# US 10,871,654 B2 · Compact head-mounted display system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,871,654 B2 - Document ID: US10871654B2 - Status: Granted - Kind: B2 - Application number: 16/717,716 - Filed: 2019-12-17 - Published: 2020-04-23 - Granted: 2020-12-22 - Earliest claimed: 2016-02-18 - Assignees: Oorym Optics Ltd. - Applicants: Oorym Optics Ltd. - Inventors: Yaakov Amitai; Nadav Amitai - Web page: https://patentgrep.com/patent/US10871654B2 ## CPC - G02B 27/0172: {characterised by optical features} - G02B 6/00: Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings - G02B 6/0031: {Reflecting element, sheet or layer} - G02B 6/0053: {Prismatic sheet or layer; Brightness enhancement element, sheet or layer} - G02B 6/0055: {Reflecting element, sheet or layer} - G02B 6/0065: {Manufacturing aspects; Material aspects} - G02B 2027/0123: {comprising devices increasing the field of view} - G02B 2027/0125: {Field-of-view increase by wavefront division} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract There is provided an optical device, including a light-transmitting substrate having at least two parallel major surfaces, edges and an output aperture, an optical element for coupling light waves into the substrate to effect total internal reflection, at least one first reflecting surface having at least one active side, located between the two major surfaces of the light-transmitting substrate for coupling light waves out of the substrate, and a partially reflecting element positioned outside of the substrate, wherein light waves coupled out from the substrate through the output aperture, are partially coupled back into the substrate by the partially reflecting element. ## Claims ### Claim 1 An optical device, comprising: a light-transmitting substrate having at least two parallel major surfaces, edges and an output aperture; an optical element for coupling light waves into the substrate to effect total internal reflection; at least one first reflecting surface having at least one active side, located between the two major surfaces of the light-transmitting substrate, for coupling light waves out of the substrate, and a partially reflecting element positioned outside of the substrate, wherein light waves coupled out from the substrate through the output aperture, are partially coupled back into the substrate by the partially reflecting element. ### Claim 2 (depends on 1) The optical device according to claim 1, wherein the light waves trapped inside the substrate are plane light waves. ### Claim 3 (depends on 1) The optical device according to claim 1, wherein the optical element for coupling light waves into the substrate, is a second reflecting surface carried by a slanted edge of the substrate and located parallel to the reflecting surface. ### Claim 4 (depends on 3) The optical device according to claim 3, further comprising a third reflecting surface carried inside the substrate and parallel to the reflecting surface, wherein light waves partially reflected by the partially reflecting element are further reflected by the third reflecting surface before being coupled again into the substrate. ### Claim 5 (depends on 1) The optical device according to claim 1, wherein the light waves partially reflected by the partially reflecting element, are further reflected by the first reflecting surface before being coupled again into the substrate. ### Claim 6 (depends on 5) The optical device according to claim 5, wherein two light rays spaced-apart from each other emanate from a single plane light wave, coupled into the substrate by the second reflecting surface, are coupled-out from the substrate by the first reflecting surface adjacent to each other. ### Claim 7 (depends on 1) The optical device according to claim 1, wherein the partially reflecting element is at least one partially reflecting surface. ### Claim 8 (depends on 1) The optical device according to claim 1, wherein the partially reflecting element is an array of reflecting surfaces spaced-apart from each other. ### Claim 9 (depends on 1) The optical device according to claim 1, wherein the partially reflecting element is embedded inside a transparent prism having at least two external surfaces. ### Claim 10 (depends on 9) The optical device according to claim 9, wherein one of the external surfaces of the prism is optically attached to one of the major surfaces of the substrate defining an interface plane, light waves coupled out of the substrate by the reflecting surface substantially pass through the interface plane without any significant reflectance, and light waves coupled inside the substrate are substantially reflected by the interface plane without any significant transmittance. ### Claim 11 (depends on 10) The optical device according to claim 10, wherein the prism is cemented by an optical adhesive to one of the major surfaces of the substrate at the interface plane, the substrate and the optical adhesive having refractive indices and the refractive index of the optical adhesive is substantially lower than the refractive index of the substrate. ### Claim 12 (depends on 1) The optical device according to claim 1, wherein light waves coupled out from the substrate through the output aperture partially pass through the partially reflecting element to reach a viewer's eye. ### Claim 13 (depends on 1) The optical device according to claim 1, wherein the first reflecting surface is a polarization-sensitive reflecting surface. ### Claim 14 (depends on 1) The optical device according to claim 1, wherein an angular sensitive reflecting coating is applied to the first reflecting surface, the first reflecting surface is substantially reflective for light waves coupled out from the substrate by the reflecting surface and for light waves coupled back into the substrate by the partially reflecting element, and the first reflecting surface is substantially transparent to light waves passing through the substrate into a viewer's eye. ### Claim 15 (depends on 1) The optical device according to claim 1, wherein the partially reflecting element comprises at least one polarization-sensitive reflecting surface. ### Claim 16 (depends on 15) The optical device according to claim 15, wherein the polarization-sensitive partially reflecting surface is reflective for one polarization and substantially transparent to an orthogonal polarization.