# US 12,181,785 B2 · Image projector using a phase image generator > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,181,785 B2 - Document ID: US12181785B2 - Status: Granted - Kind: B2 - Application number: 18/395,844 - Filed: 2023-12-26 - Published: 2024-04-25 - Granted: 2024-12-31 - Earliest claimed: 2019-12-19 - Assignees: Lumus Ltd. - Applicants: Lumus Ltd. - Inventors: Ronen Chriki; Eitan Ronen; Yochay Danziger; Shimon Grabarnik; Tsion Eisenfeld - Web page: https://patentgrep.com/patent/US12181785B2 ## CPC - G03B 21/147: {Optical correction of image distortions, e.g. keystone} - G02B 27/0093: {with means for monitoring data relating to the user, e.g. head-tracking, eye-tracking} - G02B 27/0103: {comprising holographic elements} - G02B 27/48: Laser speckle optics - G03B 21/005: {Projectors using an electronic spatial light modulator but not peculiar thereto} - G03B 21/2033: {LED or laser light sources} - G03B 21/206: {Control of light source other than position or intensity} - G03B 21/2066: {Reflectors in illumination beam (in projection beam G03B21/28)} - G03B 21/208: {Homogenising, shaping of the illumination light} - G03B 21/28: Reflectors in projection beam {(in illumination beam G03B21/2066)} - G02B 2027/0105: {Holograms with particular structures} - G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D) - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract An image projector with a high optical efficiency projects an image at an arbitrary distance from an observer. The image projector includes an illumination module having at least one spatially coherent light source; a phase image generator with an array of optical phase shifting elements; an electronic image controller connected electrically to the phase image generator; and a waveguide which includes at least one embedded partial reflector. The waveguide may be positioned either between the illumination module and the waveguide, or between the waveguide and the observer. The phase image generator may include phase shifts for canceling speckle, correcting optical aberrations, and/or compensating interference caused by light rays having different optical path lengths. ## Claims ### Claim 1 An image projector comprising: an illumination module comprising at least one spatially coherent light source; a phase image generator comprising an array of optical phase shifting elements; an electronic image controller in electrical communication with the phase image generator; and a waveguide interposed between the illumination module and an observer and comprising at least two embedded partial reflectors; wherein the phase image generator is interposed between the illumination module and the waveguide, or between the waveguide and the observer, and the phase image generator includes phase shifts for compensating interference caused by light rays having different optical path lengths. ### Claim 2 (depends on 1) The image projector of claim 1 wherein the phase image generator is positioned at an entrance pupil of the waveguide or at an image of the entrance pupil. ### Claim 3 (depends on 1) The image projector of claim 1 wherein the phase image generator generates at least two non-zero diffraction orders which are coupled into the waveguide. ### Claim 4 (depends on 1) The image projector of claim 1 wherein the phase image generator is reflective. ### Claim 5 (depends on 1) The image projector of claim 1 wherein the phase image generator comprises a component selected from a group consisting of a liquid crystal display, a liquid crystal on silicon device, a holographic optical element, and a spatial light modulator. ### Claim 6 (depends on 1) The image projector of claim 1 wherein the phase image generator includes time-varying phase shifts for canceling speckle. ### Claim 7 (depends on 1) The image projector of claim 1 wherein the at least one spatially coherent light source has an intensity which is modulated in time. ### Claim 8 (depends on 1) The image projector of claim 1 wherein the at least one spatially coherent light source comprises a component selected from a group consisting of a laser diode, a diode pumped solid-state laser, and a super-luminescent light emitting diode (SLED). ### Claim 9 (depends on 1) The image projector of claim 1 wherein the illumination module comprises at least two light sources having different wavelengths. ### Claim 10 (depends on 1) The image projector of claim 1 wherein the illumination module further comprises a focusing optical element which comprises a lens, a mirror, or a biconic optical component. ### Claim 11 (depends on 1) The image projector of claim 1 wherein the at least one embedded partial reflector comprises a component selected from a group consisting of a diffraction grating, a diffractive optical element, and a partially reflecting surface. ### Claim 12 (depends on 1) The image projector of claim 1 further comprising an image amplitude modulator. ### Claim 13 (depends on 1) The image projector of claim 1 further comprising an optical beam splitter which comprises a polarizing beam splitter. ### Claim 14 (depends on 1) The image projector of claim 1 further comprising a microlens array and/or a diffuser which is an etendue expander. ### Claim 15 (depends on 1) The image projector of claim 1 further comprising one or more scanning mirrors. ### Claim 16 (depends on 1) The image projector of claim 1 wherein the phase image generator is transmissive. ### Claim 17 (depends on 4) The image projector of claim 4 wherein a positive lens is interposed between the waveguide and the phase image generator or between the phase image generator and the observer. ### Claim 18 (depends on 1) The image projector of claim 1 further comprising an eye tracking camera for tracking a current line of sight of an eye of the observer. ### Claim 19 (depends on 1) The image projector of claim 1 further comprising at least one Volume Bragg Grating.