HIGH EFFICIENCY HOMOGENEOUS POLARIZATION CONVERTER

Abstract: A polarization converter for polarizing a light beam by converting all light waves to the same orientation comprises: 1) a first beam dividing matrix (32) of refractory material for dividing a single, large light beam (34) into smaller sub-beams (36), 2) a second beam focusing matrix (37) for polarizing select portions of the sub-beams, and 3) a series of narrow and shallow polarizing cells. The second beam focusing matrix further comprises a plurality of concave lenses (48) for redirecting each sub-beam and quarter wave retarders (54) disposed in alignment with, and adjacent to, the reflective side of an equal plurality of mirror segments. The polarizing cells include either a first beamsplitter or a second beamsplitter, where the first beamsplitters and second beamsplitters are disposed in opposing diagonal fashion and in an alternating manner. Lightwaves of a selected polarization pass directly through the first beamsplitter and out of the polarizing cell, while all other lightwaves are horizontally reflected by the first beamsplitter and directed onto the second beamsplitter where they are redirected toward the quarter wave retarder. The reflected light passes through the quarter wave retarder, reflects off of the mirror and again passes through the quarter wave retarder.

Description: HIGH EFFICIENCY HOMOGENEOUS POLARIZATION CONVERTER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to light polarization, and more particularly to an apparatus for converting non-polarized light into polarized light, where an array of small polarizing cells comprises a flat, molded panel having a reduced thickness and reduced weight, where the panel provides a highly efficient means for polarizing light. 2. Description of the Background Art Linearly polarized light is light for which the spatial orientation of its electric field lies entirely within one plane. The conventional approach to linearly polarizing light is to use a filter that simply absorbs light of the wrong polarization, passing only light of a chosen linear polarization. This results in linearly polarized light, but at the cost of losing over fifty percent of the incident light available. Subsequent improvements to polarizing light include use of a beamsplitter and a retarder instead of a filter. See U.S. Patent No. 5,283,600. In the prior art, a beam of light is directed to a beamsplitter, where light of the desired polarization passes directly through the beamsplitter and out the exit, while the rest of the light (light not of the desired polarization) is reflected horizontally to an adjacent mirror. The light is again reflected and passes vertically through a half-wave retarder which rotates the axis of orientation of the light to the desired polarization. The main disadvantage of this system is size. The size of the beamsplitter must be greater than or equal to the size of the incoming beam of light in order to accommodate and process all of the available light. Further, the exiting light beam is twice the width of the incoming non-polarized light, as light exits through both the beamsplitter and the adjacent retarder. Therefore, the larger the beam of incoming light, such as that used for an overhead projection system, the larger the polarizer must be to accommodate the incoming beam. Such a large size is undesirable for laptop computers and other small-sized component applications. What is needed is a small, flat, lightweight panel suitable for laptop computers and overhead projectors that comprises a series of narrow, shallow polarizing cells that will polarize all of the incident light in a light beam. SUMMARY OF THE INVENTION The present invention is a high efficiency homogenous polarization converter for polarizing the spatial orientation of the electric field in a light beam by converting all light waves to the same orientation. The polarization converter of the present invention preferably comprises a first beam dividing matrix of refractory material for dividing a single, large light beam into smaller sub-beams. The first beam dividing matrix further comprises rows of adjacently disposed convex cylindrical lenses. As a light beam is transmitted through the first matrix, the lenses cause the light beam to be broken up into a plurality of smaller sub-beams by refracting the light passing through each lens to create a plurality of sub- beams. Each sub-beam is equal in size to the lens 1 cross-sectional width, and the width of the sub-beams gradually narrows as the light travels farther away from the lens. The parallel formation of the lenses comprising the first matrix assures that every portion of the incoming light beam passing therethrough is captured and refracted into one of the many sub-beams. The polarization converter of the present invention also preferably comprises a second beam focusing matrix of refractory material combined with means for reorienting select portions of the sub-beams. The second beam focusing matrix further comprises a plurality of concave lenses, for redirecting each sub-beam, and means for reorienting the s-wave components within the sub-beams to change them into p-wave orientation. The sub- beams from the first matrix are directed onto the lenses of the second matrix, where the lenses collimate the sub-beams so that the light rays comprising each resultant sub-beam are disposed in parallel. The reorienting means are integrated in alternating arrangement with the concave lenses, and comprise quarter wave retarders in alignment with, and adjacent to, the reflective side of an equal plurality of mirror segments. The polarization converter of the present invention further preferably comprises a series of narrow and shallow polarizing cells, disposed in rows. Each polarizing cell further includes either a first beamsplitter or a second beamsplitter, where the first beamsplitters and second beamsplitters are disposed in opposing diagonal fashion and in an alternating manner. The polarizing cells are aligned with the second matrix such that the resultant sub- beams from the lenses of the second matrix are directed into a polarizing cell having a first beamsplitter. Likewise, each polarizing cell having a second beamsplitter is aligned with one of the plurality of reorienting means. In operation, a light beam passing through the convex cylindrical lenses of the first matrix produces discrete sub-beams having ever narrowing beam widths. The sub-beams are focused onto corresponding lenses in the second matrix. The corresponding lenses again refract the sub-beams, to cause parallel alignment of the light rays comprising the resultant sub-beam. The resultant sub-beam is directed into the polarizing cell having the first beamsplitter. Lightwaves having p-wave polarization pass directly through the first beamsplitter and out of the polarizing cell. Lightwaves having s- wave polarization (all other lightwaves) will be horizontally reflected by the first beamsplitter and directed onto the second beamsplitter. The second beamsplitter, in turn, once again reflects the s-waves, and directs them toward the polarizing means. The s-waves pass through the quarter wave retarder, where the wavelength of each s-wave is delayed by one-quarter, causing the s- waves to become circularly polarized. The s-waves then reflect off of the mirror and again pass through the quarter wave retarder, which returns the s- waves to a linear polarization from their circular polarization. The s-waves are again delayed by one quarter, thus converting the effective rotation axis ninety degrees as a result of the two passes through the quarter-wave retarder. Thus, the s-waves are now re-orientated as p-waves as the result of being rotated ninety degrees. The re-oriented p-waves pass through the second beamsplitter and exit the polarizing cell. The re-oriented p-waves join the original p-waves exiting the polarizing cells having the first beamsplitter to form a full beam of polarized light. The first matrix, second matrix and polarizing cells are disposed in parallel planes and combined into a single unit. Such a unit can be manufactured in a mass-producible manner by a combination of conventional lens molding and vacuum deposition processes. The panel overcomes the size and weight problems of the conventional polarizer by utilizing a series of narrow, shallow polarizing cells. The reduction in thickness results in a very substantial reduction in weight. By using a series of polarizing cells, the panel can be produced as a flat, lightweight molded unit, suitable for laptop computers, overhead projectors, or anywhere a lightweight, efficient source of polarized light is needed. BRIEF DESCRIPTION OF THE DRAWINGS FIG. la is a cross-section of a portion of a preferred light concentrator in accordance with the present invention. FIG. lb is a perspective view of the light concentrator of FIG. la, illustrating the physical form of the component layers. FIG. 2a is a cross-section of a high efficiency homogenous polarization converter in accordance with the present invention, which utilizes the light concentrator of FIG. la along with a novel lightwave polarizing cells. FIG. 2b is a perspective view of a polarization converter formed in a panel embodiment, illustrating the association of the two layer light concentrator and the polarizing cells. FIG. 2c is a perspective view of the three layer panel of FIG. 2b, where the first beam dividing matrix is broken away to show the configuration of the second beam focusing matrix, and the second beam focusing matrix is further broken away to illustrate the configuration of the polarizing cells. FIG. 3 is a schematic of a projection system utilizing the high efficiency homogenous polarization converter of the present invention. FIG. 4 is an alternative embodiment of the polarization converter of FIG. 2a having recessed lenses and mirrored walls for conserving scattered light. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. la, a light concentrator 29 comprises a first beam dividing matrix 32 for dividing a single, large light beam 34 into smaller sub- beams 36, and a second beam focusing matrix 37 for collimating the concentrated light to provide collimated beams 36 * . The first beam dividing matrix 32 further comprises a series of adjacently disposed convex cylindrical lenses 46a-b, where the convex cylindrical lenses 46a-b are aligned in rows to form the first beam dividing matrix 32, commonly referred to as a lenticular array. As the light beam 34 is transmitted through the first beam dividing matrix 32, the convex cylindrical lenses 46a-b cause the light beam 34 to be broken up into a plurality of smaller sub-beams 36. This is done by refracting the light passing through each convex cylindrical lens 46a-b to create a plurality of sub-beams 36, each sub- beam 36 being initially equal in size to the lens' width. Because the light is refracted, the width of the sub-beams 36 gradually narrows and concentrates the light as the light travels farther away from the convex cylindrical lenses 46a-b. The compact grouping of the convex cylindrical lenses 46a-b comprising the first beam dividing matrix 32 assures that substantially all of the incoming light beam 34 is captured and refracted into one of the many sub-beams 36. The second beam focusing matrix 37 comprises a plurality of concave lenses 48 that are approximately one-half of the width of the convex cylindrical lenses 46a-b associated with the first beam dividing matrix 32. The concave lenses 48 are disposed in spaced-apart fashion such that each concave lens 48 intercepts a concentrated sub-beam 36 from the first beam dividing matrix 32. The distance between the second beam focusing matrix 37 and the first beam dividing matrix 32 is preferably the distance at which the concentration ratio of the light is 2:1. In other words, each concave lens 48 of the second beam focusing matrix 37 is positioned to intercept a sub-beam 36 at the point at which the width of the sub-beam 36 is one-half of its original width as it first leaves the first beam dividing matrix 32. Referring now to FIG. lb, a perspective view of the light concentrator 29 of FIG. la is shown to better illustrate the light concentrator's physical form. The series of adjacently disposed convex cylindrical lenses 46a-b (lenticular array) comprising the first beam dividing matrix 32 resides in a first plane. The series of spaced-apart concave lenses 48 comprising the second beam focusing matrix 37 is shown in a second plane, where the second plane is parallel to the first plane. The concave lenses 48 are aligned with the convex cylindrical lenses 46a-b such that the concentrated sub-beams 36 from the convex cylindrical lenses are intercepted by the concave lenses 48. The light concentrator 29 is typically manufactured as a panel 47, where the first beam dividing matrix 32 and the second beam focusing matrix 37 are joined about the panel's perimeter by sides 49. In the prior art, a beam of light from a light source is aimed directly upon a polarization converter. Whether the polarization converter is comprised of a single input cell or multiple cells portions of the light will fall outside of the entrance to the input cell. The systems of the prior art are inherently inefficient, as not all of the light is captured and used in the polarization converter. Referring now to FIG. 2a, a cross-section of a segment of cells comprising a high efficiency homogeneous polarization converter 30 in accordance with the present invention is shown. A modified version of the light concentrator 29 shown in FIG. la is used in the preferred embodiment of the polarization converter 30 of the present invention. The polarization converter 30 of the present invention comprises a first beam dividing matrix 32, a second beam focusing matrix 38 that includes orientation converters 40 for converting select portions of the sub-beams 36, and a series of narrow and shallow polarizing cells 44a-d. The first beam dividing matrix 32 comprises a series of convex cylindrical lenses 46a-b and is described with respect to FIG. la. The second beam focusing matrix 38, however, further comprises a plurality of concave lenses 48 for collimating each sub-beam 36 and orientation means 40 for converting the s-wave 50 light components within each collimated beam 36' to change them into a p-wave 52 orientation. The width of the concave lenses 48 in the second beam focusing matrix 38 are approximately one-half the width of the convex cylindrical lenses 46a-b of the first beam dividing matrix 32. The sub-beams 36 from the first beam dividing matrix 32 are directed onto the concave lenses 48 of the second beam focusing matrix 38. The concave lenses 48 collimate the sub-beams 36 so that the light rays comprising each collimated beam 36' are disposed generally in parallel. The collimated beams 36' exiting the concave lenses 48 are directed into the polarizing cells 44a-d. The orientation converters 40 comprise quarter-wave retarders 54 in alignment with, and adjacent to, the reflective side 56 of an equal plurality of mirror segments 58. The concave lenses 48 are integrated in alternating arrangement with the orientation converters 40. Further, the concave lenses 48 and orientation converters 40 comprising the second beam focusing matrix 38 lay in a single plane which is parallel to the plane of the first beam dividing matrix 32, such that the second matrix's concave lenses 48 receive the refracted sub-beams 36 from the first beam dividing matrix 32. In an alternative embodiment, discussed below with respect to FIG. 4, the concave lenses 48 and orientation converters 40 alternatively lay in parallel planes. The polarizing cells 44a-d are disposed in rows. Each polarizing cell 44a- d further includes either a first beamsplitter 60 or a second beamsplitter 62, where the first beamsplitters 60 and second beamsplitters 62 are disposed in opposing diagonal fashion and in an alternating manner. The polarizing cells 44a-d are aligned with the second beam focusing matrix 38 such that the collimated beams 36' are directed into a polarizing cell 44a, 44c having a first beamsplitter 60. Likewise, each polarizing cell 44b, 44d having a second beamsplitter 62 is aligned with one of the plurality of orientation converters 40. As the second beam focusing matrix 38 is comprised of alternating concave lenses 48 and orientation converters 40, and the polarizing cells 44a-d are comprised of alternating first beamsplitters 60 and second beamsplitters 62. The alignment of any one of the second matrix's concave lenses 48 with any one of the first beamsplitter polarizing cells 44a, 44c will cause the orientation converters 40 of the second beam focusing matrix 38 to be in alignment with a corresponding second beamsplitter polarizing cell 44b, 44d. In operation, a light beam 34 passing through the convex cylindrical lenses 46a-b of the first beam dividing matrix 32 produces discrete sub-beams 36 having ever narrowing beam widths. The sub-beams 36 are portions of the light beam 34 that are partitioned therefrom into a series of parallel beams (the sub-beams 36). The sub-beams 36 are concentrated (narrowed) to focus onto corresponding concave lenses 48 in the second beam focusing matrix 38. The surface area of the narrowed sub-beams 36 at the concave lenses 48 is approximately one-half of the width of the sub-beam 36 proximate the convex cylindrical lenses 46a-b. Thus, the concentration ratio of the sub-beams 36 is preferably two times, in order to minimize the astigmatic distortion caused by the narrowing. In other words, the width of the sub-beam 36 passing through the convex cylindrical lenses 46a-b is preferably two times greater than the width of the same sub-beam 36 as is reaches the concave lenses 48. The concave lenses 48 collimate the sub-beams 36, to cause parallel alignment of the light rays comprising the collimated beam 36'. The collimated beam 36' is directed into the polarizing cell 44a, 44c having the first beamsplitter 60. Lightwaves having a p-wave polarization 52 pass directly through the first beamsplitter 60 and out of the polarizing cell 44a, 44c. Lightwaves having an s-wave polarization 50 (all other lightwaves) will be horizontally reflected by the first beamsplitter 60 and directed onto the second beamsplitter 62. The second beamsplitter 62, in turn, once again reflects the s- waves 50, and directs them toward the orientation converters 40. In essence, as the s-waves 50 encounter the first beamsplitter 60, they are reflected at a ninety degree angle toward the second beamsplitter 62. Once encountering the second beamsplitter 62, the s-waves 50 are again reflected at a ninety degree angle, whereby they then travel in a direction that is opposite the direction at which they entered the first beamsplitter polarizing cell 44a, 44c. The s-waves 50 pass through the quarter wave retarder 54, where the wavelength of each s-wave 50 is delayed by one-quarter, effectively causing the s-waves 50 to become circularly polarized in either a right-handed or left- handed circular polarization. The s-waves 50 then reflect off of the mirror 58 which changes the direction (handedness) of the circular polarization, and again pass through the quarter wave retarder 54. The second pass through the quarter wave retarder 54 returns the s-waves 50 to a linear polarization from their circular polarization, but with an effective ninety degree rotation of axis, as a result of the two passes of the s-waves 50 through the quarter-wave retarder 54. As a result of the double pass of the s-waves 50 through the quarter wave retarder 54, the s-waves 50 are now re-oriented as p-waves 52'. Following the re-orientation of the s-waves 50 to p-waves 52', the re- oriented p-waves 52' pass through the second beamsplitter 62 and exit the polarizing cell 44b, 44d. The re-oriented p-waves 52' join the original p-waves 52 exiting the polarizing cells 44a, 44c, and thus form a full beam of polarized light 64. Referring now to FIG. 2b, a perspective view of the polarization converter 30 of FIG. 2a is shown formed in a panel 66 embodiment. The first beam dividing matrix 32, second beam focusing matrix 38 and polarizing cells 44a-d are disposed in parallel planes and constructed as a single unit. The panel 66 is held together by sides 67. The panel 66 can be manufactured in a mass-producible manner by a combination of conventional lens molding and vacuum deposition processes. Referring now to FIG. 2c, illustrated is a perspective view of the three layer panel 66 of FIG. 2b, broken away. The first beam dividing matrix 32 is broken away to show the configuration of the second beam focusing matrix 37. The second beam focusing matrix 37 is further broken away to illustrate the configuration of the polarizing cells 44. Referring now to FIG. 3, a schematic of a projection system 68 utilizing the polarization converter 30 of the present invention is shown. Light 69 from a lamp source 70 is collimated by a first Fresnel lens 72, and directed toward the polarization converter 30. As discussed in detail with respect to FIG. 2a, the high efficiency homogenous polarization converter 30 linearly polarizes the collimated light 71. Locating the first Fresnel lens 72 between the lamp source 70 and the polarization converter 30 provides that the light hitting the polarization converter 30 is comprised of parallel light rays. The efficiency and effectiveness of the beamsplitters are maximized where the incoming light rays are parallel. The polarized light 73 passes through a second Fresnel lens 74 which condenses and concentrates the light. The polarized light 73 then passes through a display LCD 76 and a conventional analysis polarizer 78. The LCD 76 imparts an image by projecting an object plane, and can alternatively be positioned between the polarization converter 30 and the second Fresnel lens 74. The analysis polarizer 78, the polarization converter 30 and the LCD 76 provide visible contrast differences that are projected as an image onto a screen (not shown). The LCD 76 is typically composed as a matrix display using twisted nematic or super-twisted nematic liquid crystal material which requires a polarizer and an analyzer to be able to display an image with contrast. The analysis polarizer 78 is preferably a conventional stretched and dyed film, typically made of poly-vinyl alcohol. The polarized light 75 passing through the LCD 76 and analysis polarizer 78 converges at the projection lens 80 and diverges beyond the projection lens 80. A folding mirror 82 typically disposed at a 45 degree angle, directs the polarized light 75 toward a projection screen or blank wall (not shown) for viewing. Use of the folding mirror 82 allows the elevation of the projected image to be changed, such as in an overhead projector, so as to position the image at the best height for viewing by the intended audience. Referring now to FIG. 4, an alternative embodiment of a polarization converter 30' of FIG. 2a is shown. The concave lenses 48 are recessed with respect to the orientation converters 40. Walls 84 are provided to span the distance between the concave lenses 48 and the orientation converters 40. The walls 84 are mirrored to conserve scattered light. Although the collimated beams 36' passing through the concave lenses 48 are generally parallel, some scattered rays of light will pass at an angle. The scattered light is reflected by the mirrored walls 84 and directed back in toward the collimated beam 36'. In this manner, the scattered light in conserved and used by the polarization converter 30' to polarize the maximum amount of light available. The invention has now been explained with reference to specific embodiments. Other embodiments will be apparent to those of ordinary skill in the art in light of this disclosure. For example, although the described embodiment illustrates the use of refractory material in the first beam dividing matrix and second beam focusing matrix, holographic means for concentrating the light may equivalently be used. Therefore, it is not intended that this invention be limited, except as indicated by the appended claims.

Claims: What is claimed is: 1. A two-stage light concentrator for dividing a beam of light into a plurality of concentrated sub-beams comprising: means for dividing a single, generally parallel beam of light into a plurality of sub-beams and concentrating the light within each sub-beam to provide the sub-beam with an ever narrowing diameter; means for collimating the refracted light of the sub-beams to return the light to a generally parallel disposition, the means for collimating being disposed to cooperatively receive the sub-beams from the means for dividing; and polarization means for separating light of a first polarization from light of a second polarization, and re-orienting the light of the second polarization to match that of the first polarization, the polarization means disposed to receive the collimated sub-beams from the collimating means. 2. The light concentrator of Claim 1 wherein the means for dividing further comprise a first lens array for dividing the beam of light into a plurality of sub-beams, whereby each lens refracts a portion of the beam of light to create a plurality of sub-beams, each sub-beam having a first diameter proximate the lens and second diameter distal to the lens, the refraction of the sub-beams causing the light to be concentrated such that the second diameter is less than the first diameter. 3. The light concentrator of Claim 2 wherein the means for collimating further comprises a second lens array disposed to intercept the plurality of sub- beams from the first lens array, whereby each lens of the second lens array collimates the refracted light into a generally parallel disposition. 4. The light concentrator of Claim 2 wherein the first lens array refracts the light in order to reduce the diameter of each sub-beam and to increase the concentration of the light within the sub-beam as the sub-beam reaches the means for collimating. 5. The light concentrator of Claim 2 wherein the first lens array comprises rows of convex cylindrical lenses. 6. The light concentrator of Claim 3 wherein the second lens array comprises rows of concave lenses. 7. The light concentrator of Claim 3 wherein the second diameter of the sub-beam is the diameter of the sub-beam at the second lens array, the first lens array refracting the sub-beam at such an angle that the second diameter is half that of the first diameter, and each lens comprising the second lens array is approximately one half of the size of the lenses comprising the first lens array in order to accommodate the reduced diameter of the sub-beam. 8. A polarization converter for the efficient conversion of non-polarized light to polarized light, comprising: an array of polarizing cells for separating the non-polarized light into s-waves and p-waves, the s-waves being redirected; and means for polarizing the s-waves comprising a mirror having a reflective side and a quarter wave retarder disposed adjacent the reflective side of the mirror, where the redirected s-waves pass through the quarter wave retarder, are reflected off of the mirror and again pass through the quarter wave retarder resulting in reoriented s-waves. 9. The polarization converter as recited in Claim 8 wherein the array of polarizing cells further comprises a first cell containing a first beamsplitter positioned diagonally therewithin which receives non-polarized light from a light source, and reflects the s-wave component of the non-polarized light. 10. The polarization converter as recited in Claim 9 wherein the array of polarizing cells further comprises a second cell adjacent the first cell, the second cell containing a second beamsplitter positioned diagonally opposite the first beamsplitter and receives the s-waves reflected from the first beamsplitter. 11. The polarization converter as recited in Claim 10 wherein the disposition of the first and second cells is repeated throughout the array. 12. The polarization converter as recited in Claim 11 wherein a plurality of collimating lenses are disposed in alternating arrangement with the polarizing means as a table in a first plane, in order to provide a beam focusing matrix. 13. The polarization converter as recited in Claim 12 wherein collimating lenses of the beam focusing matrix are aligned with the first cells of the array of polarizing cells such that the non-polarized light passing through the collimating lenses is directed into the first cells. 14. The polarization converter as recited in Claim 12 further comprising a beam dividing matrix including a plurality of convex dividing lenses for refracting a beam of light passing through the lens to create a plurality of sub- beams which focus the light onto the collimating lenses. 15. The polarization converter as recited in Claim 14 wherein the beam dividing matrix is disposed in a second plane that is in a parallel relationship with the first plane. 16. A polarization converter comprising: a beam dividing matrix having a plurality of convex dividing lenses for refracting portions of a beam of light passing therethrough, the beam dividing matrix laying in a first plane; a beam focusing matrix having a plurality of concave directing lenses laying in a second plane, the beam focusing matrix being disposed to receive the refracted portions of the beam of light from the beam dividing matrix; an array of polarizing cells laying in a third plane for separating the light from the beam focusing matrix into s-waves and p-waves further comprising: a first cell containing a first beamsplitter positioned diagonally within the first cell, the first cell receiving the polarized light, passing the p-waves through the beam splitter and reflecting the s-waves; and a second cell disposed adjacent the first cell, the second cell containing a second beamsplitter positioned diagonally opposite the first beamsplitter, the second cell receiving the s-waves from the first cell and reflecting the s-waves, where the formulation of adjacent first and second cells is repeated throughout the array; and means for converting the orientation of the s-waves to p-waves, the converting means being disposed to receive the s-waves reflected from the second cell. 17. The polarization converter as recited in Claim 16 wherein the first, second and third planes are parallel. 18. The polarization converter as recited in Claim 16 wherein the converting means further comprise a mirror having a reflective side and a quarter wave retarder disposed adjacent the reflective side of the mirror, such that the reflected s-waves pass through the quarter wave retarder to the mirror, reflect off of the mirror and again pass through the quarter wave retarder. 19. The polarization converter as recited in Claim 18 wherein the converting means are disposed in alternating arrangement with the plurality of concave directing lenses of the beam focusing matrix. 20. The polarization converter as recited in Claim 19 wherein the converting means and concave directing lenses are co-planar. 21. The polarization converter as recited in Claim 19 wherein the concave directing lenses are recessed with respect to the converting means and walls are provided between the concave directing lenses and the converting means. 22. The polarization converter as recited in Claim 21 wherein the walls are mirrored to redirect scattered portions of the beam of light. 23. A method of converting non-polarized light into polarized light comprising the steps of: directing non-polarized light into a first cell; separating the non-polarized light into s-wave and p-wave components; redirecting the s-wave components toward a polarizer; and re-orienting the s-wave components to convert them into p-wave components by twice passing the s-wave components through a quarter wave retarder. 24. The method of converting as recited in Claim 23 further comprising the step of: collimating the converted s-waves and the p-waves to provide a polarized beam of light. 25. The method of converting as recited in Claim 23 wherein the non¬ polarized light is divided into sub-beams by refracting portions of the non- polarized light. 26. The method of converting as recited in Claim 23 wherein the step of separating the non-polarized light involves a first beamsplitter that passes the p-wave components therethrough unchanged while reflecting the s-wave components. 27. The method of converting as recited in Claim 23 wherein the step of redirecting the s-wave components involves a second beamsplitter which reflects the s-waves and directs them toward the quarter wave retarder. 28. The method of converting as recited in Claim 23 wherein the s-wave components pass through the quarter wave retarder once, reflect off of an adjacent mirror, and pass through the quarter wave retarder a second time.

Inventors: CONNER ARLIE R, HINMAN BRIAN L, RODMAN JEFFREY C, ROMANO PASQUALE, CONNER, ARLIE, R., HINMAN, BRIAN, L., RODMAN, JEFFREY, C., ROMANO, PASQUALE
Applicants: POLYCOM INC, POLYCOM, INC.
Application year: 1996
Main classification: G03B5
IPC codes: G02B5, G02B27, G02F1