thereupon when the desk is positioned between the 40 observer and a window through which sunlight is streaming upon the desk top. In such instances, the reflected glare is so pronouiiced as to be almost bhnding. My experimentation and research in connec- 45 tion with these phenomena have led me to certain conclusions on whicb the present inv . ention is based. I have found that when, light is reflected from any insulating surface, the light reflected from the upper molecules of the surfe@ce, 50 t'lat is to say the upper layei-, is not appreciably affected by the nature of the material. By "insulating surface," I mean the superficial surface of material which is substantial.ly a non-conductor in the electrical sense. This includes me- 60 tallic or other electrically conductive bodies coated or covered by an insuiating fUm of oil, lacquer or the like. My observations have shown in this connection that when ordinary light strikes, for example, a glass surface, a large proportion of that portion of the beam which Is reflected from the plane of. the surface or by the surface layer. is polarized In a plaiie normal to the glass surface, while that portion of the light which penetrateg the surface is refracted thereby and transmitted to the deeper layers below the surface and there reflected and modifled to a great extent by the absorptive Properties of the material below the surface layer. If,the reflected beam and the refracted beam are at substantiauy ninetY degrees to one another, the reflected beam may be totally polarized in accordance with Brewster's law. At other -angles, however, the polarization of the reflected b eam is not complete. However, for the angles between say twenty degrees and sevent I y degrees to the normal to the surface viewed, a substantial fra6tion of the purely reflected light is plane polarized; that Is for ail angles at which surfaces are ordinarily viewed, a substantial fraction of plane polarized light comprises the hght reflected from the surface. In any event, if it be assumed that the surface viewed is a surface of a desk with a glass plate thereover, an incident beam of ordiiaary light impinging upon the exposed upper surface of the glass will be brbken up into two distinct beams, namely, a reflected beam and a refracted beam. The reflected beam wfll be substantially polarized in a vertical plane, while the refracted beam will pass through the glass plate and impinge upon the wooden table top which will reflect the @-aid refracted beam through the glass plate to the eye of the observer. As the absorption of the refracted beam by the grain of the wood is in readi]Y distinguishable degrees, the beam reflected from the wood surface will exhibit a marked contrast so that the grain of the wood may be readily seen. There is thus impinging upon the eye this latter contrasting beam and also the beam reflected from the glass surface and substantially polarized in a vertical plane, but inasmuch, in some circumstances, as the vertical.plane pol@r!zed reflected beam embodies materially greater intensity, the eye reacts mor@ pronoiincedly thereto and it is practically impossible to see the contrast in the reflected refracted beani. It has been heretofore suggested that reflective glare might be minimized through the. iiiilization of so-called "analyzers" in the form of spectacles or binoculars adapted to be worn by the observer
[2]2,402,176 3 or held In his hands in such a manner as to intercept the reflected beam directly before his eyes and after the beam has left the object to be viewed. I have observed through my researches, how5 ever, that if it is possible to substantially eliminate, prior to impingement on the @urface, the beam which would be reflected from the glass surface in the example given, that the other beam of contrasting character may be properly 10 and effectually observed without eyestrain and without the use of analyzers. The object of this invention, therefore, in a generic sense is to so modify light transmitted to a surface to be viewed as to substantially eliminate therefrom 1,5 the glare component of such light and thereby permit coritrast in said surface to be clearly observed without an analyzer. This I have found capable of accomplishment by dividing, ordinory light into two distinct components of plane PO- 20 larization at right angles to one another and elirninating therefrom the one plane polarized in a plane normal to the surface viewed and prior to Impinging of the light upon said surface. To g,ccomplish this I plane polarize the ligli@ prior 25 to permitting the same to Impinge upon the surface tci be viewed, so that only piane polarized light impinges upon and is - reflected from the object to be viewed. In practically carrying oiit the invention, 1 30 Interpose between a source of light and the object to be viewed a I polarizing medium which will plane polarize the beam in a plane including a ray in the beam and normal to a plane whicli passes through said ray and its geometric pio- 35 jection on said surface, so that when the beam impiiiges upoh the object, it will be divested of liglit in its plane of polarization normal to, and which would ordinarily be reflected by, the surfac6'or surface layer bf the objei3t and cause 40 a glare and thus I eliminate the purely reflected beam, while the beam of light in the former plane of polarization is refracted, penetrates the sur@ face Iayer, and Is transmitt ed to the lower layers and modified to a greater extent by the absorp- 4,5 tive properties of the material of such object, and is reflected thereby in a more or less dif - fused way not condu@ive to glare, but rather in a manner to give well deflned contrast between adjacent areas which differ.in absorptive ability. 50 This reflected diffused contrast-carrying beam is substantially unpolarized. Various apparatus may be employed in carrying outlhe present invention and In every instance polarization takes place prior to the im- 55 pingement of the beam on the object. The particular apparatus employed will of course depend upon the type of illumination desired, such, for example, as direct illumination as distinguished' from indirect illumination, in for example the 60 art of house lighting. The invention'is directed primarily to apparatus for carrying out the present invention, but it also includes the methods whereby this re- _ sult is achieved. 0i) With regard to illumination means for illuminating with polarized light: The problems of providing non-glare lighting and the benefits, of such non-,glare light have long been recognized. The potential dangers of 70 eye strain and sight difficulties brought about by reading in a glaring light are commonly recognized, and many attempts to provide a scientific light to Prevent such eye strain have been made. Commonly, such attempts to overcome tlil@50 76 4 problems have concemed themselves with diffusion of light and with light direction. But further scientific research has revealed that diffused light by no means solves the difficulty of glare and that the true solu'tion for providing a light that will enable reading without strain or tiring effects necessitates the use of polarized Hght. Polarized light, by Its physical nature and particularly when employed as I shall hereinafter set forth, provides an Ideal light which iuuminates without objectionable reflection and glare. But to provide polarized light it has been most convenient to employ polarizing means containing either a large single crystal or multiple crystals that- act, when properly aligned, to polarize the light directed therethrough. But such polarizing means are relatively expensive, and at Present are not being manufactured on a sufflcientlk large scale for mass production suitable for low cost illumination. I have conceived of a novel illuminating means whereby I obtain the desirable polarized light at such a range as is suitable for reading and simi-lar purposes and whereby T also obtain nonpolarized light in those ranges where polarization of light is not necessary. Further, my novel illuminating means provides indirect lighting effects which are extremely desirable for general Illuminating utflity. I have speciflcaby employed a multiplicity of layers of very thin Plastic material in such a way as to obtain a polarizer that for the flrst time makes possible the practical commercial use of the polarizing action of the multipletransparent layers known in the art. This polarizing medium comprising t]@e plurality of layers of thin plastic sheets united in close contact with each other Is an important element of my inventlion. It Is an object of my inven-tion to provide glarefree illumination. It is another objectof my invention to provide a novel non-glare illuminating means by appropriate polarization of the transmitted light. It is another object of my invention to provide a nov(@l illuminating means that transmits non-glare polarized light in radial directions and unpolarized light in substantially a vertical direction. It is another object of my invention to provide non-gl@re illuminating means that transmits only reflected light in radial directions through a polarizing means comprising a series of thin transparent plates. It is still another object of my invention to provide a novel indirect lighting lamp comprising a light source, means for directing light from this source on to reflecting surfaces, and means for directing that light from the r(@gecting surfaces through a series of thin transparent Plates at an angle of about thirty-three degrees to provide non-glare polarized light. It Is stir anotber object of my invention to provide a novel non-glare illuminating means by means of which reflected light is transmitted through multiple closely aligned transparent plastic plates. It is a further object of my invention to provide a non-glare light polarizing lamp having a reflector with a depolarizing surface for the purpose of increasing light transmission efficiencies. It is still a further object of my invention to provide a light polarizing lamp having a clear bulb light source, a reflector below such light source and a reflector of revolution above such light
[3]2,402,170 5 source so as to reflect rays radially through a sWtatlepolarizing medium, thus providing a field of radial non-glare illumination. It is another object of my invention to produce a non-glare light polarwng lamp having multiple reflectors belonging to the same family of parabolae. It Is still another object of my invention toproduce a radial polarizer compri6ing a multiplicity of very thin transparent sheets. It Is stfll another object of my Invention to produce a polarizer comprising a multiplicity of very thin plastic transparent sheets. It i@ a further objeet of my invention to produce a polarizer comprising from 15 to 30 thin plastic sheets. it is still a further object of my invention to produce a polarizer comprising from 15 to 30 thin plastic sh,eets having a thickness- of about .00088inch. It is still a further object of my invention to pr6duce a polarizer comprising from 15 to 30 thin plastic sheets having a thickness of .0015 inch or less. It is ' still a further object of my Invention to provide a polarizing unit having a predetermined angular position to effect the polarization of light directed normal to'the unit. It Is still a further object of my invention to provide a system of non-glare room illuminatioin adapted. to simultaneously direct properly polarized light onto vertical and horizontal surfaces of the room or objects within the room. It Is still a further object of MY invention to provide novel forms of multiple plate polarizing units. it Is still a further object of my Invention to provide a polarizer h%ving areas of sharply different indices of refraciion.. Flufther objects of MY ; invention will beca,me apparent from the description thereof herein se@t forth and from a consideration of the, &awings. The thin piastic sheets which comprise thle polarizer of my invention are preferably on the order of .0015 inch or less although they may run as thick as .004 inch. I prefer to use from 15 to -30 of th4@se plastic sheets of the thickness above referred to and to closely contact and sultably Join these sheets together to get such permanexit interfacial contact for proper polarizing resvlts. By employing thin plastic sheets on the order ()f .0015" or less, I get the following new and unexpected results. 1. Tow absorption of light: Because of the extreme thinness of plastic sheet little light is ab- 55 sorbed or lost during th I e transmission of the light through the polarizing medium. Inasmuch as the polarizing action of itself theoretically blocks out fifty per cent of the light, it is of gr6at importance that a maximum quantity oir #30 light be transmitted through the polarizing medium so as to actually obtain as close as possible to the maximum of fifty per cent of light. 2. Utilization of a multiplicity of thin films as above designeted has the further new and 66 novel result Df transmitting light without objectionable coloration iii'its passage: For example in the case of layers of rubber hydrochloride of a . thickness greater than that designated here, the use of multiple layers gives a.decided yellow tinge 70 to the transmitted light; whereas the emplo:yment of very thin films of the above ranges reduces the coloration to a riegligible amount. In this same connection, I have found that when films above the range I employ are used, 76 5 10 15 20 .. 25 30 35 40 45 60 6 there is such a scattering of the light within the films as to Interfere with clear vision therethrough and cause the blur and diffusion. Again, when a'film of the thickness -of my range is used, this scattering is reclueed to an amount that makes it relatively unnoticeable. As a further new and novel result of this device, I obtain a reflected beam of unusually high intensity. This Is because t e extremely layers have practically negligible absorption in the passage of light Into and out of the polarivang layers. Ms high intensitsr reflected beam of light is virtually colorless and very Mghly polarized. It also Is substantially close to :dfty per oent of th@ originally impinging beam. In contradistinction to this, when thick plates are used, there is considerable absorption of Ilght as it travels into and out of the layers so that the reflected beam is substantially weak@r than the reflected beam when very thirl layerc of the range I specify are used. This is because the path of light when my extremely thin plates are used Is infinitesimal compared to the path of the light in the thicker plates such as glass. 3. Fewer strains: By employing the extreme thinness preferably of .001511 or less, the strains which are often set up in plastic material are of such small dimension that the light transmftted therethrough. is ordinarily,- substantially unaffected. That is, if thicker plastic were used, th e strains would have a decided influence on the passage of the light through the strain area, but in the extremely thin polarization sheet employed, the strain areas are a negligible factor. These are points of Importance because it is to be remembered that because of the large number of such sheets used in combination, nameiy 15 to 30, if there were such detrimental factors of strain areas or absorption or refraction, the effect would be additiveiy aggregated to be a serious problem in the polarizer. 4. No biickling: By employing plastic sheets of the preferred thickness above set forth, I have solved another practical problem in connection With this pdlarizer. The polarizer is adapted to be employed in homes, often adjacent to a light source, such as a bulb, which means that there is a large amount of heat developed to which the plastic sheet polarizer is subjected. Because the plastic sheet polarizer is positioned In front of the light source, one side of the polarizer is subjected to a far greater amount of heat than the other side and thus there is substantially greater expansion on that side. which is in closest contact with the light and heat source than@ on the external sheets which are farthest from the light source. This relative expansion of different sheets is imdortant because the sheets are permanentl and positively secured to each other so @ y that if the differential expansion between the respective sheets.is too great, there will be a rupture of the union or a buckling that would seriously impair, if not destroy, the effective use of the plastic sheet polarizer. I have found that the preferred thickness range above referred to is such that the expansion between the respeetive sheets is Within the range that will prevent any separation between the component sheets and, further, is such that no buckling results under the heat conditions to which the plastic sheet polarizer is subjected. 5. Close and flat contact between the sheets: By employirlg the plastic sheets of the thickness above referred to, namely .0015" or less, I achieve the optimum condition of close and flat
[4]2,402,176 7 contact between the respective sheets. VVhen thicker sheets are employed I have found that the extremely close contact between the respective sheets is more Irregular and more easily disturbed than with the thin sheets which I em- 5 ploy. What I believe to be an important reason for this close contact is that in sheets of the extreme thinness that I employ, there is a certain tendency induced by electrostatic charges, because of which the very thin sheets are attracted 10 to each other and permanently maintafned in that close and flat contact. 6. Excellent light polarizing effects and light transmission: A further new result which I obtain by the use of the extremely thin sheets 15 above referred to is that I may use in combination from 15 to 30 sheets without detrimental light loss or light error and tWs number of sheets, namely 15 to 30, gives. practically perfect light polarizing effects and light transmission. 20 When very thin plastic material, such as cellulose acetate or Pliofilm, is employed, I have found that by stretching the plastic film so that it is permanently held in its Position in the lamp in a stretched condition, a higher transmis8ion can 25 be achieved. This applies to other elastic plastic materials. In this stretched condition, buckling due to heat expansion is avoided. When it is desired to have an air space between the respective layers, I may employ an ad- 30 hesive which may be in the nature of a thermoPlastic adhesive or a thermoadhesive or a material having a plasticizing and adhesive effect upon the respective layers. In order to secure the bond I may also. employ alternate layers of 35 thermoadhesive and alternate layers of nonthermoadhesive materials, in the case of the niaterials having the specified differences in the indexes of refraction. As an adhesive means for use in joining the re- 40 spective layers to obtain the proper air spacing between the layers for polarizing effects I may . also use preformed intermediate layers of thermoadhesive sheeting, that is preformed layers of thermoadhesive sheeting which are small in 45 area and operate to bond the respective layers one to the other. The thermoadhesive sheeting may be applied from a continuous strip which is cut by suitable cutting means and the cut area applied by a travelling applicator. In this way I .0 may obtain a predetermined spacing between the respective sheets so as to maintain the optimum spacing between the sheets. This preformed thermoadhesive sheet presents certain advantages over the above mentioned methods of bond-. ing by liquid adhesive in that it insures that there will be a minimum of spacing and that it holds this bonded area to a minimum. As will be noted, it is desirable that such bonded'area will be held to a minimum inasmuch as the total polarizing effect of the respective bonded plates depends up- 00 on the non-bonded areas. Alternately, I may employ as the bonding means a continuoi)s sheet of a@dhesive material having large stamped out areas, so that there rema-ins only small areas to effect the bonding of the respective adjacent 65 plates. The cellular structure thus resulting has the additional, advantage of being self -sealed against exterior conditions. The use of thes@e preformed adhesives insures a final polarizing me ans To which the plastic materials are unaffectecl by added Plasticizer or extraneous deleterious heatin g @ff ects. i p'iefer to effect a seal about the periphery, or ad'a6ent the periphery of Liy composite polar- 75 8 tzing plastic layers in'order to prevent the entrance between the respective layers of moisture or any deleterious influence which may disturb the desired polarizing effectiveness of the unit. This seal may be effected by simple heat and pressure means when thermoadhesive layers are employed, or a strip of added adhesive or adhesion inducing material may be employed about the periphery, which, together with ot without the pressure forms a neat seaj. Also it may be advisable to provide suitable sealing compounds to be applied after the said sheeting has been cut to size. This seal may be effected either by an added seahng material or, if the material of the composite plastic films is thermoplastic, the sealing may be effected by simply applying a heating means to obtain a flow to the edges. Farther the seal may be effected by the application of a plasticizer to the edges to cause the same flow of materials to obtain the sealing action. In order to maintain the plastic sheets In desired predetermined P(>sition, it s necessary to give them support. Although I have paxticularly spoken of the supporting means such as glass sheets externally placed with respect to the composite sheets, I may employ externally of these combined plastic sheets one or more supporting members comprising, for example, a radislly extending strip structure which acts to hold the composite sheets against sagging, or I may employ a supporting screen on the bottom Or on the top or both top and bottom of the composite sheets. The screens should be of such construction that they present ni aximum suPPort and minimum obstruction. When screens are used both on top and bottom, preferably I join the top and bottom screens with joining members such as staples to obtain a permanent rigid engagement between the two and hence form a secure unit. By the terin "screen" I mean not on.ly a wire mesh, but I intend to aPPly this temi broadly to any supporting structure that offers surface support. Another form Of SUPPort which, I may employ comprises Integrally laminated with the combined plastic sheets a suitably rigid radially extending strip member. This strip member may be of metal, such as wire, or it may be trans-, parent plastic material of proper shape. Such a reinforcing radial strip may be combined externally with the plates or integrai with them according to the method ofmanufacture desired. Previously I have discussed the use of a cut out sheet for effecting the separation of the respective composite plastic -sheets or layers. Such a cut away preformed sheet affords a certain stiffness or support and when a number of such cut away preformed sheets are employed to join the different layers, the stiffp-ess of these combined Preformed cut away sheets may afford sufficie I nt support without external means. In the event that it be desired to utilize said polarizing screen for polarizing ray!s directly normal to the plane of the poiarizer, the wire mesh support may be bent back and forth to a zig-zag corrugated shape so that the composite poli@rizing sheets will be held by the support at the proper angle to the impinging beam, i. e. about thirtythree degrees. In the case of the composite plastic films described in the pres,ent application I employ an atmosphere of an inert gas to preserve permanently the properties of the plastic material without deterioration. Flurther, the pressure of the Inert gas tends to preveni the volatilization of any vola-
[5]9 tfle liquids contained within the composite which would have a tendency to reduce polarization effects. In addition to the inert gas I empl6y a small amount of volatile solvent or plasticizer corresponding to that employed within the plkstic structure to effect a vapor pressure on such plastic so as to, maintain the contained solvent or Plasticizer within the composite structure and prevent its escape. The polarizing units described herein are intended for utilization not only with regard to artificial light sources but also with regard to natural illumination and may be employed in skylights, windows, or transparent walls or any simuar structures for transmitting natural light. The respective sealed polarizing units are also intended for employment in optical devices such a,s binoculars, telescopes, etc. These sealed polarizing units, especially of the type employing the acid iodo alkaloid compounds contained in the sealed transparent enclosures, are intended for use in optical instruments, and wherever the factor of long life and permanency is essential. They inay be particularly employed in such structures where there is sufflcient provision for the added space required, and may be of particular advantage on projection devices where intense beams of light tend to cause the rapid deterioration of the polarizing structure. The description of the drawings follows: In the drawings, ngure I is a cross-section of a lamp adapted to produce polarized light constructed in accordance with my invention, the lamp being positioned on a table with a book within the region of the polarized light thrown off by the lamp. Figure 2 is a cross-section of a polarizing unit of my invention comprising two extemal thin plates of glass and multipje layers of plastic material pressed therebetween. Fdgure 3 is a plan @iew of one of the polarizing plates of my invention in the form of a disc with spots or gobs of thermoadhesive on the face thereof to effect its firm adhesion to adjacently positioned thin plastic discs. Figure 4 is a perspective of a modified form of niy invention showing a lamp adapted to be positioned on the ceiling of a room, the polarizing plates being there placed above the light source, the po!Arized ligbt being thrown on to the ceiling a,nd reflected down into the room. Figure 5 is a cross section of a polarizing means of my invention comprising multiple layers of plastic material with certain spaces between the layers to produce polarizing effects. Mgure 6 is a cross section of a modified form of a polarizing means in which I employ multiple sharply defined layers of material, alternate layers being of low density and high density material so that each layer repr6sents a marked diff@rence in the index of refraction. ]@igure 7 is a diagrammatic view showing the manner in which I apply to a plastic material, adhesive or adhering means in spot staggered relationship. Mgure . 8 is a plan view of plastic material showing the spot. staggered position of the adhesive upon the plastic. Mgure 9 is a cross section of a polarizing unit of my invention in which I provide a continuous composite plastic polarizing fllm woiind about racks in a predetermined angular relation to produce polarization of light passing through the unit. 2,402,176 10 Flgure 10 is a cross section taken along the line 10-10 of Mgure 9. . Mgure 11 is a cross section of a polarizing means of myinventioii comprising a plastic material containing a multiplicity of air bubbles which have been flattened down by pressure on the plastic mass. Figure 12 is a cross section of the modified polarizing means of my invention comprising 10 layers of plastic iraaterial with intermediate layers of adhesive con@;aining air bubbles which have been fiattened out for polarizing purposes. Figure 13 is a cross-section of a polarizing unit adapted to polarize light directed substantially 15 normal to the su@f ace thereof. Mgure 14 is a cross-section of an illumindtion means comprising prisms for directing light from a source through a polarizing means. Figure 15 is a means for Providing glare-free 20 illumination in the form of selectively polarized light adapted to illuminate both horizontal and vertical surfaces from a single source. Figure 16 is a diagrammatic showing of a system of general room illumination adapted to pro2.1 vide low intensity light and glare-free illiimination of vertical and horizontal surfaces simultaneously. Figiiie 17 is a cut-away perspective showing a modified form of polarizing. means of my inven3o tion comprising an - assembly - of i Dined plastic strips properly positioned to polarize light directed nornially to the surface thereof.' Mgures 18 and 19 are; diagrammatic views showing the manner in Which light is trans3.5 niitted to an object according to different principles, Mgure 18 showing conventional methods and Figure 19 sh6wing the method according to this Invention. Figures 20, 21 and 22 show, apparatus embody40 ing the present invention for carrying out the method illustrated in Pigure 19. In these figures an appropriate -refiector and associated parts are shown in section' Mgure 23 is a plan section on the line T"-T 4.5 of Flgure 22. Figure 24 is a pers,-oective section of a structure similar to that shown in Figure 20, but with greater spacing between the polarizina. element and a diffusing plate than in the corresponding 50 parts in Mgure 20. Mgure 25 shows the manner in which a pair of lamps, such as shown in Mgure 20, may be arranged to simultaneously illuminate a picture such, for example, as an oil pairiting in order to 65 obtain satisfactory illumination of a relatively large surface uniformly. Figure 26 Is a fragmental view of a composite plate which I may employ in carrying out the present invention and which also constitutes 60 part of this invention. Mgure 27 is an elevation showing the present invention as incorporated in a direct lighting system as in the previous views, but showing direct lighting in all radial, directions. 65 Flgure 28 is a front elevation of another embodiment of t'.Iie present invention as incorporated in a direct Iighting system. Mgure 29 is a section on the line 13-13 of Flgure 12. 70 Mgure 30 illustrates an indirect lighting fixture embodying the present inventiori in elevation. Mgure 31 is a diagrammatic plan view of the polarizing member used In the structure of Fig75 ure 30.
[6]2,40,9,17,8 Mgure 32 shows diagrammatically another. form of indirect lighting fixture in central section. Mgure 33 shows diagraminatically another way in which a light beam may be manipiilated in a structure of the general character shown in Figure 16. Flgure 34'is a cross-section of a modifled lamp adapted to provide polarized light according to my invention. 10 Flgure 35 is a plan view of the polarizing composite plate assembly in th6 form of a disk which may be used as the polarizing element in Mgure 34. Mgure 36 is a cross-section of a modifled form 15 of a composite polarizer In combination wlth light directing means. Referring now more si@eciflcally to the drawings, in Flgure@ 1 is shown a lamp base I resting on a swtable support. From the base I of the 20 lamp there extends a hol low column 2 within which is contained a wire 3 carrying the source of electricity, the control of the electricity being effected by the switch 4. The wire 3 terminates in a socket 5 in which is placed a bulb 6 which 25 is preferably a clear lamp having a suitable wattage. The base of the lamp i is surrounded by the sbield 7 which effectively blocks any transmission of direct light through the p(>larizing plates. The inside surface 8 of the shield 7 pref- 50 erably has a smoo'th metallic reflecting coating. The column 2 terminates in a flange IO which co(>perates with a similarly ab'ove p6sitioned flange I I to firmly grip the polarizing means. The polarizing means comprises a series of -.35 plates 12, preferably 15 to 30 in number. One of these plates is shown in the plan view of Mgure 3. The multiple polarizing plates superimposed one upon the other are of such shape as to conform with the shape of the exterior of the laMP 40 and to intercept completely all light thrown down by the reflectors of the lamp. As has been shown, these polarizing plates are grasped at their inner edge by the flanges IO and I I and they are flrmly held at thdir periphery 45 by the flange 15 secured by the nut and screw arrangement 16 tG the reflector shade 17. The reflector shade 17 has preferably an interior depolarizing reflecting surface 18 which somewhat diffusively reflects the light thrown upon it by 50 th ' e clear bulb 6. The shade 17 may be metal, plastic or any suitable material. The reflector shade i7 is so angularly positioned with respect to the polarizing plates 12 that it diffusively reflects the light derived fr6m the bulb light source 55 6 down through the plates at an angle on the order of thirty-three degrees. The composite plastic sheet polarizer polarizes every beam of direct or indirect light that passes through it at the proper angle from any point 50 iii the lamp enclosure, whereas the conventional polarizer of herapathite crystal or the hke main-. tained in position will not polarize all the light in the proper planes when radially directed rays are used. or, At the top of the lamp shade is a cut out section 20 extending from the point 21 to the point 22. Through this cut out section non-polarized light may be directly thrown from the bulb 6 on to the ceiiing for general illumination purposes. The 70 lines 24 indicate the rays of light thrown from the reflecting surface 18 down through the multiple transparent plates 12. These rays of light 24 travel through the polarizing plates 22 at an 12 are polarized thereby. rhe book 25 is thus Illuminated by polarized light and the reader thereof is subjected to substantially no glare or eye strain. The rang6 of polarized light extends from the point 26 to the point 27. The light thrown down directly by the reflecting surfaces 3'0 at the top of the la;mp does not travel through the polarizing me4ns at the proper angle and, thorefore, Is not polarized, and this range of non-polarized light is shown below the lamp. Although I particularly set forth the light polarizing effects with respect to one side of the 1 lamp, it is to be understood that these effects are equally applicable with respect to the corresponding range on all sides of the lamp, there being, as indicated, a range of polarized light in the area indicated and a range of non-polarized light directly below the lamp in the area indicated. I further may provide on this lamp or for use on floor lamps or a desk lamp, means for adjusting the height of the lamp so that I may obtain the optimum angle for the polarization effect. This optimum angle is when the object to be viewed is at a thirtytwo degree angle with respect to the light source. I thus provide means for at all times making use of the valuable optimum polarizing effects in lamps carrying these polarizing mediums. In Flgure 2 I show a polarizing means comprising thin glass plates 35 and 36 between which are positioned thin plates or layers of plastic material 37. The plastic plates rnay be held to each other and between the glass plates by means of the clamps 38 and 39 with the flanges 40 and 41. If desired, only a single glass plate 35 may be employed at the top of the series of plates, and the remaining plates may be of plastic material. Flurther, only the bottom plate 36 may be,of glass with the remaining plates of plastic material. In Mgure 3 I show a means for securing enhanced adhesion between the respective plates. It is essential that these respective plates be closely held one to the other and securely maintained in this position with a definite but minimum space between the faces of the plates. Although this may be effected by the use of clamps alone, I have further found that superior results may be obtained when I additionally spot the Plate 12 with added thermoadhesive globules 45. As can be seen the globules 45 are spaced one from the other at suitable intervals over the surface of the plastic polarizing plate 12. Vvhen the proper number of plates have been so coated, they are superimposed one upon the other and pressed under heat. The heat activates the thermoadhesive and causes it to flow to flrmly secure itself to the adjacently positioned plates. The heit is not such as will impair the physical structure of the plates nor affect their surfaces. The use of this particular combining means for the plates as set forth effects certain new and unexpected results. First, it maintains a perinanent spaced positioning of the plates with respect to one another without external clamping means. Secondly, it insures a firm adhesion of the, plates one to the other without too great a spacing apart of the plates. That is, the small amount of added thermoadhesive spreads itself so that the adhesive hes in the form of extremely thin spot layers over certain portions of the plate. Thirdly, the adhesion is effected without impairing the optical properties of the plates which affect the polarizing of the light transmitted therethrough. angle of approximately thirty-three degrees and To Fourthly, the area covered by the thermo-ad-
[7]13 hesive Is only a small portion of the total surface area of the plate, and, therefore, the polarlzing effect of the plates is not blocked by the thermo-adhesive. In Figure 4, which is a modification of my invention, I shgw a polarizing lamp in the form of a ceiling flxture. I show a base 60 secured to the ceiling by suitable fixing means 51. In the base 50 there is placed the bulb or li.aht source 32 surrounded by the reflecting thield 53. A rim B4 supported by suitable chains 55 and 56 holds shade 57 with an interior preferably depolarizing .reflecting coating 58 which diffusively reflects the light from the,light source 52 through thepolarizing means 59, which comprises multiple plates of thfn plastic material closely superimposed and held one to the other. In the shade 57 is a cut out section 60 through which the light may be directly transmitted from the light source 32 to the room below. Certain of the light from the light source 52 is thrown on to the reflecting surfaces 38 and from them reflected through the polarizing means 59 to the ceiling 62. When the light travels in the angles indicated by the dotted lines, it provides th6 range of polarizing light @Lnd non-p olarized light as described before with reference to the table lamp. The Polarized light is -reflected by the ceiling 62, which should have a plain or preferably diffusin.- metallic reflecting surface, to the room below providing areas 64 of polarized light. The angles of the illuminating rays shown are purely schematic and do not necessarily limit the angles which may be employed. It is to be noted that the iinportant feature of my invention is that in a suitable lamp fixture I direct aU light to be polarized from a suitable light source such as a @,bulb to reflecting members which are so positioned as to reflect the light thrown thereon through a polarizing means COMprising a multiplicity of plates of tWn plastic material at a critical angle which effects the Polarization of the reflected light and provides a desirable range of polarized light at a suitable distance from the lamp. The polarizing means Of r@ly invention, in addition to beirig effective for the purposes set forth, is remarkably inexpen-, sive in comparison with the polarizing means commonly employed at present. Thus, in lieu of providing relatively expensive vehicles for carefully oriented polarizing crystals, I employ about 15 to 30 very tliin plates or discs of plas c material closely clamped on to the other and positioned at such an angle with respect to the reflected light as to provide prop@er polarization of the light. The plates of plastic niaterial may be of a maxi2num thickness on the order of fovr-thousandths of an inch. The preferred range is .0015 iuch or less. A good thickness is about .00088 inch. I have found that thispolarizing nieans comptising multiple plastic layers reduces the glare three times to 10 times depending on the angle of projection of the beam. Referring now niore specifically to the drawings,'in Mgme @ T show multiple layers 70 Of suitable plastic material such as a cellulosic derivative, a synthetic resin, rubber, rubber substitutes, rubber balide or rubber hydrohalide derivatives; vinyl acetate; acrylates and methaerylate, such as methyl methacrylate; cehulosic cOmpounds such as cellulose nitrate, cellulose acetate, cenulose hydrate and cellulose ethers, such as ethyl or benzyl cellulose; urea formaldehyde and phenol formaldehyde condensation products; 2,402,17e 14 as glyptal resins; and similar transparent resins and plastics. The layers 70 are joined by spots 71 of adhesive or of plasticizer. The plasticizer is one suitably selected to effect a softening of r) the plastic niaterial 70 and the ad acent plastic material so as to effectively secure such layers together in a particular spot. The spot adhesion of the adjacent layers produces air spaces 72 which are essential for polarizing effects. The 10 polgrization is effected by the light rays such as 73 passing first through the plastic layers 70 and being bent towards normal by the refraction in this layer and then by the same light ray striking the air space whereupon it bends away from 15 the normal as diagrammatically illustrated in this figure. After passing through the air'space, the light ray strikes the next adjacent plastic layer and part is reflected a@ shownby th6 arrow in the drawing and part is again refracted bending 20 the ray towards the ndnnal; this path is pursued down through the subsequent layers and air spaces so that the light is polarized as it passes through this composite of plastic layers and air spaces. It is desirable that the spacings of the adhesion 25 inducing means between the respective adjacent layers be so spaced that a substantial portion of the light rays passing through the composite passes through at least about flfteen layers, of plastic -,material and the corresponding air spaces. 3( In this way, proper polarization is effected. In Mgure 6 1 have shown a modifleation of my composite layer polariz6d means wherein layer 75 comprises a plastic having a relatively high Index of refraction as for example a resin or cel35 lulose plastic containing a powdered glass. The @lass may be lead glasg and be p@ssed in two forms: (1) relatively large, preferably thin flat, plates of circular or other shape; (2) particles of submicroscopic dimension, such as may be o-b40 tained in the well known manner by fine grinding and then separation of the smaller particles by colloidal suspension, and by centrifuge or decanting. In the case of this structure the multiple plastic layeirs need not be used since these 45 embedded flat particles of themselves act as the dense layers. In this case the incorporated submicroscopic particles are such as to opticary merge with the plastic base, and result in a compound material having as a, resultant, a higher 50,index. Adjacentlay@r76isalayerhavingarelatively lower index of refraction and this layer may be cellulose acetate. For example, the index of refraction of the layer 75 may be on the order of 1.7 and the index of refraction of the r)5 layer 76 which is of cellulose acetate will be about 1.49' The difference in indices of refraction of adjacent layers should be at least .2. Layer 75 and layer 76 are prefei-ably secured to each other by a suitable adhesive 77. If the layers 75 and 60 76 are by nature such as may be joined simply by heat and/or pressurei then an added adhesive is not necessary; but if they are not an adhesive -.by nature th6n an adhesive should be employed to maintain them in desired close contact. 65 Employing adjacent layers of altemate Wgh and low index'refraction materials, the lights rays passing therethrough are polarized in acdordance with the flxed principles set forth above inconnection with polarization shown in Ogure 5., @ 70 In Flgure 7 I show an apparatus for forming on plastic layers the staggered spots of adhesive which are essential for the formation of a polar@. ized means such as is shown in Mure 5. Here a roll of plastic material 80 mounted on a roll 81 glyceral phthalate resins, more commonly known 75 'is unwound and PUlled over a roll 82.. Cooperst-
[8]2,402,176 15 ing wlth said roll 82 Is a drum 83 rotated In the direction Indicated by the arrow. On the drum 83 are mounted applicator segments 84 arranged in staggered relation on said drum 83. Said applicator segments 84 are coated with adhesion r) inducing substELnees from the roll 85 which receives its supply from the rotating drum 86, mounted to rotate in a tank containing adhesion inducing substance 87. 1 After the respective layers of plastic material 80 are coated with stag- 10 gered spots of adhesive 87, they pass beneath the pressing rolls 90 and 91 and the pressure from such Pressure rolls causes the lamination of the @urface layers of plastic material containing staggered spots of adhesive on their surfaces. The 15 arrangement of the spots of adhesive 87 on the plastic layer 80 is shown in Figure 8. When a multiplicity of plastic sheets are ernployed to make the polarizer, it is important that the plastic not contain,such large quantities 20 of plasticizers or solvents as would tend to physically join adjacent sheet faces. As stated above, it is essential for the obtaining of 'the polarization effect that there be sharp lin6s of demarkation between the rpspective faces and that there 25 be a certain spacing therebetween which, al- . though minute, must be deflnite. For this reason, when I employ sheets such as cellulose acetate, it is important that the celluiose acetate sheets contain a relatively small amount of plas- 30 ticizer so as to prevent any molecular contact or actual interfacial adhesion. iri Mgure 9 I show a polarizing unit comprising an external transparent casing I 00 in which are positioned fixed rods I 0 1 and movable rods 35 102 which movable rods are held under downwardly exerted pressure by the springs 103. Movable rods 102 are mounted on shafts 104 which are slidably mounted in brackets 105. Multiple layers of plastic material 107 comprising a po- 40 larizing means of ihy invention, such as set forth in Fligures 5 and 6 described above, is wound over the flxed rods IO 1 and movable rods 102 as shown. The downward compression exerted by the spring 103 on the movable rods 102 maintains the com-. 415 posite polarizing film 107 in a taut. condition and positions it in predetermined angles with respect to the transparent casing 100. The light to be polarized enters through either side of the casing I 00 in accordance with the utility of the unit and 5( passes through the composite polarizing film 107 striking the composite film at such a predetermined angle that the light is polarized during its transmission therethrough. It is to be noted that the rods 101 and 102 are opaque inasmuch 55 as if these rods were trarisparent the- light travelling therethrough would not be polarized because it would not impinge the polarizing composite sheet 107 at the proper angle. Therefore, all light which travels through the unit is polar- 60 ized by the polarizing fllm 107 in its optimum polarizing angular position. The movable rods 102, forced downward by suitable depressing devices, are of particular utility inasmuch as the polarizing means 107 comprises a plurality of layers of plastic material. There normally would be a certain tendency for this so extended layer to stretch and therefore sag. This would impair it@ polarizing property inasriiuch as the composite would then be improperly 70 angularly positioned with respect to the light to be polarized. Further, the adhesive or plasticizer that joins the respective.layers of the eomposite fllm might in time lose its effectiveness and thi-s would further the tendency of the respective com-, 75 16 ponent layers of the polarlzing sheet to separate. This is properly counteracted, however, b3t theconstant pressure exerted by the movable rods 102 which. maintain the respective layers in close relationship and which acts to correct any tendency to separate. Although conceivably I could exert this pressure at the respective ends of the polarizing film 107, I have obtained miaasurably superior results by employing the movable rods under pressure through the device as shown, since In this way I have obtained a uniform and constant pressure on aU points of the plastic film with no impairment of this pressure by the sectional contact of the polarizing Mm with the rods 107 such as would be experienced If the pressure were applied at the ends of the fllm Instead of at intermediate points thereof as shown here. In the walls of the polarizipg unit I provide recesses I I 0 carrying an absorbent material I I I which contains suitable volatilizing substance iadapted t6 maintain the polarizing, film 107 in a proper condition. This volatilizing material may, for example, be a solvent or plasticizer adapted to either maintain the originally incorporated solvent or plasticizer in the film by the vapor pressure exerted by this added solvent or plasticizer or its acticin may consist in replacing any solvent or plasticizer that may escapb from the film. Similarly, the volatilizing material contained in, the @bsorbent material I I I may be of any desired material such as iodine which will maintain in or replace in the polarizing film certain essential substances to prevent decomposition thereof. When using this added volatilizing material, preferably the polarizing unii and its casing I 00 are hermetically sealed. In Figure 11 I show aplastic material I IS contairi-ing therein a multiplicity of bubbles I 16. These bubbles II 6 are incorporated in the plastic material II 5 by mixing air or suitable gas with the plastic or by employing the vapor given off by volatilization of any solvent which will cause such bubbles in the plastic mix. The plastic mix containing the air bubbles may be pubjected to agitation to reduce the air bubbles to very small size. After a sufficient number of such bubbles I IS Are formed in the plastic II 5, pressure is exerted on the plastic I IS in the direction indicated by -the arrows 117. Thus pressure flattens out the bubbles I I 6 until they assume the elongated and flattened shape shown,in thig flgure whereupon in combination with the plastic II 5 they form a po@ larizingdevice. Itispreferredthattherebesufflcient numbers of these flattened bubbles in the plastic material ;so that light rays passing through will pass through a multiplicity of these bubbles so that the proper polarizing effects are obtained. The path of such light and the polaring of the light rays is diagrammatically shown in this figure. In Figure 12 I show a modified form of my polarizing means comprising.transparent layers 120 which may be of plastic material joined by adhesive means 121 containing bu@bbles 122. The bubbles may be of aii@, gas or may result from I the use of volatile liquids. As in the I)olar' izing means previously described, these air bubbles are flattened out by the pressure applied in the direction indicated by the arrows 125, which pressure causes them to assume the elongated flattened shape. 'khe Iight rays passing through the respective layers, 120 which have a relatively high index and then through thb elongbted bubbles which have a relatively low iiidex refraction ore
[9]17 polarized as Indicated diagranunatically in this f4me. It is to be notedthat the various modifications I have shown relate to specific means for carrying out the formation of a polarizing structure in which Ught travels alternatively through areas of high index of refraction and low index of refraction. Referring now more speciflcahy to.Vigure 13, I shcfw a polarizing unit adapted to polarize light directed substantiauy normauy incident thereon, which polarizing unit is adapted to be employed for polarizing -giinlight or artificial light,'as for example in skylights or building constructions generally. The polarizing action is effected by the composite fUm 131 which comprises a multiplicity of thin plastic fibns 134 joined together by adhesion inducing meons such as solvent or cement or preformed plastic 135. To properly position this eomposite polarwng sheet, I place it between blocks 132 and 133 which are approximately triangular in section and wliich maintain the composite fUm permanently at substantially a thirtythree degree. angle with respect to the normal SO that light passing therethrough froxh the surface 130 of the unit is polarized. The 6ntite mass forms 9, solid unit by virtue of the joints between the surface 130 and the blc>cks 132 and the polarizer 13 1. AR elements being transparent, the entire unit is transparent. For absorbing the reflected light from the uppermost surface of the composite polarized sheet, I may provide dark absorbent areas, as for example, in the form of a dark sheet which bisects the triangular block 132 and extends from midway between the base of that block to midway between the base of the triangle. This sheet is optional and may be used for increased efficiency. In Mgure 14 I show a means for directing Polarized light in a particular desired angular range to a horizontal surface. The light is derived from any suitable Hght source 140 and. is directed by suitably aligned prisms 141 which may be embossed in a glass or suitable plastic molded surface. The prisms are so positioned and constructed as fo direct the light from the light source 140 in substantially parallel directions@ at an angle of approximately 33' to the horizontal surface 142. This parallel beam, of course, is understood to be parallel only in a particular plane pawing through the vertical axis 143 and said parallel beams are distributed radially In particular planes or aU planes about this vertical@ axis. I direct these beams by means of the prisms at an angle of approximately 33'. because light so directed onto a horizontal surface and polarized during its travel in the manner to be described Will provide substantially glare-free illumination for such horizontal surface regardless of the position of the observer. For the light which travels upwardly from the light source 130, I 13,rovide a suitable reflecting surface 144 which Is of such curvature as to direct hght therefrom through the light directing prisms 14 1. Although I have shown this reflector as being level with the uppermost prism, for best results I prefer that this reflector be spaced a certoin distance above the uppermost prism and it directs light from the source 140 through such space without the aid of the prisms 14 1, or this reflector may be spherical with its center coincident with the fhament and thus act to redirect light thrown upwardly back to the prisms. .21402,178 is vide a polarizing means 146 which Is the conventi6nal polarizer of the prior art, namely any suitable sheet polarizer containing, for example, oriented polaiizing crystals. The polarizing axis of polarizer 146 is such that the axis fohows concentric circles about the common vertical axis, such construction having the effect of polarizing 6very ray in a lilane normal to the plane of incidence. The dir6etion of polariza10 tion of the light beams is indicated by the dots 147 which i,ndicate that the plane of polarization of the light is at right angles to the plane of the drawing of Mgure 14. For the light from the light source 140 which is initially properly di15 rected, I provide a plane transparent ring 148 which permits the passage of the light without, bending it. Referring now to Figure 15, I show a particular means for providing polarized 'illumination in 20 all radial directions from a central sour6e so as to provide simultaneous glarefree irumination for objects having both vertical and horizontal siirfaces. To effect tWs result, it is necessary that light directed onto- the vertical and hori25 zontal surfaces be respectively polarized in different planes in its path from the source of illuniination. By way of illustrating the vertical surfaces which are to be iuuminated, I show a picture 150 and a ray 151 polarized in a vertical 30 plane as indicated at 152 impinging upon that picture to provide a glare-free iuumination. I also show a. horizontal surface such as a table or a floor 153 and a ceiling 154 and rays 155 and i 56 respectively impinging on these r6spective sur35, faces, said rays 155 and 156 being polarized in a plane which is normal to their plane of incidence as shown by tbe dots 157-158 respectively. To provide this dual glare-free illumination by means of properly positioned polarized media, 40 cooperating with directed beams of light, I have shown by way of illustration, a fixture in which I provide a light source 160 surrounded by a sheet polarizer containing aligned therapathite crysta@ls or other suitable polarizers. The rays 45 which impinge -upon the horizontal surface 153 first pavi through a circumferential,polarizer of the type shown in Figure 31. It comprises segmented radial portions 162 with the axis of polsriza.tion. 163 lying in the indicated planes. ro The axis of polarization of these segments coincide with the tangent of the circle whose center is the common vertical axi@ passingthrough the light source. By m eans of these radial segments of polarized sheets, hght passing downwardly 55 from light source 160 is -plane polarized to provide the properly polarized light,beam 155 as described above. Another means of polarizing rays which are directed upon horizontal surfaces is shown as a. 60 frustrum of a cone 65 which may be a completed cone as@shown b@ the dotted lines 166 or may terminate in a cut-off section 167 as shown in dotted lines. The cut-off section 167 may comprise an absorbing surface or an internal re65 fleeting surface of suitable characteristic or may be left open for the pas@age of non-polarized illumination as here shown. The frustrum of the cone 165 may be constructed of any suitable polarizer such as a plastic sheet polarizer con70 taining,properly aligned crystals. The axis of polarization of the frustrum of the cone is shown by dotted line 168 and said axis of polarization follows the eircumfekence of concentric circles ng a center in the @common Vertical axis of To effect the polarization of the light, I pro- 75 the cone. Ught then passing from the light
[10]2,402,176 19 8ource through this cone comprising the polarized sheet is properly polarized as shown at 158 for the light beam 156. It is understood that the frustrum of the cone or the comlz)leted cone shown may also be applied in lieu of the cir- 5 cumferential polarizer 162 to the lower horizontal surface. In other words, I provide the cone or cone frustrum shape having a polarizing axis as indicated, as an importaht, independent aspect of my invention to provide proper polarization for 10 light to be directed upon horizontal surfaces. Such a cone friistrum could also be utilized in lieu of the plastic polarizing disks shown in Figures 1 or 34 in connectign with lamps of the design there shown, or alone in connection with I r) ceiling lamps as shown in Mgure 27. For light which is to be simultaneously directed onto vertical surfaces such as picture I 50, I provide a cylinder which may comprise a sheet polarizer or segmented flat strips as shown in 20 Mgure 27. It is important that the axis of polarization be as indicated by the dotted lines i7C for illuminating vertical surfaces. In this case, the axis. of polarization of the polarizing cyliiider is such that these axes are all parallel 25 to the connnon vertical axis. The effect of this construction is to polarize horizontally-directed rays 15i in a vertical plane as showil at 152 and furthermor6 provide glare-free illumination for such vertical surfaces. These horizontally-di- 50 rected rays are such that they are substantially parallel to horizontal surfaces 153-154 and so cannot be reflected from these -horizontal surfaces to cause a glare. It is understood tha;t rays 151 are also directed udon vertical surfaces 35 at approximately 33, so as to provide the proper angle of incidence for best glare-free illumination. To effect this proper angular direction, it is best to provide block-outs or louvres and prevent t( a direct 900 angular impingement of the polarized light onto the vertical surface. Areas which are not illuminated because of these blockouts can be properly illuminated with glare-free polarized lamps suitably spaced apa@t which 45 are positioned to direct, at the proper angle, polarized light therefrom as shown in Figure 25. Mgure 15 is purely diagrammatic and is reduced to essentials, but it is understood that the principles embodied therein can be improved or en50 hanced by additions of suitable reflectors, diffusing mediurris and all other well known devices common in the art. In Mgure 16 I show a system for providing glare-free low intensity light j'or a room and its 55 contents which,, of,course, comprise both horizoixtal and vertical surfaces. To do this, I provide simultaneously horizontauy directed light rayi@@coritaining vertically plane polarized light and hght directed upon horizontal surfaces con- 60 taining light polarized in a plane normal to its Plane of incidence, both such famihes of rays being simultaneously projected. To carry out this system of illumination, I provide a hght source 175 which simultaneously projects light rays 176, 177 and 178 through polarizers 174 and 180. Polarizer 1'74 has an axis of polarization adapted to polarize light beam 176 so as to provide hght vibrating in a plane normal to the plane of final incidence of light as shown at 18 1. This 70 so-polarized light is directed onto a suitable reflecting surface i 82. Surface 182..has a suit@ible reflecting -surface such as a metauic reflecting surface. For example, 182 might be a. wala of suitable curvature 75. 20 covered with aluminum particles in a transpareni vehicle or the wall might comprise a metallic foii paper which might.contain embossed designs for the purpose of ornamentation. In the event that the general plane of the wall is de@ired to be siibstantially vertical, it is contemplated that the wall paper be suitably embossed or molded with directional metallic planes to cooperate with the aforementioned light source so as to direct a polarized beam upon horizontal surfaces at the angles indicated in this figure. SpecificaRy I mean by this that I may provide angular direct-, ing reflecting surfaces comprising a multiplicity of suitably oriented facets obtained by molding or embossing which, although collectively positioned in a substantially vertical plane, effectively act to direct light therefrom in the angular range which would ngrmally be 6btained by -a plane surface having the curvature indicated at 163. Referring now to the path of the light ray 176 after reflection from the reflecting surface 182, this polarized light is directed downwardly upon horizontal surfaces at the best angle to provide glare-free illumination. This range is, for example, from 20' to 70o with a preferred angle of approxiinately 331. Now referring to the rays intended for the illumination of vertical surfaces, specifically 177 and 178, 1 provide for the polarization of these rays by polarizer I 80 which polarizes said rays in a vertical plane as indicated at 183 and 186. Rays 177 and 178 are impinged upon the wall reflecting surface 183 which is of the character previously discussed and which is such that the particular curved section or embossed section cooperating yvith the directed rays 177 and 178 produce horizontally reflected'rays 187 and 188. In the drawing it is understood that rays 181, 188 and 189 are all traveling in horizontal directions; any appearance to the contrary being due to the perspective of the drawing. By horizontal directions is meant that the rays travel in a substantially horizontal direction, but of course there will be some deviation therefrom due to scattering and diffusing effect on the reflecting surface 183. A bottle 190 is shown as iuustrative of an object having vertical surfaces. It is to be pointed out further that vertical rays 187, 188 and 189 are preferably constrained by properly directing the reflecting surfaces or by blocking members so that said rays impinge upon said vertical surfaces at substantially the proper angle therewith. B3f the provision of a wall surface which imparts the indicated angular direction of the respective rays and which comprises a reflector that reflects polarized light, I provide not only for the aforementioned glare-free illumination of both vertical and horizontal surfaces, but I also Provide a low intensity soft illuinination within the room. Particularly I have provided a new system of illumination which comprises the dir I ectin . g simultaneously of a multiplicity of light rays, polarizing these in suitable Planes fGr the ultimate purpose of providing glare.@free iuumination for the Particular surfaces which the light ra:Vs gre to illuminate and for further carrying out this scheme I have provided metallized or other suit, able non-depolarizing reflecting surfaces of large area which, for example, may be the walls or ceiling of the room and as a further modifleation of this system I provide aii ornamentation of these surfaces, sueh omamentation being such as
[11]@,402,176 21 to fuuy absorb the light in certain areas or to reflect It without depolarlzation. It Is to be noted that the polarizing means 174 and 180 comprise two pblarizers having their axes of polarization at right angles and that these polarizers are respectively positioned so as to intercept and properly polarlze hght which after reflection from the cooperoting reflecting surface Is directed substantially onto particular planes. Figure 16 intended to be Illustrative of a broad new principle of great importance and utility and Is not limiting in any way, as many constmetions thereto of devices and methods well known in the art could be made, all without departing from the broad scope of this invention. Referring now more specifically to Figure 17, I show a polarizing unit 200 which comprises a multiplicity of plastic strips 201 separated by spaces 202. The strips are combined by applying a solvent to the edges thereof as at 203, which solvent effectively dissolves the surface of the strip at that point and causes an amalgamation and solid joining up of the respective strips. In lieu of a solvent, I may employ a thermo-adhesive or adhesive compounds generally but I liarticularly prefer to employ an adhesive means containing a solvent inasmuch as such solvent will have an effective sealing action on the edges of the composite to permanently seal the assembled strips against the entry of deleterious influences. It will be noted that the strips 201 are positioned with respect to each other in their composite form at a predetermined angle. This angle is such that the light beam 205 may be substantially normal to the plape 206 of the polarizing unit 200. A feature of this device is that the strips 201 may be Placed and permanently held in position at a larger angle with respect to the ray 205, because after emerging from the first strip, the ray is refracted at point 207 so that it assumes a greater angle of incidence upon striking the succeeding strip 208. As a consequence of this construction I may employ a fewer number of strips than would be required if the lessening of the angle of incidence did not occur as a result ofthe first refraction. That is, because the plastic strips are at a more acute angle with respect to the plane 206, fewer strips are necessary to provide the neces@ sary multiplicity of strips through which the light must ' pass to be properly polarized. Iu the fabrication of this article, it is desirable to employ as few strips as possible per unit area to provide effective polarization and the methgd I employ here is a device to minimize the niimber of these strips by Increasing the angle which these strips may make with the ray 205 without deviating from the proper critical value for best polarization of the beam directed normal to the surface 206. That is, the strips are laid out flatter in their assembly and hence 'extend :fa-rther along the extent of the unit which is in the direction along the edge 210. Another feature of this device is that the rays which during polarization are reflected as from 208, (ray 21 1), are reflected intemally between the respective sheets until substantially absorbed, asshown. The most important feature of this particular polarizing device is that the strips of preferably plastic material are so arrahged anguiarly with respect to each other and spaced tG provide a certain spacing between the respective sheets so that light such as 205 strlklng the unit substan@ 22 tiauy normal to Its surface 208 passes through preferably 25 separate plastic sheets and the spaces therebetween so that optiinum polarization is effected, these sheets being joined at their outermost edges Into a continuous surface which thereby forms the entire device into a permanent sealed substant ' tary unitary construction. Although I have set forth that the optimilm number of sheets is 25 through which the light must 10 pass, I have found that the effective range is substantial@y from 15 to 30. As further Blustrative of the construction of this device, refer to the reduced triangle 214 which is diagrammatically attached to unit 200. 15 The Me 215 which is the'base of the triangle Is parallel to the edge 210 and intercepts 25 sheets which are included between the hypotenuse 213 of the triangle and the base 215. Flne lines 217 represent the reduced strips 201. The angle 20 216 between the plane of the strips and the normal Incident ray 203 bears the following relation to the thickness of the strips and thid total thickness of the unit: nt 25 T= sin.-@216 Equation A where T is the total thickness of the unit, n Is the numi5er of sheets selected, which may be equal to 25, and t is the thickness of the sheets plus 30 the airspace adjacent thereto. As a further definition for the best construction of this device, <@ 216 is defined as follows: sin.@:21 @216=cos-'( Equation B 35 where A equals the index of refraction and --r2l9 is the critical angle of incidence of the light ray. striking the second plastic strip andsubsequent plastic strips, this angle being the optimum polarizing angle for the light. 40 It is further characterized by the followb3g: -,@219=tan-I Equation C where u is equal to the index of refraction of the plastic material which is uniform through-. 45 out. Combining B and C I obtain an equation which gives a definite angle 216 for any particular value of the material used, thus: sin (tan-'/A) 50 -,@216=cos-I Equation D IA Thus I provide a simple polarizing device comprising combined and slightly spaced preferably. plastic strips permanently positioned at the op55 tiinum polarizing angle with certain deflnite'relationships as above set forth with regard to the light to the thickness of the unit, which is determined by the angular position and the number of strips, namely about 25, which the light (;o 205 ig to traverse for optimum polarization thereof. For the best operability of this device, the spaces 202 between' the respective plastic sheets 201 should be small relative to the thickness of the plastic sheets In other words, if the plastic 65 sheets are in the order of .003, the spaces should be in the order of .0003 of an inch or -less. The polarization is effected, of course, in this unit, as ixx the various modifleations outlined above, by the respective abrupt changes in index of re70 fraction in the plastic strips and the airspaces therebetween. Although I term the spaces between the plastic strips airspaces, I include any medium that represents an abruptly different index of refraction of sufflcient magnitude, name75 ly .2 or more, and these spaces may be of my
[12]2,402 176 23 gas or liquid or solid niaterial having these requirements. This unit is characterized from a ' structural standpoint by the fact that it polarizes effectively light directed normally to its surface and also is 5 of such simple construction as to be readily available for many purposes. In lqgure 18 of the drawings, I have illustrated diagrammatically the manner in which light conventionally acts upon a surface of insulating 10 material. Let it be assumed, for example' that the reference character A constitutes the @@ject to be viewed and that this object is an insulating material, stich for exam le, as a transparent plate . p of glass 2" having an upper surface S and an I r) underlying wooden body 3". The object A may, however, constitute a body 3" which it is desired to observe and over which is positioned a transparent coating 2" 6r the part 3" may constitute a sheet of paper having printing thereon with a 20 glossflnishcorrespondingtothepart2". Ihave found that all insulating surfaces of whatever character possess these properties; the surfaces may be indeed of such diverse character as that of cloth or a rug, which ordinarily are nOt 2t, thought of as having a glossy finish. Nevertheless the principle herein explained for the comparatively simple case of say a glass plate over a grained wood surface extends to and Includes all-possible surfaces; except those of conductors 30 such as metals. There, is -always an improvement in the contrast of adjacent areas of differing -absorptive ability when the light component polarized normal to the viewed surface is eUminated according to this invention. 35 In any event, the mode of operation is the iame. In this figure, two vertical planes are shown. The surface S may, however, be other than horizontal in which,the planes 4" and 511, norr.ial thereto, will be other than vertical. The 0 vertical plane 4" is norinal to the upl*r plane surface of the part 2", while the plane 5" is nor mal to t]@e plane 4 " and normal to the upper plane surface of the part 2". The light source indicated at 6 is presumed to be substantially in the plane 4", while the observer or objective 7" is presumed to be in the same Plane. Ordinary light from any suitable source 6", illustrated as a candle, although it may be natural or artificial, either radiant or optically projected, passes frorril the source 6" to and impinges upon the surface 50 S at a point designated 8". Upon contact with this surface at 8" which we will assume to be a polished surface, the beam,is split into two parts, one part 9" is reflected directly from the surface 5, and through such reflection is substantially polarizbd in a vertical plane 4", as indicated by the lines 10" which denotes polarizgtion in a plane normal to the surface 2 ". The other part i I" is refracted at the surface of the part 2", passes downwardly through said part and iinpinges upon 60 the more or less light diffusive upper surface of the part' 3" at @L point indicated at 12". The diffusive character of the part 3" at tWs point reflects the thus refracted beam in an upward direction through the thickness of the part 2", (15. so that it merges from the upper surface of the latter in diverging rays constituting a beam 1311 diffused to the extent that it will not produce glare., The ray 911, however, substantiall3r plane To polarized in a vertical plane, may be referred to as the glare effecting portion of the transmitted beam and this impinges upon the eye 7" and causes the glare, making it impossible for the eye t(> properly analyze the characteristics of the 75 24 diffused beam 13". The foregoing is Illustrative of conventional obseirvation and coristitutes' no part of the present invention being here illustrated merely to form a basis by which the present invention may be more rea-dily understood. Beam 9" being surface-reflected is not affected by the absorptive Properties of the underlying layers of the surface such as 3". The intensity of 9" is therefore constant over the entire surface S. V-7hen the observer fotms an imag6 of the surface viewed, adjacent areas of that image are, more readily distinguished if the ratio of the larger intensity of one area to the lesser intensity of an adjacent area is great. The beam 91, always contribu es to reducing the ratio of intensity of adjacent areas of the observer's image of the object viewed. Thus, for example, If the absorptive ability of the underlyinglayers of adjacent areas of a surface be say, such that the 90 % of the light that is transmitted thereto (10 % being surface reflected) and one area diffusively reflects 20% of the light, and the adjacent area diffusively reflects 5% of the light; then if the surface reflected component is elirninated the contrast ratio is 20% 0 = 4 times whereas if the surface reflected component is not eliminated, the contrast ratio is 20+ 10 30 5+ 16 @1-5@ 2 times By reference now to Mgure 19, wherein similar parts have the same reference numerals, the source of light 6 " constitutes a source of ordinary light. It is adapted-to disperse its rays in the direction to impinge upon the surface S of the part 2" at the point B", as heretofore, but between the source 6" and the point S", is interposed a polarizing medium P, so constiiuted as to plane polarize the light from the source 61, in a plane normal to plane 4" and including the ray from the source 6",.as indicated by the lines 14", whereby the light passing through said polarizing medium and impinging upon the surface S at -8" is divested of the beam 9", shown in Mgure. 18, i. e., the vertical component of the transmitted beam, while the component 15" of such transmitted beam is iefracted at the surface S and passes downwardly through the part 2" to impinge upon the lower surface of the part 3"; or In general passes below the upper surface layer into the body of the material where it may be differentially absorbed and diffusively reflected by adjacent areas. It is thereupon reflected from said part 3" in a diffused manner' resulting in the diffused reflected beam 13", only, it be.ing, noted from Mgure 19 that the beam 1911, appearing In Figure 18, 1 and plane polarized in the verti . cal plane 4" is absent. The beam 13@' is of such character that it will not cause glare, but,wfil on the contrary provide clear contrast between adjacent portions of the part 3" and pprmit them t6 be effectually.seen by virtue of. ihid refl6cted diffused beam 13" to which I li@a',Ve ileferr,ed, for it will be observed that the@glare causing vertical component has been wholly eliniinated, while the remaining component bas been so modified as to render glare therefrom wholly absent or negligible. In the showing of -Mgures 18 and 19, I have referred to only one poilit 12", but, it is to be understood that the phenomena described is dupli-
[13]-.9,402,176 25 cated for other points in the upper surface of the part 311. It will, of course, be understood that the parallel lines indicating planes of polarization shown in Figures 18 and 19 are not Intended to Indicate complete polarization nor degree thereof, but merely show the predominatin planes of polar9 i7,ation. I have referred In connection with Flgure 19 to the employment of polarizing mediums more' specifleally designated by the reference character P. In practice, these polarizing mediums may partake of various forms and I, therefore, do not limit the present invention to any specifle construction, but will hereinafter describe several alternate polarized devices -*hich may be employed In this connection. However, ' for the purpose of illustration at this poiiit, it may be stated that I may use with high efficiency the polarizing medium fully disclosed in my application, Serial No. 662,090, fued March 22, 1933, which Issued into Patent No. 2,104,949, and directed to "Crystalline formation." Said application discloses among other things a polarizing medium comprising a transparent supporting member, such as a sheet of glass and on one surface of which s-neet is supported a crystalline layer havIng -the characteristic that when a light beam is passed through the glass and through the layer, the emergent beam will be polarized in a predetermined plane. This str@ucture is referred to here as well adapted for the purposes exhibited in -TIigure 19, wherein the said polarizing device may be positioned as Indicated at P in tMs figure. Tn the arrangement of Mgure 19, this polarizing device P may be mounted on or form part of a lamp casing or fixture. The objective 7 may be the eye of an observer, the lens of a camera or the like. In Mgures 20 to 32, I have shown practical examples. of the embodiment of Mgure 19 in commercial lighting flxtures, some of which' are adapted for direct lighting and some for.indirect lighting. Referring first to Mgure 20, wherein I have shown direct lighting, such as may be conveniently incorporated in a desk lamp, 1711 designates the lamp standard to which an appropriate lamp casing shown in the form of a reflector 18" is pivoted at 09". @n electric lamp 20" Is housed within the keflector and current is supplied thereto through wires in the usual manner. Across the open end of the reflector 18" Is a polarizi,ng medium P which may conveniently take the form which is shown in my copending application, above referred to, and I have shown mounted adjacent the polarizing medium and on the interior of the reflector a diffusing plate 2 1 " of ground glass or the like to break up the ima e .9 of the lamp illament prior to the passage of the beam through the polaxizing device P. The beani from the lamp-passes through the diffusing element 20 @' and then through the polarizing element P which serves to plane polarize the emergent rays 22" and 2211 in planes normal to a plane normal to A and including the rays 2211 as described in connection with Flgure 19. As such, rays 22" impinge upon the object A with the same results as described in connection with Flgure 19. Light polarized in the plane of polarization normal to the surface A is thus eliminated and the diffused component'results In the beam 13" being composed only of light differentially reflected by the contrasting areas of A. In Fig26 ally moved on the standard 171, into such optimum angle as to give the best results for reading or otherwise as may be desired. The structure of Figure 21 differs from the structure of Figure 20 merely in that a different forta of polarizing medium P is employed. Tn this instance, polarization is accomplished by passing the light beam through an appropriate Pile of transparent plates of glass or any other appro10 priate polarizing substance or substances so that the emergent beam 22" Is plarie polarized in a plane; a line In which, normal to the ray 22" is parallel to the surface viewed; the refiected polarized beam 22a" here being absorbed on an opti15 cally black surface as shown. The casing 98" shown in Figure 21 is, for a portion thereof adjacent the source of light, of parabolic confimation, so as to parallel the rays of light wwch pass through the polarizing ele20 ment P. Beyond this parabolic part of the reflector, the extended portion of the casing Is pref erably lined or coated with some absorbing medium, such, for example, as a flat black coating indicated at I Oa" to absorb those rays of light which 25 carmot efftelently be paralleled, as well as such rays as are reflected from the surface of the polarizing medium P. In this form of construction, moreover, an absorbing shield 18b" Is also preferably positioned forwardly of the source of light 3( to preclude the passage through the polarizing medium of the: direct divergent rays from the source of light and which could not be efficiently polarized. In the structures of Flgures 22 and 23, the 35 same standard Is employed as in the preceding structures, but the ca-sing 23" is of somewhat differentform. Ordinarylig htfromthelamp2C"is first passed through an appropriate optical system 26" which parallel the rays causing them to im10 pinge upon an appropriate set of plates P of transparent material or materials and the last plate o which Is preferably coated at its back surface with lanip black or the like. The plates are set at such angle that the beam 22" will be reflected in the 15 desired direction and the light of said beam'will be plane polarized in a plane, a line in which, normal to the ray 22 ", is parallel to the surface A. In Flgure 24, 1 have shown in perspective section a structure substent-tally the same as shown 50 in Mgure 20, but with the diffusing plate 2 1 " set -a further distanco away from the polarizing medium P. The reflector 18" employed in this connection is practically the same as shown in Flgure 20 and In these flgures, these reflectors are 55 preferably, though not essentially, parabolic. The reflector of E4gure 21 is essentially parabolic for the rays Impinging on plates must be parallel to be effectively polarized. In.Mgure 25, two sources of light of the char(10 aett!r show-n in Flgure 20 are employed being positioned in opposed relation to one -another, - so -as to collectively illuminate the object A which in this showing may be a picture, such as an oil painting or the like or a piece of tapestry, the lamp 65 casings 18" being tilted at the proper aiigle to. give maximum non-glare illumination and to Properly cooperate with one another. Reference has hereinbefore been made to a polarmng medium P used In conjunction with a sep70 arate diffusing medium 2 1 ". If desired, these two mediums. may be incorporated in a unitary construction Pd forming part of this invention and shown in Figure 26. In this flgure, a transparent plate 25", such as a plate of glass, is coated on ure 20, the casing 18" of the lamp maybe, pivot- 76 one side with a polarizing fHm P and at its oppo-
[14]27 site side, It Is provided with a diffusing surface 21". which may conveniently be produced by either einploying a diffusing coating or sand blasting surface of the plate 2 5 ". The said cotnposite construction may@ be used inconjunction witb any Practical arrangement employing the lnvehtion, as set forth in Figure 19, 1. e., any structure wherein the beam is adapted to pass through the diffusing and polarizing elements. Flgures 28 and 29 show another application of '@he Invention to direct lighting and more particularly in a wall flxture. Here two composite units Pd, as shown In Flgure 26, are mounted In an appropriate frame 26" before an appropriate source of light G" with the result that the beam which passes through the units Pd will be plane polarized In a plane normal to the vertical. A, room pr(perly lighted by a series of fixtures of the kind shown In these flgures will be devoid of glare on horizontal surfaces. Another adaptation of the Invention Is shown In Vqgure 27 In which flgure a i3lurality of strips each comprising composite units Pd are mounted in a circular frame 26" constituting a suitable support and wlthin the frame is positioned a source of light S" such as an electric lamp. All rays of light which pass through the units Pd will be plane polarized In a plane normal to the vertical plane. Iri the structure of Flgure 30, a somewhat different arrangement Is shown. The source of light S" Is mounted within the lamp casing 18" across the top of which Is positioned a polarizing plate or a composite plate, such as shown in Figure 26. The light Is thrown from the source of light directly and by reflection upwardly through the pola,rizing plate P and on to a conical diffuser 27", preferably of metal, positioned above the same. 7he Polarizing -medium used In the construction of Figure 30 is shown diagrammaticallv In Mgure 31 and must be of special construction. It is preferably built up of a plurality of segmental parts or sectiidns, each of wlilch is adapted to poiarize the planes normal to the radius, so that when these several sections are assembled, as shown, polarlzation.will take place substantially normal to all radii. That is to say, light passing through any portion of the polarizing medium will be properly polarized before impinging the reflector 27". The surface of the diffuser 27" if of metal will simply reflect the beam as Indicated. This surface may, however, be composed of metal flakes in transparent stispension with haphazard orientatiori, so as to reflect the light in all directions' Such a surface may be conveniently formed by using aluminum paint. , My observations show that metallic surfaces will not depolarize an incident Polarized beam so that everi though the surface of the part 2711 Is simply metallic surface, satisfactory reflection will result without glare, but I preferably use a diffusing surface of metal flakes to get a better distribution of the light. If the part 27" werenon-metallic, such as a flat white paint or calcined background, the polarized beam impinging thereon would be depolarized, but this might be overcome by covering said surface with metal flakes as stated. . The structure shown in Mgure 32 is a fixture embodying the combination of several of the arrangements hereinbefore referred to. Light from the source 6" passes through an optical system 28" to parallel the rays and thbnee Is passed through a polarizing PiIe P which Plane Polarizes the beam in a horizontal plane. The thus polar2,402,176 28 ized beam Is received upon th6 metallic or other non-depolarizing reflecting surface 29" and re-' flected upwardly against a diffusing surface 30" embodying the metal flakes in transparent suspension and with haphazarddrientation and from this surface the polarized light is reflected in diffused condition throughout the room, In which the fixture Is suspended. In order that the light may be dispensed from all sides of the fixture, 10 the optical system 2811 may be in the form of an annular lens coaxial with the source of light B" and the pile of plates which constitute the polarizing device me,* be in the fdrm of hollow truncated walls coaxially arranged and of the 15 same pitch. Similarly, the reflector 29" may be in the form of a frustum of a cone with the deflector 3011 similarly formed as will be understood by those skilled in the art. 31 " is an optically black absorbing surface for the discarded 20 polarizing component. The structure of Figure 33 is quite similar to the structure of Flgure 32, with the exception that the polarizing element P is in the form of a pile of pla with the outermost plate having 25 a light absorbing backing 31", such as a lamp black coating, such as to function in the manner described in connection with Flgure 23, the light being Po@arized during reflection instead of refraction as in Flgure 32. 30 The foregoing commercial embodiments of the invention are illustrative of a wide variety of apParatus which may be employed in practising the present invention. They all, however, operate on the generic principle that the light is Po35 larized prior to impingement upon the surface to be viewed. In certain of the apparatus.shdwings the object is viewed by direct illumination wEe in others the object is viewed by so-called indirect Illumination. In every case, however, the 40 glare producinig component of the light beam emanating from a common source of light is eliminated in such manner as to obtain a highly satlsfactory contrast between different portions of an object having greas of varying degrees of 45 light absorptive properties. As a resuit, the observer will see these different portions of the object In proper contrast without eyestrain or optical fatigue. In'direct lighting arrangements, such, for eic50 ample, as Illustrated in Figures 20 and 21, direct view of the source of light is sbielded by the casing 18", while the angle at which the-casing is tilted shields direct rays of polarized light from the line of sightdf the observer, so.that he views 55 the object A solely by reflei3ted light. The angle of adjustment of the casing is such in these cases as to give the best results. In the forms of the invention typified by the non-glare surface illumination, whose beam is included in the line 60 of sight of the observer, such, for example, as in Mure 27 Or 28, a diffusing screen should be used to give a large uniform field of lower intensity. In this connection, it is important to note that the polarmng plates referred to form a highly 65 practical way oi poiarizing light coming from' a diffusing screen, since they polarize well for rays having all angles of incidence. In practically carrying out this invention, I prefer, In all instances where the source of light is 70 within the lines of vision of the observer, to utilize in conjunction with the polarizing medium a diffusing screen in order to obtain a large field' of illumination of lower intensity. However, where the light is contained within a casing or 75 holder so constituted as to shield the source of
[15]29 light from the direct view of the observer, such a diffusli@g scre6n is not necessary although It maybe ustd If desired. Referring now more specifically to Mgure 34, T show a further for7n of Illumination means for providiiig.polarized light. This particular form of my invention is characterized by the fact that for the major reflecting surfaces I employ a plurality of surfaces belonging to the same family of parabolas. On a suitable base 230 which contains the light switch equipment 2134, is mounted a light source 232. The filament of this light source which I characterize by P is coincident with the comnion foci of all the ,parabolas wbich constitute the reflecting surfaces. Below and surrounding the light source 282 is the spherical reflector shield 233, the center of the sphere* of which Is also coincident with filament P. The sphere is substantially hemispherical with an opening in the bottom. The internal surface of the hemisphere 283 constitutes a reflecting surface which reflects light projected thereon back through the focal point F, to the walls of the rrajor reflectors of the lamp. This reflecting surface should be a true reflecting surface that is non-depolarizing, such p,s a bright chrome flnish or any mirror-like finish. ,. Another function of this reflector is to prevent any direct projection of light from tfie light source to the surface to be viewed which would cause Intense spotting and undesirable glare. It is one of the features of this lamp to provide in addition to polarized illumination, a large field of low intensity lighting. .'Me light from the fflament F that is upwe,rdly and outwardly projected both from the fllament itself or back from the internal reflecting surface of the shield through the filament F Is thrown upon the major reflectors 234 and 235. These major reflecting surfaces, as can be seen, belong to the same family of parabolas and constitute paraboloids of revolution about the common vertical axis passing through P. The common amis of parabolas 234 and 235 also passes thr(>ugh P and is characterized 1 by the angle 236 which is preferably equal to about thirty-three degrees, or in other words the angle for best polarization of the transmitted beam. The limit of the upper parabola of revolution Is determined by the ray 239 passing through the outermost pglnt on the diameter of the polarized disc 228 at an angle of 33'. It is to be noted that the hght source and the reflecting shield are sunk in a plane practically coincident with the plane of the polarwng disc 238. By means of this arrangement I provide a shallow con,struction for the lamp and hence a more effective lighting unit, and also make poqsible a new and novel result whereby I obtain a greater efficiency in the transmission of the polarized light by the method to be set forth herein. In other words, I reduce practically to the end point the -waste of any light beams within the, lamp enclosure. In the ordinary process of transmitting and polarizing light, it is well known that theoreticelly perfect transmission and polarization resu. I-s in only flfty per cent transmission of light. By means of the construction I set forth, I 6btain in lieu of the theoretical maximum of -fifty per cent light transmission and utflization, and the more practical forty per cent light transmission and utilization, a theoretical transmission of 100,7o, which is reduced, because of 2,402,178 30 practical Inefficiencies, to about 70%. 1 obtain this greatly increased quantitative transmission of polarized light from my construction because of the reflux action which I obtain and which I shall now describe. It is an important element of this reflux action that I employ as the reflecting surface, a depolarizing material which acts to depolarize, polarized light impinged thereon, thus changing polarized light to un10 polarized light. The depolarizing surface may lbei of a suitable wliite enamel such as a coating having a magnesium oxide base. White pigments are desirable if white light Is to be prodixced ancl if colored light is to be produced, 15 colored pigments may be employed. I do not use metallic surfaces for this reflecting surface because metallic surfaces are not depolarizing. I obtain maximum reflection ffom the surfaces of the major reflectors as well as complete de20 polarization of any of the light Impinged there on together with a certain amount, but not excessive, diffusion. For purposeg of illustrating the reflux action by means of which 11 obtain the hitherto unknown substantially quantitative 25 transmission of the polarized light, I shall trace the path of a light ray from the fflament IF. I show the ray travelling froni P to a on the surface of the reflector, whereupon it is reflected to point b on the polarizing disc 238. 30 The ray from a to b is not polarized as is shown by the spokelike marking 240. Mrhen the ray strikes the polarizing disc 238, the transnlitted part of the ray c is polarized in a plane normal to its Plane of lneidence as shown by the mark35 ings 24 1. The remaining part of the ray is reriected from b to d and is polarized In Its plane of incidence as Is shown by the parallel markings at 243. At d this ray is again reflected, and in being reflected, Is dep6larized by the re40 fleeting-surface at d. From d the reflected ray travels to the point e on the shield reflector 233, whereupon it i again reflected from the shield at point e to the surface cyf the reflector 235 which it strikes at f. At this point it is also unpolarized 45 light., From point f the reflected ray is directed @)pon the polarizing disc 238 at point g, whereupon a portion is transmitted through and becomes ray h which Is pi-operly polarized normal to Its plane of incidence as shown by the dotted 50 rnarkings 245. The remaining portion of the light i is reflected again toward the surface of the outer reflector 234 and is polarized in its plane of Incidence. The process of depolarization,, reflection and 55 projection upon the polarizing disc 238 follows again and again until practically no light is left. As a consequence of this construction, it now becomes possible to project polarized light from a lamp without excessive loss by internal reflec60 tion and absorption of the reflected polarized light. By this construction I obtain a theoretical uttlization of the light from the light source of 100%. I have found that as a p(ractical matter I obtain about 70% of the light. As I 65 liave stated before, this is approxtmately 100% im@rovement over the effective light obtained in prior polarizationdevices. Returning now to the construction of the reflecting surfaces, these may be conveniently 70 constructed as follows: Through P draw the common axis of the parabola at an angle 236 ea.ual to approximately thirtythree. degrees. This common aXI's of the parabola is 246. From F mark off on 246 a distance equal to ihe radius 75 of the maximum diameter of the polarwng disc.
[16]2,402,176 31 Tlds is defined @by the distance from P to the lowerinost point on the reflector 234. Plrom t-his center of. curvature 247 draw a radius starting at the outermost -point of the polarizing disc and continue up to any arbitrary point 248 which marks the beginning of the next parabola. In constructing the next parabola 235 the diameter 245 of the lowermost part of this next uppermost parabola, 235 Is decided upon. A new point is marked off on line 246, such, that the distance from the new center Gf curvature 250 of the line 246 to the focal point P is the sa@ne as the distance to the point 249 which represenu the continuation of the new parabola. The limit of the upper parabola at 256 Is deilned by the ray 239 which travels at the desired optimum angle for best polarization of the light and - which intercepts the outermost part of the diameter of the polarizing plates 238. The up-per parabola may be terminated at the point 246 resulting In a cutaway portion at the top.of the lamp for Indirect light, or this top portion of the lamp shown in dotted lines may comi@rise a spherical reflector 257 which reflects light downwardly. This reflector 257 does not,belong to the family of parabolas 234 and 235. 1 The specific construction features of the polarizing mean@ .238 comprise a multipliefty, preferably from IS to 30, of plastic sheets, sealed at the outer edges 260 and the Inner edges 261 and held at these points by outer clamp 262 and Inner. clamp 263. Concentric supporting rings 265, 266, 267 and 268 render such support to the laminated composite superimposed plastic sheets as to prevent sagglng or displacement. These concentric irings are suitably supported by radiallyextendingarms270and271. Asshown, the concentric rings may be inset in the radial arms. It is Important to note, of course, that the total area occupied by the supporting radial arms and concentric rings is relatively so small that It does not interfere with the light transmitted through the polarizing unit. Because I consider this presently described lamp to be an extremely important part of my invention, I wish to summarize the principm factors In connection with the construction and physir,al operation thereof. 1. The major reflecting surfares of the lamp belong to the same family of parabolas. 2. 7he axes of the parabolas,coincide with the direct angle of incidence for optimum polarization, namely about thirty-three degrees. 3. The: end point of the uppermost parabola is deflned by the light ray directed therefrom which strikes the polarizing means at approximately an angle of thirty-three degrees at the outermost point of the polarizing means. 4. The radius of ourvature of the parabolic reflector Is substantially equal to twice the distance between IF, the, light source, and the reflecti g surface and the center of curvgture lies on the reflected ray through the focal point. 5. A ' multiplicity of parabolas may be employed to provide for a shallow lamp bowl and for more efficient lighting. 6. The shallower bowlprovides more efficient lighting because there is reduced to a minimum light which is directed against other than the polarizing means and because there is less diffusion or spreading of the light. 7. The lowering of the spreading due to diffusion Is important because I desire to employ a depolarizing internal reflecting surfa,'ce for 32 the major reflectors and such depolarizing reflecting surface has a tendency to diffuse the light. By reducing the path of travel of the. light, I reduce the spreading of the light or 6 diffiision. 8. I employ a clear glass bulb as the light source so that light.from tht, reflecting shield is projected for utilization on the walls of the majidr reflectors. 10 9. My light source is in substantially the same plane as the polarizing means for greater utiuzation of the light and more efficient reflection. 10. By employing depolarizing intemal surfaces I obtain a reflux action that produces an 15 entirely different measure of increased light transmission of suitably polarized glarefree light. A further important element of my invention lies in thepolarizing disc itself. This polarizing disc Is shown In plan view in Flgure 35. It is 20 shown in cross-section in Fligure 34. As can be seen it comprises a multiplicity of superimposed discs of transparent moterial. Because of the possibility of easy compositing, and because it can be formed into very thin sheets, I prefer to use 25 a plastic material, as described above. VVhen using such plastic material, I can combine and suitably hold the desired number of very thin plastic sheets preferably about 15 to 30 in niimber, and preferably .0015 inch thick or less, 30 although the thickness may be of a maximum.004 inch. The multiplicity of thin plastic sheets are held together and about the periphety 290 I apply solvent which may either be a low boiling point solvent such as acetone or alcohol, or a high boil35 ing point solvent, such as dibutyl phthalate or methyl "Cellosolve.11 The suitable solvent Is applied not only to.the external periphery 290 but also to the intemal periphery 291 and I may further apply pressure to these edges to obtain suit40 abl@ flow of the respective plastic sheets to get firm adhesion and preferably a iinitary mass at these points. The pressure may be applied between rolis, and if necessary, heat may be furthbr applied to facilitate the softening and amalgama45 tion of the respective axeas at this point ' By obtaining a flow of the plastic material in these parts, the light unit is completely and permanently sealed against entrance of deleterious influences. The polarizing unit is f@rther so 50 sealed so that the respective minimum spacings between the Plastic sheets Is maintained and separation Is prevented because of the low ptesgure within the uiiit that would result, the pressure of atmosphere thus permanently maintain55 ing the layers In close relationship. A further important result of this fotmation of external and internal plastic rings integral with the polarizing disc is the rigidity which such construction has. By causing a flow at the inter60 nal and extemal periphpry of the disc, 1, in effect, provide two supporting rings for the unit at these points. The shape of the unit is, of course, not to be restricted to annuiar, but may vary according to 65 the shape of,the device in which the polarizing unit is to be employed. The edge seal can be effected for any desired shape and in the event that there is no internal opening, the sealing of the external periphery results in a decidedly Im70 proved polarizing unit. Another means -of carrying out the above invention is shown in Figure 36, wherein plastic layers 313 are shown on each side of the planular central polarizing layers 307. Incorporated in plas75 tic layers 313 are suitable prismatic inclusions or
[17]2,402,176 33 open spaces 1 4. As shown, the triangular prisms are forzned by extruded openings as the plastic mass travels through a die containing cores of the section shown and of the predetermined spacings shown. Ray 300' entering 313 is bent by succes- r, sive refractions within the plastic mass at the predetermined angularly positioned surfaces formed by the prismatic inclusions.or openings as shown, such that the ray, upon emergence from the first layer 313, assumes an optimum angle for 10 pola,rization In travelling -through the polarizing layers 307'. Upon emergence from 307', a second layer 313, similar to the flrst layer 313 and suitably positioned with reference to the emerging ray, acts upon the emerging ray to bend it into 15 par@llelism with the Initial ray 300'. In the:ftrst method, speciflcally I provide mean,s for reflecting and depolarizing or first depolarlzing and then reflecting the reflected component from the polarizing medium.. The reflected com20 ponent is that component which is Polarized in the plane or incid6nee in contradistinction to the transmitted beam which is polarized in a plane normal to the plane of incidence. I further propose that the above redirecting 25 means be made unitary or integral with the polarWng structure above described. This may take the form of embossings of the respective layers or embossing of the outer supports of these layers, or It may be effected by treatment of the respec30 tive layers of the device, preferably of the lower side of each upper layer. Another embodiment of my invention lies in the use of the composite polarizing unit of this Invention in connection with Venetian blinds. 33 By Interlacing the composite polarizer between the respective strips of the Venetian blind, I effect first a positioning of the polarizing composite with respect to the light impinged thereon to effect proper polarization of such light, and, 411 by adjusting the angle of the strips, as can readily be done in the standard type of Venetian blind now aiailable, it is possible to adjust the angle of impingement for the oncoming rays of daylight which vary from time to time during 45 the day to always get the optimum effective polarization. Of course, if the conventional polarizer were used In connection with Venetian blinds such as one containing aligned particles of polarizing crystals in a plastic sheet, it would not be 50 necessary to adjust the angle of the strip to obtain maximum polarization. As another emb(>diment of my Invention I proPose the interlacing or weaving of composite strips containing twelve or more thin transpar55 ent plastic layers Into a fabric which is capable of polarizing .1i@ht transmitted therethrougb when the impinged light Is at a polarizing angle to the plan6 of the fabric. I further provide as a polarizing unit a comao posite which is A modification of that shown in Figure 36. Instead of employing the prisms 314 shown there, I propose to employ substantially parallel glass rods or gla8s fibres or other elongated light refracting or light scattering bodies. 65 The function of the above mentioiied light refracting or light scattering bodies Is to bend the incident hght into a multiplicity of directions In one plane only; this plane being normal to the 34 These refracting bodies may be Incorporated within the transparent plastic material having a different Index of refraction than the light refracting bodies. A light ray striking such a layer will be scattered into a multiplicity of directions and upon emerging from this layer and then passing through the polarizing layers, those emerging rays which are within the polarizing angular range wi]I be polarized, whereas those rays which pass almost normally Incident to the polarizing layers (outside the proper polarizing range) will remain relativeiy non-oolarized. All these rays upon emerging from the polarizing layers again strike another light scattering layer similar to that above described and are again scattered In the same plane as above described. The rays which pass through the firstpolarizing layer almost normally Incident thereto and consequently are still unpolarized, will be scattered again by the second scattering layer and most of these rays will pass through subsequent polarizing layers at the proper angle to effect their polarization. The rays which were previously polarized will iemain so or become even morecompletely poiarized upon their transmission through the second polarizing layer. In general I propose poiarizing the light by scattering in one plane, polarizing the scattered ray.@, again scattering and poiarizing again,- alternately, so that all nonpolarized rays . are eventually -exhausted as they mugt assume, after at least one of the said scattering operations, the proper angular direction with reference to the polarizing layers so as to become polarized. My polarizing unit, therefore, comprises spaced parallel layers containing light scattering materials between which are placed sufflcient layers of thin isotropic plastic to effect the polarization of light passing from these light scattering bodies. Succ6ssive layers of light scattering bodies and composite polarizing layers are empl6yed alternately. For example I can use a light scattering layer followed by seven thin polarizing layers, followed by another light scattering layer, followed, in turn, by seven more thin polarizing layers; this being repeated until there are, for example, four light scattering layers with four composite polarizing layerscomprising seven layers each of thin plastic material placed alternately between the light scattering layers. In United States application iqo. 755,557 of which this is in pe@rt a continuation, I refer to the polarization effect obtained by passing the light beam through an appropriate pile of plates of glass or any other appropriate polarizing substance or substances. In the present application, I specifically describe means for efficiently ai@id commer . cially producing polarization effects using such appropriate piles of plates of these above mentioned substances other than glass because glass is not presently obtainable in suitably thin non fragile sheet form because of other deftciencies in essential characteristics. The polarization unit of my invention comprises mu Itiple she6ts of thin transparent ma-, terial of the following characteristics, direction of elongation of the light refracting To Thickriess: Maximum thickness-about .004 inch; or, light scattering bodi@@s. This may weU be preferred range-.0015 inch or less; desired effected by theuse of a plurality of glass threads thickness-,about .00088 inch. lying side by side in a plane substantially parallel to the polarizing layers or a multiplicity of lay- Number of sheets: Rafige-15 to 30; desired numers of. such glass threads could be employed. I& ber-about 25.
[18]2,402,176 35 Composition of sheets: Isotropic transparent plastic having surfaces which do not ordinarily adhere to one another. Surfaces should be quite plane and have a minimum of irregularities. 5 Distance between sheets: GTeater than the wave length of light since If a smaller space is employed, interference phenomena may take place which appear to affect polarization. The 10 ma)dmum spacing is about .010 Inches. More than that causes unsetting and consequent distortion in the polarization and transmission of the light. When solid sheets separated by air or gas spaces are employed, the spacing 15 desirable Is equal to a few wave lengths of light. Spacing can be effected: 1. Suitable spacing means tuch as spot adhesive or preformed spaces which may be adhesive at intervals between the faces of adjacent sheets. 2. Air or 20 gas included and sealed between adjacent sheets. -3. Spacing at the edges and transverse tension on the entire assembly. Assembly of composite polarizing unit can take 25 place under mechanical or slightly reduced air pressure duiing which time it Is sealed. 7ben atmospheric pressure holds the sheets together. I When the composite Is formed continuously as shown In, Flgure 7 or when composites of large 50 area are made, adapted to be cut to small size for fabrication, the air spacing cells are preferably of small lateral extent so as to prevent extended separation. the plastic sheet composite is to allow for relative freedom of motion between the respective layers and the support elements In a lateral direction while at the same time maintaining the planular 45 position by means of the supporting elements. TWs may be effected by a flexible coupling or Joint 13-6tween the respective layers, which also may act as a seal, such as rubber taped edges. One of the problems connected with the uti- 50 lization of multi layers of thin plastic sheets which are hermetically sealed against deleterious Influences is the expansion of the gas contained in the spaces between the layers with a consequent tendency for the layers to bulge or wrinkle. The r,5 expansion is usually caused by heat as from the light source with which the unit is being used. However, when the composite is formed under slightly reduced pressure, the gas In the spaces is initially at sub atmospheric pressure so that 60 subsequent heating during utilization as in a lighting fixture will not expand the gas to such a point -as would cause it to bulge or wrinkle the plastic layers. The heat to which the composite polarizing (15 unit is'necessarily subjected when used in a light 1 flxture with a filament light source may be reduced by employing a dark exterior - coating which radlates heat on the exterior enclosure of the light source. This enclosure may be the re- 70 flector. A maximum practical area enclosure should be employed to afford adequate radiation of heat. To protect the cOmPosite plastic against heat - effects, I further propose to coat the Interior of To 36 the reflecting surfaces with a hetlt absorbing material such as glass or plastic containing dissolved iron salts or any of the well known at absorbing materials. 7bis may take the form of a clear glass enamel containing heat absorbing material superimposed over the d6polarizing reflecting surface. Alternatively, the heat absorbing material could be employed as the uppermost layer of the coniposite polarizer. For effecting the rapid manufacture of the polarizing unit which operates on the principle of abrupt changes In index of refraction shown in Figures 5 and 6, I may extrude the plastic through a die which contains suitably positioned cores which cores form the spaces 12 shown in Flgure 5. To maintain the spacing -of the plastic at these points I may employ hollow core parts in the die through which I supply gas or liquid under pressure to these spaces. When I employ a thermoplastic, I prefer to use a relatively cold gas or liquid to chill and rapidly set the walls of these spaces. If the material is such as hardens under the influence of suitable chemical agents such as acids, alkalis, etc., then I sup@ly such setting agents through the above mentioned hollow cores. I may remove such setting agents if they have deleterious results by flushing with a HqWd or gas. A still further method of manufacturing comprises extruding layers of plastic and providing the necessary spaces therebetween by shaping the extrudirig sheets so that they have formed integrally therewith, surface projections at suitable intervals to effect the proper spacing of the in Figure 6 and combining there layers if necessary between pressure rolls. 'Mus from a single extrusion die, 11 form a complete polarizing device from Isotropic plastic or plastles. The light directing polarwng unit shown In Mgures 36 and 37 may be formed by simultaneous extrusion of the respective component parts as described above. The extrusion the is so shaped as to form upper and/or lower layers with suitably shaped surfaces so as to give the. prism action that is essential for properly directing the light to the centrauy positioned composite layers at a P(>Iariztng angle. The light directing effect can further be obtained in the extrusion operation above described by including prism bodies, properly oriented, in the upper and lower iayers of the composite or by forming prism shaped openings cc)ntjnuously with the upper and lower plastic layers. The manufacturing of the polarizing device shown in Flgure'17 may be effected by compositIng plastic strips as discussed hereinbefore or the unitrnay be more rapidly nianufactured by extrusion. 7-ne die opening employed for this extrusion should contain suitably positioned parallel cores for effecting the spacing of the strips. To maintain the spacing between the strips against collapse the cores may be hollow and a gas or liquid imder pressure may be forced into these spaces to maintain the separation of the plastic strips during solidifleation. In this method the forward end of the extruded plastic is closed to hold the gas under pressure contained therein. Altematively the separation may be effected by A support for the COMPosite unit may be formed 35 sheets. rm6 extruded sheets are prefera-bly joined to totally encase the unit as by dipping the formed before setting so that adhesion between the recomposite layers In a suitable hardenable trans- spective sheets Is readily obtained without addiparent material which upon hardening renders tional adhesives. surface support and effectively seals the edges of Alternatively, I may si'multaneously extrude a the unit. 40 multiplicity of layers, said layers having alter. One way of ellminating the buckmg effect in natively different indexes of refraction as shown
