JP2006518486A - Polarization recovery system using redirection - Google Patents

Abstract

The polarization recovery system includes a polarization beam splitter that transmits useful polarized light in an output direction and reflects non-useful polarized light in a first orthogonal direction substantially orthogonal to the output direction. An initial reflector can reflect the non-useful polarized light in a second orthogonal direction that is substantially orthogonal to the output direction and the first orthogonal direction, and the final reflector causes the non-use polarization light to be reflected in the second orthogonal direction. It can be reflected in the output direction. The non-useful polarized light can be substantially rotated to useful polarization light by the initial reflector and the final reflector.

Description

  This application is a provisional application, the disclosure of which is incorporated herein by reference, 60 / 448,471 filed on February 21, 2003, and 60 / 469,393 filed on May 12, 2003. And claim priority. This application is currently US Pat. No. 6,587,269, filed on Jan. 21, 2003, which is a continuation of application No. 09 / 814,970 filed Mar. 23, 2001. This is a continuation-in-part of copending application No. 10 / 347,522.

  The present invention relates to light recovery not used in other situations in a projection system.

  The floodlight display displays a work by projecting light onto a screen. The light is arranged in a pattern of color or brightness and darkness, or both. These patterns are seen by viewers who make these patterns their own by associating them with images such as characters and faces that they are already familiar with. The pattern can be formed by various methods. One way to form the pattern is by modulating the light beam with a stream of information.

  Polarized light can be modulated by filtering it with a polarizing filter. Polarizing filters generally pass light when their polarization matches the polarization of the incident light. Liquid Crystal Display (LCD) By using an imager, modulation can be performed on an LCD projection display. The LCD imager has pixels that are modulated by changing to a polarization that matches or differs from the polarization of the incident light. This light input to the LCD imager changes the polarization of the selected pixel when the LCD pixel is modulated, and the selected pixel becomes dark when the light output from the imager is analyzed by another polarizing element. Polarization is performed so that The pattern can be projected on the screen as the presence or absence of light. If the pixel polarization is modulated by the information in a pattern that is well known to the viewer, the viewer can recognize the pattern projected on the screen.

  One method of polarizing light for an LCD imager is by a polarizing beam splitter (PBS). Polarized light can be provided to the imaging system by an array of lenses, such as compound eye lenses, and an array of polarizing beam splitters. A radial reflector can be used with a compound eye lens to focus the light so that it is approximately parallel. The beam is split into many parts by a lens array, and each part is refocused to the polarizing beam splitter array by a separate lens array. However, the brightness of a light source such as an arc may be reduced by a parabolic reflector. Furthermore, the efficiency of the compound eye lens recovery system is highly dependent on the alignment of the two lens arrays and the polarizing beam splitter array. Finally, a polarization recovery system consisting of a parabolic reflector and a compound eye lens may not be suitable for a continuous color single imaging system.

  A continuous color can also be created by using an elliptical reflector with a light pipe and a color wheel. However, such systems still require a polarization recovery system and do not solve the inherent brightness loss associated with elliptical reflectors. The light output from the polarizing beam splitter array is then linearly polarized and focused on the target. Each polarization beam splitter splits unpolarized light into a plurality of beams having different polarizations. After the light is polarized, only one of these beams will be the correct polarized beam for input to the LCD imager. The other beams are of incorrect polarization and therefore cannot be used as they are.

  Unpolarized light can be recovered by converting it into useful light of the correct polarization using a polarization recovery system. Various methods have been developed to convert non-right polarized light into correctly polarized light so that it can also be used. One method transmits the first polarized light 102 from the polarizing beam splitter 104 directly to the output 106, as shown in FIG. 1, while the second polarized light 108 is transmitted at an angle, for example 90 degrees. This is a method of reflecting the output 106 at an angle such as. At this time, the second polarized light 108 is reflected so as to be directed to the output 106 in parallel with the first polarized light 102. In the optical path of the second polarized light 108, a quarter wave or half wave plate is used to rotate the second polarized light 108 to the first polarized light 102 so that the output is composed only of the first polarized light 102. A delay plate 110 such as is disposed.

  The retarder plate rotates light from one polarization to another by slowing the light in one plane while allowing the light to pass relatively unimpeded in the opposite plane. The speed at which light propagates through the medium is generally related to its wavelength. Therefore, the degree to which light is decelerated is also related to its wavelength. A delay plate applied to broadband light must pass light of various wavelengths, so some of the light will be more delayed than the other parts. The delay plate is typically tuned for a specific wavelength. In particular, wavelengths longer or shorter than the tuned wavelength are not completely rotated from unavailable polarization to the correct polarization. Thus, some of the light with wavelengths longer or shorter than the tuned wavelength is lost or at least not recovered. In addition, the delay plate is relatively expensive and often unreliable. The delay plate makes the polarization recovery system itself expensive and unreliable.

  Although these systems are used commercially, the cost of their components is high, and they require precise alignment and optical design. Accordingly, there is a need for a system that performs polarization conversion with high efficiency, has a simple structure, and is low in cost.

  According to the first aspect of the present invention, the polarization recovery system transmits polarized light that is useful in the output direction and reflects non-useful polarized light in a first orthogonal direction that is substantially orthogonal to the output direction. A beam splitter is disposed so as to be capable of reflecting with respect to the first orthogonal direction, and the non-useful polarized light is substantially orthogonal to the output direction and the first orthogonal direction. An initial reflector that reflects and a final reflector that is disposed so as to be able to reflect in the second orthogonal direction and reflects the non-useful polarized light in the output direction; The reflector and the final reflector are configured to be substantially rotated to the useful polarized light.

  In the second aspect of the present invention, the polarization recovery method includes a step of polarizing light into substantially useful polarized light and non-useful polarized light, a step of transmitting the useful polarization light in an output direction, and the non-useful polarization. Reflecting light in a first orthogonal direction substantially orthogonal to the output direction; and second orthogonally orthogonally intersecting the non-useful polarized light with respect to the output direction and the first orthogonal direction. Reflecting in the direction and reflecting the non-useful polarized light in the output direction.

  In a third aspect of the invention, the polarization recovery system comprises means for polarizing light into substantially useful and non-useful polarized light, means for transmitting the useful polarization light in the output direction, Means for reflecting the non-useful polarized light in a first orthogonal direction substantially orthogonal to the output direction; and the non-useful polarized light substantially in the output direction and the first orthogonal direction. Means for reflecting in a second orthogonal direction orthogonal to and means for reflecting the non-useful polarized light in the output direction.

  FIG. 1 illustrates a polarization recovery system, FIG. 2 illustrates a schematic diagram of a polarization recovery system according to an embodiment of the present invention, FIG. 3 illustrates a polarization recovery device used in an embodiment of the present invention, and FIG. FIG. 5 illustrates a polarization recovery device used in an embodiment of the invention, FIG. 5 illustrates a polarization recovery device used in an embodiment of the present invention, and FIG. 6 illustrates linear and taper used in the embodiment of the present invention. FIG. 7 illustrates various cross sections of the light pipe used in the embodiment of the present invention, and FIG. 8 illustrates various structures of the light pipe used in the embodiment of the present invention. FIG. 9 shows a polarization recovery device used in the embodiment of the present invention.

  It is desirable to recover and make available polarized light available by converting it to the correct or useful polarization. Since the retardation plate makes the polarization recovery system more expensive and less reliable, it is desirable that the polarization recovery be performed without the use of a retardation plate. It is also desirable that polarization recovery be performed on broadband radiation. It is desirable that the polarization recovery system be relatively simple to manufacture and assemble. Furthermore, it is desirable that the polarization recovery system allows the use of a color wheel in a single imager system.

  FIG. 2 illustrates a polarization recovery system 200 according to a first embodiment of the present invention. The polarization recovery system 200 can include a polarizing beam splitter 202, such as a multilayer coating or a wire grating polarizing beam splitter. In one embodiment, the light input to the polarizing beam splitter 202 can come directly or indirectly from electromagnetic radiation, ie a light source 212. In one embodiment, the source 212 of electromagnetic radiation can be an arc lamp such as a xenon lamp, a metal halide lamp, a high intensity emission (HID) lamp, or a mercury lamp. In alternative embodiments, the source 212 can be a halogen lamp or a filament lamp.

  In one embodiment, the polarization recovery system 200 can include an input light pipe 224, a supercube 268, and an output light pipe 232, as illustrated in FIGS. In some embodiments, the output light pipe 232 can be a homogenizer or an integrator. The output of the input light pipe 224 can be connected to the prism configuration, ie, the supercube 268. The input light pipe 224 can use Total Internal Reflection (TIR) to propagate light to the supercube 268.

  In some embodiments, the input light pipe 224, the output light pipe 232, or both of these input and output light pipes 224, 232 are progressively tapered light pipes as illustrated in FIG. 6A. Or a progressively decreasing tapered light pipe as illustrated in FIG. 6B, or a linear light pipe as illustrated in FIG. 6C. In some embodiments, the input light pipe 224, the output light pipe 232, or both of these input and output light pipes 224, 232 are rectangular, circular, as illustrated in FIGS. 7A-7H. It can be triangular, rhombus, trapezoid, pentagon, hexagon, or octagon. In some embodiments, the input light pipe 224, the output light pipe 232, or both of these input and output light pipes 224, 232 may be fiber optic, optical, as illustrated in FIGS. 8A-8E. It can be a fiber bundle, a fused fiber bundle, a polygonal waveguide, or a hollow light pipe.

  Several embodiments of the polarization recovery system 200 are illustrated in FIGS. Polarizing beam splitter 202 is illustrated in FIGS. 3B and 4B with unpolarized light from input light pipe 224 and usefully polarized light 204 with polarization 270, as illustrated in FIGS. 3A and 4A. Thus, the light 208 can be separated into the non-useful polarized light 208 having the polarization 272. The polarizing beam splitter 202 can transmit useful polarized light 204 in the output direction 206 and reflect non-useful light 208 in a first orthogonal direction 210 that is substantially orthogonal to the output direction 206. In one example, polarization 270 can be substantially p-polarized or horizontally polarized light, while polarization 272 can be substantially s-polarized or vertically polarized light. In another embodiment, the plane of polarization can be reversed.

  The useful polarized light 204 propagates through the polarizing beam splitter 202 and is redirected by the first output reflector 220 and the second output reflector 222 as shown in FIGS. 3A and 4A, and the polarization 270 is not changed. The second output reflector 222 can be left as is. On the other hand, the non-useful polarized light 208 can be reflected by the initial reflector 214 after exiting the polarizing beam splitter 202, as illustrated in FIGS. 3B and 4B. The initial reflector 214 can reflect the non-useful polarized light 208 around an axis substantially perpendicular to the plane of polarization 272 of the non-use polarization light 208, which in this case is the s or vertical plane. The final reflector 218 can then reflect the non-useful polarized light 208 in a direction parallel to the output direction 206. Accordingly, the inclined surface of the initial reflector 214 can be rotated 90 degrees with respect to the final reflector 218. Non-useful polarized light 208 is still referred to as non-useful polarized light 208 for tracking purposes, but the plane of this non-useful polarized light 208 is now horizontal or substantially coincident with that of useful polarization light 204. Since it is in the p-polarized state, it is already useful polarized light. In one embodiment, both useful polarized light 204 and non-useful polarized light 208 are connected to output light pipe 232 and are homogenized.

  In one embodiment, the first output reflector 220 can be arranged to be reflective with respect to the output direction 206. This first output reflector 220 can reflect useful polarized light 204 in the second orthogonal direction 216. In some embodiments, the first output reflector 220 can be a mismatched impedance such as a prism, a right angle prism, or a mirror. In one example, the first output reflector 220 can include a coating that transmits a predetermined portion of the electromagnetic radiation spectrum. This may be used to remove unavailable invisible light before it is captured in the imager. In some embodiments, the predetermined portion of the electromagnetic radiation spectrum can be infrared light, visible light, a predetermined band portion of the wavelength of light, a specific color of light, or a combination thereof. In another embodiment, the coating can reflect infrared light, visible light, a predetermined band portion of the wavelength of light, a specific color of light, or a combination thereof.

  In one embodiment illustrated in FIG. 3A, the second output reflector 222 can be arranged to be reflective with respect to the second orthogonal direction 216. The second output reflector 222 can reflect the useful polarized light 204 in the output direction 206. In another embodiment illustrated in FIG. 4B, this second output reflector 222 can be arranged to be reflective with respect to the output direction 206. The second output reflector 222 can reflect the non-useful polarized light 208 in the second orthogonal direction 216. In some embodiments, the second output reflector 222 can be a mismatch impedance such as a prism, a right angle prism, or a mirror. In one example, the second output reflector 222 can include a coating that transmits a predetermined portion of the electromagnetic radiation spectrum. This may be used to remove unavailable invisible light before it is captured in the imager. In some embodiments, the predetermined portion of the electromagnetic radiation spectrum can be infrared light, visible light, a predetermined band portion of the wavelength of light, a specific color of light, or a combination thereof. In another embodiment, the coating can reflect infrared light, visible light, a predetermined band portion of the wavelength of light, a specific color of light, or a combination thereof.

  In one embodiment, the initial reflector 214 can be arranged to be reflective with respect to the first orthogonal direction 210. The initial reflector 214 can reflect the non-useful polarized light 208 in a second orthogonal direction 216 that is substantially orthogonal to the output direction 206 and the first orthogonal direction 210. In some embodiments, the initial reflector 214 can be a mismatch impedance such as a prism, a right angle prism, or a mirror. The mismatch impedance can reflect waves such as electromagnetic waves like echoes. The mismatch impedance can, for example, reflect a part of the wave or a certain wavelength range, and at this time pass another part of the wave or another wavelength range.

  In one example, the initial reflector 214 can include a coating that transmits a predetermined portion of the electromagnetic radiation spectrum. This may be used to remove unavailable invisible light before it is captured in the imager. In some embodiments, the predetermined portion of the electromagnetic radiation spectrum can be infrared light, visible light, a predetermined band portion of the wavelength of light, a specific color of light, or a combination thereof. In another embodiment, the coating can reflect infrared light, visible light, a predetermined band portion of the wavelength of light, a specific color of light, or a combination thereof.

  In one embodiment, the final reflector 218 can be arranged to be reflective with respect to the second orthogonal direction 216. The final reflector 218 can reflect non-useful polarized light 208 in the output direction 206. In some embodiments, the final reflector 218 can be a mismatch impedance such as a prism, a right angle prism, or a mirror. In one example, the final reflector 218 can include a coating that transmits a predetermined portion of the electromagnetic radiation spectrum. This may be used to remove unavailable invisible light before it is captured in the imager. In some embodiments, the predetermined portion of the electromagnetic radiation spectrum can be infrared light, visible light, a predetermined band portion of the wavelength of light, a specific color of light, or a combination thereof. In another embodiment, the coating can reflect infrared light, visible light, a predetermined band portion of the wavelength of light, a specific color of light, or a combination thereof.

  In one embodiment, polarization 272 of non-useful polarized light 208 can be rotated by initial and final reflectors 214 and 218 to substantially match polarization 270 of useful polarized light 204. In this example, the first orthogonal direction 206 and the second orthogonal direction 216 are substantially in the plane of the polarization 272 of the non-useful polarized light 208. Using this basic block, the non-useful polarized light 208 from the polarization beam splitter 202 is converted into the polarization 270 of the non-useful polarized light 204 into the polarization 270 of the useful polarization light 204 and output as described above. It can be reflected and redirected to be redirected to direction 206.

  In the alternative embodiment illustrated in FIG. 9, the initial reflector 214 can reflect the non-useful polarized light 208 around the plane axis of the polarization 272 and the final reflector 218 can polarize the non-useful polarization light 208. Reflection about an axis substantially perpendicular to the plane of 272 causes non-useful polarized light 208 to be polarized 270 as well. The light from the final reflector 218 passes through the spacer 246 and the now horizontally polarized non-useful polarized light 208 can exit in the same plane as the useful polarization light 204. These two outputs can be incorporated into the output light pipe 232 and homogenized so that their shape and numerical aperture (NA) are the desired shape and numerical aperture at the output surface. In one embodiment, the output light pipe 232 can also use total internal reflection to propagate light to its output.

  In one embodiment, useful polarized light 204 can exit polarizing beam splitter 202 in a direction different from that of non-useful polarized light 208 after it has been redirected to output direction 206 by final reflector 218. In one embodiment illustrated in FIG. 3A, the first output reflector 220 and the second output reflector 222 can be used to redirect the useful polarized light 204 in the same direction as the non-use polarized light 208. In another embodiment, the useful polarized light 204 is redirected by the first output reflector 220 illustrated in FIG. 4A, while the non-useful polarized light 208 is the same as the useful polarized light 204 by the second output reflector 222 illustrated in FIG. 4B. Change direction. In either case, spacer 246 can be used to allow useful polarized light 204 to exit on the same surface as non-useful polarized light 208. This may be useful for capturing useful polarized light 204 and non-useful polarized light 208 into the output light pipe 232.

  In one embodiment, the supercube 268 may comprise a polarizing beam splitter 202 and reflectors 214, 218, 220 and 222. Light can propagate through these optical components by total internal reflection. In order to promote total internal reflection, the surface of these optical components can be optically polished. In one embodiment, the optical material used for the reflectors 214, 218, 220, and 222 to promote total internal reflection of the distorted light beam can have a high refractive index. In one embodiment, the input and output surfaces of the optical component can be coated with an anti-reflective (AR) coating to minimize Fresnel reflection losses.

  In one example, the reflectors 214, 218, 220 and 222 can be made from optical glass such as SF11 (n = 1.785). In another embodiment, reflectors 214, 218, 220, and 222 can be made from optical glass such as BK7 (n = 1.517). However, in this embodiment, the light rays may begin to leak out of the walls, particularly the diagonal walls of the reflectors 214, 218, 220 and 222.

  In one embodiment, spacers 246 can be used with reflectors 214, 218, 220, and 222 to facilitate bulking and forming large cube shapes. In one embodiment, the spacer 246 can be a cube. In one embodiment, each of the reflectors 214, 218, 220 and 222 can be combined with a corresponding spacer 246, such as a right angle spacer, to form a small cube. In one embodiment, the super cube 268 can be composed of eight small cubes. In one embodiment, the reflectors 214, 218, 220 and 222 and the spacers 272 can be stacked together to form a supercube 268. In one embodiment, the components can be glued together by an adhesive. In another embodiment, the components can be held together by a physical holder. This structure is robust and can have minimal loss.

  In some embodiments, any of the input and output light pipes 224 and 232, reflectors 214, 218, 220 and 222, or polarizing beam splitter 202 may be used to promote total internal reflection and minimize losses. A void can be introduced between the two. In one embodiment, input light pipe 224, reflectors 214, 218, 220 and 222, and output light pipe 232 can be separated by a small air gap.

  In one embodiment, as illustrated in FIG. 5, the supercube 268 can be comprised of a plurality of individual components. In one embodiment, some of the components can be assembled into one unit. In one embodiment, for example, two prisms can be combined into one prism. In this embodiment, a pair of reflectors 214, 218, 220 or 222 can be assembled during the manufacturing process, for example, during the glass forming process. In another embodiment, two prisms can be bonded into one unit. In one embodiment, two prisms can be combined with half of the polarizing beam splitter 202 to form a unit. In this embodiment, a full PCS system can be composed of two components combined with spacers 246. In another embodiment, the prism can be combined with the spacer 246. In one embodiment, the system can be configured into two components with separation at polarizing beam splitter 202. In this embodiment, the cost can be minimized.

  In one embodiment, polarizing beam splitter 202 and reflectors 214, 218, 220, and 222 can be substantially cubic. In one embodiment, polarizing beam splitter 202 and reflectors 214, 218, 220, and 222 can have substantially similar dimensions on all sides, except for the hypotenuse of the reflector. In this embodiment, the output of the input light pipe 224 can be a square, and the input of the output light pipe can be a rectangle with an aspect ratio of 2: 1. A non-cubic shape in which the input of the output light pipe 232 has an aspect ratio other than 2: 1 is also possible, although the connection loss is likely to be large.

  In some embodiments, input and output light pipes 224 and 232, reflectors 214, 218, 220 and 222, or polarizing beam splitter 202 may be coated with an anti-reflection (AR) coating to increase efficiency. it can. In some embodiments, the input and output light pipes 224 and 232 can be tapered in an increasing or decreasing direction, depending on the needs of the application. The reflectors 214, 218, 220 and 222 can be suitable reflective coatings for high angle light. The super cube 268 can be used in various configurations other than those described above.

  In one embodiment, the input light pipe 224 can be located near the input 226 of the polarizing beam splitter 202. In one embodiment, the input light pipe 224 can include an input surface 228 and an output surface 230. In some embodiments, the input light pipe 224 can be formed from quartz, glass, plastic, or acrylic. In some embodiments, the input light pipe 224 may be a tapered light pipe (TLP) or a straight light pipe (SLP). In some examples, the shape of the input surface 228 can be flat, convex, concave, toroidal, or spherical. The surface of the input light pipe 224 can be coated such that the polarization is maintained by total internal reflection. The dimensions of the input surface 228 and the output surface 230 can be selected so that the output numerical aperture (NA) is compatible with the device that receives the light from the input light pipe 224.

  In one embodiment, the output surface 230 can be located near the input 226 of the polarizing beam splitter 202. In some examples, the shape of the output surface 230 can be flat, convex, concave, toroidal, or spherical. In one embodiment, the input light pipe 224 receives substantially unpolarized light at the input surface 228 and transmits the unpolarized light to the polarizing beam splitter 202 at the output surface 230.

  In one embodiment, the input light pipe 224 can be hollow. The output surface 230 can be a plano-convex lens. The convex surface of the output surface 230 can be spherical or cylindrical, depending on the final structure and cost of the component. The power of the output surface 230 can be designed so that light from the output surface 230 is imaged onto the polarizing beam splitter 202. The inner surface of the input light pipe 224 can be coated with a polarization maintaining material.

  In one embodiment, the output light pipe 232 can be located near the output 234 of the supercube 268. In one embodiment, the output light pipe 232 can include an input surface 236 and an output surface 238 that are located near the output direction 206. The output light pipe 232 can receive the useful polarized light 204 and the non-useful polarized light 208 at the input surface 236 and transmit the useful polarized light 204 and the non-useful polarized light 208 at the output surface 238.

  In some embodiments, the shape of the input surface 236 can be flat, convex, concave, toroidal, or spherical. In some examples, the shape of the output surface 238 can be flat, convex, concave, toroidal, or spherical. In some embodiments, the output light pipe 232 can be formed from a material selected from the group consisting of quartz, glass, plastic, or acrylic. In some embodiments, the output light pipe 232 may be a tapered light pipe (TLP) or a straight light pipe (SLP). The surface of the output light pipe 232 can be coated such that the polarization is maintained by total internal reflection. The dimensions of the input surface 236 and the output surface 238 can be selected such that the output numerical aperture (NA) is compatible with the device receiving the light from the output light pipe 232.

  In one embodiment, the output light pipe 232 can be hollow. The output surface 238 can be convex. The convex surface of the output surface 238 can be spherical or cylindrical, depending on the final structure and cost of the component. The power of the output surface 238 can be designed so that light from the output surface 238 is imaged onto the image projection system. The inner surface of the output light pipe 232 can be coated with a polarization maintaining material.

  In one embodiment, light from the source 212 can be reflected to the polarizing beam splitter 202 by a shell reflector 240. In one example, the shell reflector 240 can include a coating that transmits a predetermined portion of the electromagnetic radiation spectrum. This may be used to remove unavailable invisible light before it is captured in the imager. In some embodiments, the predetermined portion of the electromagnetic radiation spectrum can be infrared light, visible light, a predetermined band portion of the wavelength of light, a specific color of light, or a combination thereof. In another embodiment, the coating can reflect infrared light, visible light, a predetermined band portion of the wavelength of light, a specific color of light, or a combination thereof.

  In one embodiment, the shell reflector 240 can have first and second focal points 242, 244. In one embodiment, a source 212 of electromagnetic radiation is positioned substantially near the first focal point 242 of the shell reflector 240 to emit a ray of light reflected from the shell reflector 240, substantially at the second focal point 244. It can be configured to converge. In one embodiment, the input surface 228 can be positioned near the second focal point 244 and configured to collect and transmit substantially all of the light. In another embodiment, the input 226 of the polarizing beam splitter 202 can be positioned near the second focal point 244 and configured to collect and transmit substantially all of the light. In some embodiments, the shell reflector 240 can be at least a portion of a substantially elliptical rotation surface, a substantially spherical rotation surface, or a substantially toric rotation surface.

  In one example, the shell reflector 240 can comprise a primary reflector 250 with a first optical axis 252 and the first focal point 242 can be the focal point of the primary reflector 250. In this embodiment, the shell reflector 240 further comprises a secondary reflector 254 comprising a second optical axis 256 positioned substantially symmetrically with respect to the primary reflector 250, wherein the first and second optical axes 252 and 256 are It can be configured to be located substantially on the same line. In this embodiment, the second focal point 244 can be the focal point of the secondary reflector 254, and the light rays are reflected from the primary reflector 250 toward the secondary reflector 254 and converge substantially at the second focal point 244. It can be constituted as follows. In some embodiments, the primary and secondary reflectors 250, 254 can each be a substantially elliptical rotational surface or a substantially parabolic rotational surface.

  In one embodiment, primary reflector 250 can be at least a portion of a substantially elliptical rotational surface and secondary reflector 254 can be at least a portion of a substantially hyperbolic rotational surface. In another embodiment, primary reflector 250 can be at least a portion of a substantially hyperbolic rotational surface and secondary reflector 254 can be at least a portion of a substantially elliptical rotational surface.

  A source 212 can be placed at the first focal point 242 of the primary reflector 250 to collimate the collected light and redirect it toward the secondary reflector 254. The output at input surface 228 can be directed to input light pipe 224. In one embodiment, the input light pipe 224 can be a tapered light pipe (TLP). The input light pipe 224 may be useful for converting the cross-sectional area or numerical aperture of the source 212 image. Light can be redirected towards the supercube polarization recovery system and linearly polarized light can be obtained at the output light pipe 232. Linearly polarized light may be suitable for illumination of LCD imager chips that require polarized light.

  The degree of light collimation can depend on the size of the source 212. The secondary reflectors 254 can be arranged symmetrically with respect to the primary reflector 250 so that they have a common optical axis. The beam entering the secondary reflector 254 converges to the target, i.e., the second focus 244 where the input light pipe 224 is located. The input light pipe 224 can take in light from the second focal point 244 of the secondary reflector 254. In one example, the source 212 can be configured to be imaged onto the target at a 1: 1 ratio such that the brightness of the source 212 is substantially maintained. The image of source 212 at input surface 228 can be exactly the same as source 212 in unit magnification due to the 1: 1 symmetry of the system.

  The polarization recovery system 200 can maintain etendue throughout the source collection components of the polarization recovery system 200. The full angle of light at the input surface 228 is about 180 degrees around the axis of the source 212 and 90 degrees around the axis perpendicular to the axis of the source 212 due to the extension of the reflector. These angles may be too large for applications such as microdisplays. In one embodiment, the input light pipe 224 has a high input numerical aperture (NA) and a small input area, no loss of brightness, and thus a lower numerical aperture (NA) and higher output without reducing the angle. A tapered light pipe (TLP) can be converted into an area.

  In one embodiment, the source 212 may not be circular. In some embodiments, the input light pipe 224 input can be designed as a rectangle, ellipse, octagon, or other cross-sectional shape that matches the shape of the source 212 image. Input matching the image of the source 212 can prevent or reduce degradation of the system etendue due to shape mismatch. The output dimensions and aspect ratio of the input light pipe 224 can be designed to match the size and aspect ratio of the imager panel, but they should be relatively arbitrary in a supercube configuration. Can do.

  Primary and secondary reflectors 250, 254 may substantially cover the 180 degree rotating arc range to maximize collection efficiency. That is, the primary reflector 250 collects approximately half of the light emitted from the source 212. A retro-reflector 258 can be disposed on the opposite side of the primary reflector 250 to collect the other half of the emitted light. In one embodiment, retro-reflector 258 can be a hemispherical retro-reflector. In one embodiment, the center of curvature of the retro-reflector 258 can be located near the lamp source 212. In this embodiment, substantially all of the light can be configured to be reflected back through the source 212, collected by the primary reflector 250, and ultimately focused on the light pipe. In practice, the retroreflector 258 efficiency can be reduced by as much as 60% to 80% due to reflection losses, Fresnel reflection losses, and distortion losses from the envelope of the source 212.

  In one embodiment, the retro reflector 258 can be disposed on the opposite side of the shell reflector 240 from the source 212 side. In one example, retro-reflector 258 can be a spherical retro-reflector. In one embodiment, retro-reflector 258 can be configured integrally with shell reflector 240. In one example, retro-reflector 258 can comprise a coating that transmits a predetermined portion of the electromagnetic radiation spectrum. This may be used to remove unavailable invisible light before it is captured in the imager. In some embodiments, the predetermined portion of the electromagnetic radiation spectrum can be infrared light, visible light, a predetermined band portion of the wavelength of light, a specific color of light, or a combination thereof. In another embodiment, the coating can reflect infrared light, visible light, a predetermined band portion of the wavelength of light, a specific color of light, or a combination thereof.

  In one embodiment of the present invention, the image projection system 260 can be disposed in the vicinity of the output direction 206 to collect substantially all of the useful polarized light 204. In some embodiments, the image projection system 260 is a reflective crystal on silicon (LCOS) imager, a digital micromirror device (DMD) chip, or a transmissive liquid crystal display (LCD) panel. be able to.

  In one embodiment of the present invention, the focus lens 262 can be disposed in the vicinity of the output direction 206 with the image projection system 260 disposed in the vicinity of the output side 264 of the focus lens 262. The image 266 illuminated by the useful polarized light 204 collected and focused on the focus lens 262 is emitted by the projection system 260 to display the image 266.

  In one embodiment of the present invention, a polarization recovery method includes substantially polarizing light into usefully polarized light 204 and unuseful polarized light 208 and transmitting usefully polarized light 204 to an output direction 206. Reflecting the non-useful polarized light 208 in a first orthogonal direction 210 that is substantially orthogonal to the output direction 206; Reflecting in a second orthogonal direction 216 orthogonal to the direction 210 and reflecting unuseful polarized light 208 in the output direction 206.

  While the invention has been described in detail above, it is not intended that the invention be limited to the specific embodiments described. Of course, those skilled in the art can make various modifications to, and start with, the specific embodiments described herein without departing from the inventive concept.

Polarization recovery system Schematic of a polarization recovery system according to an embodiment of the present invention. Polarization recovery apparatus used in an embodiment of the present invention Polarization recovery apparatus used in an embodiment of the present invention Polarization recovery apparatus used in an embodiment of the present invention Linear and tapered light pipes used in embodiments of the present invention Various cross sections of light pipes used in embodiments of the present invention Various structures of light pipes used in embodiments of the present invention Polarization recovery apparatus used in an embodiment of the present invention

Claims (39)

A polarization recovery device (200) comprising:
Polarized light that transmits useful polarized light (204) in the output direction (206) and reflects non-useful polarized light (208) in a first orthogonal direction (210) that is substantially orthogonal to the output direction (206). Beam splitter (202),
An initial reflector (214) disposed so as to be reflective with respect to the first orthogonal direction (210), the initial reflector (214) transmits the non-useful polarized light (208) to the output direction (206) and the Reflecting in a second orthogonal direction (216) substantially orthogonal to the first orthogonal direction (210); and
The final reflector (218) disposed so as to be reflective with respect to the second orthogonal direction (216), the final reflector (218) reflects the non-useful polarized light (208) in the output direction (206). ,
Here, the non-useful polarized light (208) is substantially rotated to the useful polarization light (204) by the initial and final reflectors (214, 218). The polarization recovery device (200) of claim 1, further comprising:
A first output reflector (220) disposed to be reflective with respect to the output direction (206), and the first output reflector (220) transmits the useful polarized light (204) to the second orthogonal direction (216). Reflected in and
A second output reflector (222) disposed so as to be reflective with respect to the second orthogonal direction (216), the second output reflector (222) transmits the useful polarized light (204) to the output direction (206). Reflect on. The polarization recovery device (200) of claim 2, wherein the first output reflector (220) is selected from the group consisting of:
prism,
Right angle prism,
Mismatch impedance, and
mirror. The polarization recovery device (200) of claim 2, wherein the first output reflector (220) has a coating that transmits a predetermined portion of an electromagnetic radiation spectrum selected from the group consisting of:
Infrared light,
visible light,
A predetermined band portion of the wavelength of light,
Specific color light, and
A combination of these. The polarization recovery device (200) of claim 2, wherein the second output reflector (222) is selected from the group consisting of:
prism,
Right angle prism,
Mismatch impedance and
mirror. The polarization recovery device (200) of claim 2, wherein the second output reflector (222) has a coating that transmits a predetermined portion of the electromagnetic radiation spectrum selected from the group consisting of:
Infrared light,
visible light,
A predetermined band portion of the wavelength of light,
Specific color light, and
A combination of these. The polarization recovery device (200) of claim 1, further comprising:
An input light pipe (224) having an input surface (228) and an output surface (230), the output surface (230) being disposed in the vicinity of the input surface (226) of the polarizing beam splitter (202), The input light pipe (224) receives substantially unpolarized light at the input surface (228) and transmits the unpolarized light to the polarized beam splitter (202) at the output surface (230). The polarization recovery device (200) of claim 7, wherein the shape of the input surface (228) is selected from the group consisting of:
flat,
Convex,
Concave,
Toroidal and
spherical. The polarization recovery device (200) of claim 7, wherein the shape of the output surface (230) is selected from the group consisting of:
flat,
Convex,
Concave,
Toroidal and
spherical.   The polarization recovery device (200) of claim 7, wherein the input light pipe (224) is constructed from a material selected from the group consisting of quartz, glass, plastic, or acrylic. The polarization recovery device (200) of claim 7, wherein the input light pipe (224) is selected from the group consisting of:
SLP and
TLP. The polarization recovery device (200) of claim 1, further comprising:
An output light pipe (232) having an input surface (234) and an output surface (236) disposed in the vicinity of the output direction (206), and the output light pipe (232) is connected to the input surface (234) The useful polarized light (204) is received and the useful polarized light (204) is transmitted at the output surface (236). The polarization recovery device (200) of claim 12, wherein the shape of the input surface (234) is selected from the group consisting of:
flat,
Convex,
Concave,
Toroidal and spherical. The polarization recovery device (200) of claim 12, wherein the shape of the output surface (236) is selected from the group consisting of:
flat,
Convex,
Concave,
Toroidal and
spherical.   13. The polarization recovery device (200) of claim 12, wherein the output light pipe (232) is comprised of a material selected from the group consisting of quartz, glass, plastic, or acrylic. The polarization recovery device (200) of claim 12, wherein the output light pipe (232) is selected from the group consisting of:
SLP and
TLP. The polarization recovery device (200) of claim 1, wherein the initial reflector (214) is selected from the group consisting of:
prism,
Right angle prism,
Mismatch impedance, and
mirror. The polarization recovery device (200) of claim 1, wherein the initial reflector (214) has a coating that transmits a predetermined portion of an electromagnetic radiation spectrum selected from the group consisting of:
Infrared light,
visible light,
A predetermined band portion of the wavelength of light,
Specific color light, and
A combination of these. The polarization recovery device (200) of claim 1, wherein the final reflector (218) is selected from the group consisting of:
prism,
Right angle prism,
Mismatch impedance, and
mirror. The polarization recovery device (200) of claim 1, wherein the final reflector (218) has a coating that transmits a predetermined portion of the electromagnetic radiation spectrum selected from the group consisting of:
Infrared light,
visible light,
A predetermined band portion of the wavelength of light,
Specific color light, and
A combination of these. The polarization recovery device (200) of claim 1, further comprising:
A shell reflector (240) having first and second focal points (242, 244);
Located near the first focus (242) of the shell reflector (240), emits light rays reflected from the shell reflector (240) and substantially converges at the second focus (244). An electromagnetic radiation source (212),
Here, the input surface (228) of the input light pipe is disposed in the vicinity of the second focal point (244) to collect and transmit substantially all of the light. The polarization recovery device (200) of claim 21, wherein the shell reflector (240) includes at least a portion of a shape selected from the group consisting of:
A substantially elliptical rotating surface,
A substantially spherical rotating surface; and
A substantially toric rotating surface. The polarization recovery device (200) of claim 21, wherein the shell reflector (240) includes a primary reflector (250) comprising a first optical axis (252), and the first focal point (242) is the primary focus (242). The focus of the reflector (250), said shell reflector (240) further comprising:
A second optical axis (256) positioned substantially symmetrically with respect to the primary reflector (250) is provided, and the first optical axis and the second optical axis (252, 256) are substantially collinear. A secondary reflector (254) configured such that the second focus (244) is the focus of the secondary reflector (254); and
The light rays are reflected from the primary reflector (250) toward the secondary reflector (254) and converge substantially at the second focal point (244). The polarization recovery device (200) of claim 23, wherein the primary reflector (250) and the secondary reflector (254) each comprise at least a portion of a shape selected from the group consisting of:
A substantially elliptical rotational surface; and
A parabolic rotating surface. A polarization recovery device (200) according to claim 23, comprising:
The primary reflector (250) includes at least a portion of a substantially elliptical rotational surface; and
The secondary reflector (254) includes at least a portion of a substantially hyperbolic rotating surface. A polarization recovery device (200) according to claim 23, comprising:
The primary reflector (250) includes at least a portion of a substantially hyperbolic rotating surface; and
The secondary reflector (254) includes at least a portion of a substantially elliptical rotational surface. The polarization recovery device (200) of claim 23, wherein the shell reflector (240) has a coating that transmits a predetermined portion of the electromagnetic radiation spectrum selected from the group consisting of:
Infrared light,
visible light,
A predetermined band portion of the wavelength of light,
Specific color light, and
A combination of these. The polarization recovery device (200) of claim 21, further comprising:
A retro reflector disposed on the opposite side of the source side of the shell reflector (240).   29. The polarization recovery device (200) of claim 28, wherein the retro-reflector includes a spherical retro-reflector (258). The polarization recovery device (200) of claim 28, wherein the retroreflector (258) has a coating that transmits a predetermined portion of the electromagnetic radiation spectrum selected from the group consisting of:
Infrared light,
visible light,
A predetermined band portion of the wavelength of light,
Specific color light, and
A combination of these.   The polarization recovery device (200) of claim 21, wherein the electromagnetic radiation source (212) comprises an arc lamp.   32. The polarization recovery apparatus (200) of claim 31, wherein the arc lamp comprises a lamp selected from the group consisting of a xenon lamp, a metal halide lamp, a UHP lamp, a HID lamp, or a mercury lamp.   The polarization recovery device (200) of claim 21, wherein the electromagnetic radiation source (212) is selected from the group consisting of a halogen lamp and a filament lamp. The polarization recovery device (200) of claim 1, further comprising:
An image projection device (260) disposed in the vicinity of the output direction (206) to substantially collect the useful polarized light (204). The polarization recovery device (200) of claim 34, wherein the image projection device (260) is selected from the group consisting of:
LCOS imager,
DMD chip, and
Transparent LCD panel.   The polarization recovery device (200) of claim 21, wherein the shape of the polarizing beam splitter (202) is substantially matched to the aperture of the electromagnetic radiation source (212).   The polarization recovery device (200) of claim 1, wherein the polarization beam splitter (202) comprises a wire grating polarization beam splitter. A polarization recovery method comprising the following steps:
Substantially polarizing light into useful polarized light (204) and non-useful polarized light (208);
Transmitting the useful polarized light (204) in the output direction (206);
Reflecting the non-useful polarized light (208) in a first orthogonal direction (210) substantially orthogonal to the output direction (206);
Reflecting the non-useful polarized light (208) in a second orthogonal direction (216) substantially orthogonal to the output direction (206) and the first orthogonal direction (210); and
The non-useful polarized light (208) is reflected in the output direction (206). A polarization recovery system comprising:
Means for substantially polarizing light into useful polarized light (204) and non-useful polarized light (208);
Means for transmitting said useful polarized light in the output direction (206);
Means for reflecting the non-useful polarized light in a first orthogonal direction (210) substantially orthogonal to the output direction (206);
Means for reflecting the non-useful polarized light in a second orthogonal direction (216) substantially orthogonal to the output direction (206) and the first orthogonal direction (210); and
Means for reflecting the non-useful polarized light in the output direction (206).

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