# US 2021/0278686 A1 · Method and system for fiber scanning projector with angled eyepiece > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0278686 A1 - Document ID: US20210278686A1 - Status: Published application - Kind: A1 - Application number: 17/210,236 - Filed: 2021-03-23 - Published: 2021-09-09 - Earliest claimed: 2018-09-28 - Assignees: Magic Leap, Inc. - Applicants: Magic Leap, Inc. - Inventors: Brian T. Schowengerdt; Mathew D. Watson - Web page: https://patentgrep.com/patent/US20210278686A1 ## CPC - G02B 27/4233: {having a diffractive element [DOE] contributing to a non-imaging application (diffusers having a diffractive element G02B5/0252; filters having a diffractive element G02B5/203; systems for controlling the direction of light having diffractive elements G02B26/0808; scanning systems having diffractive elements G02B26/106; beam shaping systems using diffractive optical elements G02B27/0944; beam splitting or combining systems operating by diffraction G02B27/1086)} - G02B 26/103: {having movable or deformable optical fibres, light guides or waveguides as scanning elements (light guides per se G02B6/00)} - G02B 27/0172: {characterised by optical features} - G02B 27/0179: {Display position adjusting means not related to the information to be displayed} - G02B 27/4205: {having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant} - G02B 27/4227: {in image scanning systems} - G03B 21/142: {Adjusting of projection optics} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - 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) ## Abstract A method of displaying an image to a viewer includes operating a fiber scanning projector to produce a scanned light beam incident on an incoupling diffractive optical element (DOE) coupled to a waveguide. A portion of the light beam is reflected via a reflective back surface of the incoupling DOE. The reflected portion of the scanned light beam is incident on a reflective optical element, which reflects the light beam back to the incoupling DOE. The returning light beam is then diffracted by the incoupling DOE to produce a second pass first diffracted light beam. The second pass first diffracted light beam is propagated within the planar waveguide via total internal reflection (TIR) to an outcoupling DOE, which directs a portion of the second pass first diffracted light beam toward an eye of a viewer to display the image to the user. ## Claims ### Claim 1 A wearable display system comprising: a fiber scanner including: an optical fiber; and a scanning mechanism configured to scan a tip of the optical fiber along an emission trajectory, the emission trajectory defining an optical axis; a collimating optical element positioned along the optical axis and configured to: receive a divergent input light beam emitted from the tip of the optical fiber incident thereon in an on-axis configuration; and produce a collimated light beam; and an eyepiece positioned in front of the tip of the optical fiber, the eyepiece including: a planar waveguide oriented such that a normal of the planar waveguide is tilted at a first angle with respect to the optical axis; and an incoupling diffractive optical element (DOE) coupled to a first lateral region of the planar waveguide that is intercepted by the optical axis, the incoupling DOE configured to: as the divergent input light beam emitted from the tip of the optical fiber is incident on the incoupling DOE on a first pass, produce a first negative first order diffracted light beam that fails total internal reflection (TIR) condition of the planar waveguide; and as the collimated light beam produced by the collimating optical element is incident on the incoupling DOE on a second pass, produce a second negative first order diffracted light beam that meets the TIR condition of the planar waveguide. ### Claim 2 (depends on 1) The wearable display system of claim 1 wherein the eyepiece further includes an outcoupling DOE coupled to a second lateral region of the planar waveguide displaced from the first lateral region, the outcoupling DOE configured to diffract a portion of the second negative first order diffracted light beam out of the planar waveguide toward an eye of a viewer. ### Claim 3 (depends on 1) The wearable display system of claim 1 wherein the collimating optical element comprises a concave mirror. ### Claim 4 (depends on 3) The wearable display system of claim 3 wherein the tip of the optical fiber is positioned on a first side of the eyepiece, and the collimating optical element is positioned on a second side of the eyepiece opposite from the first side. ### Claim 5 (depends on 3) The wearable display system of claim 3 wherein the incoupling DOE is metallized, and wherein the tip of the optical fiber and the collimating optical element are positioned on a same side of the eyepiece. ### Claim 6 (depends on 3) The wearable display system of claim 3 further comprising a mirror positioned along the optical axis on a first side of the eyepiece, wherein the tip of the optical fiber and the collimating optical element are positioned on a second side of the eyepiece opposite from the first side. ### Claim 7 (depends on 1) The wearable display system of claim 1 wherein the emission trajectory of the tip of the optical fiber is forms a two-dimensional convex surface. ### Claim 8 (depends on 1) The wearable display system of claim 1 wherein the emission trajectory of the tip of the optical fiber forms a one-dimensional arc. ### Claim 9 (depends on 1) The wearable display system of claim 1 wherein the tip of the optical fiber comprises an angled facet. ### Claim 10 (depends on 1) The wearable display system of claim 1 wherein the divergent input light beam is imagewise modulated. ### Claim 11 (depends on 1) The wearable display system of claim 1 wherein the optical fiber comprises a non-polarization-maintaining optical fiber, and the divergent input light beam is unpolarized. ### Claim 12 A wearable display system comprising: a fiber scanner including: an optical fiber; and a scanning mechanism configured to scan a tip of the optical fiber along an emission trajectory, the emission trajectory defining an optical axis; an eyepiece positioned in front of the tip of the optical fiber, the eyepiece including: a planar waveguide having a first surface facing the tip of the optical fiber and a second surface opposite the first surface, the planar waveguide oriented such that a normal of the planar waveguide is tilted at a first angle with respect to the optical axis; an incoupling diffractive optical element (DOE) coupled to the second surface of the planar waveguide in a first lateral region that is intercepted by the optical axis, the incoupling DOE comprising a metallized back surface and configured to reflect a first portion of an input light beam emitted from the optical fiber; and an outcoupling DOE coupled to a second lateral region of the planar waveguide and configured to diffract a portion of light propagating in the planar waveguide out of the planar waveguide toward an eye of a viewer; and a collimating optical element configured to: receive the first portion of the input light beam reflected by the incoupling DOE; and collimate and reflect the first portion of the input light beam toward the eyepiece; wherein the incoupling DOE is further configured to diffract a first fraction of the first portion of the input light beam. ### Claim 13 (depends on 12) The wearable display system of claim 12 wherein the first portion of the input light beam is reflected by the incoupling DOE as a zeroth order reflection, and the first fraction of the first portion of the input light beam is diffracted by the incoupling DOE as a negative first order diffraction. ### Claim 14 (depends on 12) The wearable display system of claim 12 wherein the incoupling DOE diffracts the input light beam to form and direct a first pass first diffracted light beam into the planar waveguide that fails to propagate within the planar waveguide via TIR. ### Claim 15 (depends on 14) The wearable display system of claim 14 wherein the first pass first diffracted light beam comprises a positive first order diffraction. ### Claim 16 (depends on 12) The wearable display system of claim 12 wherein: the incoupling DOE diffracts the input light beam to form and direct a first pass second diffracted light beam into the planar waveguide that propagates within the planar waveguide via TIR; and the first pass second diffracted light beam comprises a negative first order diffraction. ### Claim 17 (depends on 12) The wearable display system of claim 12 wherein: the incoupling DOE diffracts the first fraction of the first portion of the input light beam to form and direct a second pass second diffracted light beam into the planar waveguide that fails to propagate within the planar waveguide via TIR; and the second pass second diffracted light beam comprises a positive first order diffraction. ### Claim 18 A wearable display system comprising: a fiber scanner comprising: an optical fiber having a distal end and configured for projection of a light beam from the distal end, an optical axis of the fiber scanner being defined as co-axial with the light beam as projected from the optical fiber when the optical fiber is not deflected; and a scanning mechanism configured to deflect the optical fiber to scan the light beam to produce a scanned light beam that forms an image; an eyepiece comprising: a planar waveguide oriented non-perpendicular to the optical axis of the fiber scanner; and an incoupling diffractive optical element (DOE) coupled to the planar waveguide, the incoupling DOE being configured to diffract the scanned light beam incident on the incoupling DOE on a first pass to produce a first pass first diffracted light beam that fails total internal reflection (TIR) condition of the planar waveguide; and a collimating optical element configured to reflect a portion of the scanned light beam that passes through the incoupling DOE on the first pass to produce a reflected portion of the scanned light beam incident on the incoupling DOE on a second pass, and wherein the incoupling DOE is configured to diffract the reflected portion of the scanned light beam on the second pass to produce a second pass first diffracted light beam that meets the TIR condition of the planar waveguide. ### Claim 19 (depends on 18) The wearable display system of claim 18 wherein the eyepiece further includes an outcoupling DOE coupled to the planar waveguide, the outcoupling DOE being configured to direct at least a portion of the second pass first diffractive light beam out of the planar waveguide toward an eye of a viewer. ### Claim 20 (depends on 18) The wearable display system of claim 18 wherein the collimating optical element is configured so that the reflected portion of the scanned light beam is collimated by the collimating optical element, which comprises a concave mirror.