# US 11,994,703 B2 · Compact spatial light modulator projection system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,994,703 B2 - Document ID: US11994703B2 - Status: Granted - Kind: B2 - Application number: 16/874,115 - Filed: 2020-05-14 - Published: 2020-11-26 - Granted: 2024-05-28 - Earliest claimed: 2019-05-20 - Assignees: Meta Platforms Technologies, LLC - Applicants: Meta Platforms Technologies, LLC - Inventors: Andrew John Ouderkirk; Tanya Malhotra; Weichuan Gao - Web page: https://patentgrep.com/patent/US11994703B2 ## CPC - G02B 5/3025: {Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state (G02B5/3008, G02B5/3016 take precedence)} - G02B 5/3016: {involving passive liquid crystal elements (optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528)} - G02B 27/0101: {characterised by optical features (G02B27/0172 takes precedence)} - G02B 27/0172: {characterised by optical features} - G02B 27/148: {including stacked surfaces having at least one double-pass partially reflecting surface} - G02B 27/283: {used for beam splitting or combining} - G03H 1/0248: {Volume holograms} - H04N 9/3102: {using two-dimensional electronic spatial light modulators (micromechanical modulators as such G02B26/0833; liquid crystal modulators as such G02F1/13)} - H04N 9/3167: {for polarizing the light beam (polarizing optical systems per se G02B27/28)} - G02B 2027/0178: {Eyeglass type (eyeglass details G02C)} - G03H 2001/0264: {Organic recording material} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G03H: HOLOGRAPHIC PROCESSES OR APPARATUS (holograms, e.g. point holograms, used as ordinary optical elements G02B5/32; producing stereoscopic or other three-dimensional effects G02B30/00; diffraction-grating systems G02B27/44; systems using moiré fringes G02B27/60; optical logic elements G02F3/00; stereo-photography G03B35/00; photosensitive materials or processes for photographic purposes G03C; {stereo-photographic or similar processes G03C9/00}; apparatus for processing exposed photographic materials G03D; analogue computers performing mathematical operations with the aid of optical elements G06E3/00; authentication by radiation, of concealed information carried by holograms or diffraction gratings G06K19/16; holographic storage G11B7/0065, G11C13/04; {stereoscopic or other three dimensional effects in television systems H04N13/00}) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An optical device includes a first polarization selective reflector positioned relative to a spatial light modulator; and a first reflective assembly positioned relative to the first polarization selective reflector so that the first polarization selective reflector receives first light from the spatial light modulator and directs at least a portion of the first light having a first polarization toward the first reflective assembly as second light. The first reflective assembly receives the second light from the first polarization selective reflector and directs at least a portion of the second light toward the first polarization selective reflector as third light having a second polarization. The second polarization is distinct from the first polarization. ## Claims ### Claim 1 An optical device, comprising: a first polarization selective reflector positioned relative to a spatial light modulator; and a first reflective assembly positioned relative to the first polarization selective reflector so that the first polarization selective reflector receives first light from the spatial light modulator and directs at least a portion of the first light having a first polarization toward the first reflective assembly as second light, and the first reflective assembly receives the second light from the first polarization selective reflector and directs at least a portion of the second light toward the first polarization selective reflector as third light having a second polarization, wherein the second polarization is distinct from the first polarization. ### Claim 2 (depends on 1) The optical device of claim 1, wherein: the spatial light modulator is positioned in a first direction from the first polarization selective reflector; the first reflective assembly is positioned in a second direction from the first polarization selective reflector; illumination light enters the optical device in a third direction from the first polarization selective reflector; and a waveguide is positioned in a fourth direction from the first polarization selective reflector, wherein the first direction and the second direction are distinct from each other. ### Claim 3 (depends on 2) The optical device of claim 2, wherein: the first direction is perpendicular to the third direction; and the second direction is perpendicular to the fourth direction. ### Claim 4 (depends on 2) The optical device of claim 2, wherein: the second direction is perpendicular to the third direction; and the first direction is perpendicular to the fourth direction. ### Claim 5 (depends on 2) The optical device of claim 2, further comprising a first reflector, wherein: the first reflector defines an opening; and the first reflector is positioned relative to the spatial light modulator so that the spatial light modulator receives light that has (i) passed through the opening of the first reflector and (ii) subsequently reflected off the first reflector. ### Claim 6 (depends on 5) The optical device of claim 5, further comprising a second polarization selective reflector disposed adjacent to the waveguide, wherein the second polarization selective reflector is configured to reflect light having a polarization different from a polarization of light reflected by the first polarization selective reflector. ### Claim 7 (depends on 5) The optical device of claim 5, further comprising a second polarization selective reflector disposed adjacent to the waveguide, wherein the second polarization selective reflector is configured to reflect light having a polarization identical to a polarization of light reflected by the first polarization selective reflector. ### Claim 8 (depends on 1) The optical device of claim 1, wherein: a first plane defined by the first polarization selective reflector intersects a second plane defined by the spatial light modulator at a first acute angle. ### Claim 9 (depends on 1) The optical device of claim 1, wherein the first reflective assembly comprises a polarization retarder and a reflective lens. ### Claim 10 (depends on 1) The optical device of claim 1, wherein: a projection of the first polarization selective reflector on a plane defined by the spatial light modulator has a rectangular shape. ### Claim 11 (depends on 10) The optical device of claim 10, wherein: the first polarization selective reflector is at substantially 45-degree angle relative to the plane defined by the spatial light modulator. ### Claim 12 (depends on 1) The optical device of claim 1, wherein: the optical device comprises a first prism and a second prism; at least a portion of the first prism has a trapezoidal cross-section having a first edge, a second edge, a third edge, and a fourth edge; the first edge is perpendicular to the second edge; the second prism is a right-angle prism having a hypotenuse; and the first polarization selective reflector is disposed between the first prism and the second prism, parallel to the hypotenuse of the second prism and the fourth edge of the first prism. ### Claim 13 (depends on 1) The optical device of claim 1, wherein the first reflective assembly is positioned relative to the spatial light modulator so that the first polarization selective reflector directs the second light toward the first reflective assembly by transmitting the second light. ### Claim 14 (depends on 1) The optical device of claim 1, wherein the first reflective assembly is positioned relative to the spatial light modulator so that the first polarization selective reflector directs the second light having the first polarization toward the first reflective assembly by reflecting the second light. ### Claim 15 (depends on 1) The optical device of claim 1, wherein the first reflective assembly comprises a reflector and a polarization retarder disposed adjacent to the reflector. ### Claim 16 (depends on 15) The optical device of claim 15, wherein the polarization retarder comprises a quarter-wave plate. ### Claim 17 (depends on 15) The optical device of claim 15, wherein the polarization retarder is disposed on a first surface of a lens and the reflector comprises a reflective coating disposed on an opposing second surface of the lens. ### Claim 18 A method, comprising: directing, using a first polarization selective reflector, first light from a spatial light modulator toward a first reflector assembly; receiving, using the first reflector assembly, the first light and directing at least a portion of the first light toward the first polarization selective reflector as second light; and receiving, using the first polarization selective reflector, the second light and directing at least a portion of the second light toward a waveguide, wherein: the first light has a first polarization, and the second light has a second polarization distinct from the first polarization. ### Claim 19 (depends on 18) The method of claim 18, wherein the first polarization selective reflector transmits the first light toward the first reflector assembly. ### Claim 20 (depends on 18) The method of claim 18, wherein the first polarization selective reflector reflects the first light toward the first reflector assembly.