# US 12,113,951 B2 · High-resolution pseudo-random dots projector module for depth sensing > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,113,951 B2 - Document ID: US12113951B2 - Status: Granted - Kind: B2 - Application number: 17/450,351 - Filed: 2021-10-08 - Published: 2023-04-13 - Granted: 2024-10-08 - Earliest claimed: 2021-10-08 - Assignees: Google Inc. - Applicants: Google LLC - Inventors: Xi Chen; Andrew Huibers - Web page: https://patentgrep.com/patent/US12113951B2 ## CPC - G02B 27/18: for optical projection, e.g. combination of mirror and condenser and objective {(photographic, cine and overhead projectors G03B21/00; photographic projection printing G03B27/32; photolithographic projectors G03F7/20; projection television H04N5/74; colour projection television H04N9/31)} - H04N 13/254: in combination with electromagnetic radiation sources for illuminating objects - G01B 11/2513: {with several lines being projected in more than one direction, e.g. grids, patterns} - G01B 11/2527: {with phase change by in-plane movement of the patern} - G01B 11/254: {Projection of a pattern, viewing through a pattern, e.g. moiré} - G01B 11/2545: {with one projection direction and several detection directions, e.g. stereo} - G02B 26/06: for controlling the phase of light (G02B26/08 takes precedence {, measuring optical phase difference G01J9/00}) - G06T 7/521: from laser ranging, e.g. using interferometry; from the projection of structured light - H04N 13/207: using a single two-dimensional [2D] image sensor - H04N 13/271: wherein the generated image signals comprise depth maps or disparity maps - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract A system for projecting dots onto a three-dimensional image is configured to activate multiple pseudo-random dot projectors sequentially. Each pseudo-random dot projector includes an illumination source and a wavefront modulating element (WME) located along an optical axis in a path traversed by radiation produced by the illumination source. The system is configured to form images of dots in the projection plane along the optical axis. The system may also include controlling circuitry configured to perform a sequential projection operation on the plurality of pseudo-random dot projection systems to produce a temporal sequence of images and aggregate and process the temporal sequence of images to produce a high-resolution depth image of the three-dimensional surface. ## Claims ### Claim 1 An apparatus, the apparatus comprising: a plurality of pseudo-random dot projection systems, each of the plurality of pseudo-random dot projection systems including: a respective wavefront modulating element (WME) located along an optical axis in a path traversed by radiation produced by a respective illumination source, the respective WME including a diffractive optical element (DOE), the DOE including features configured to form an image of a respective plurality of dots in a vicinity of a respective projection plane, the respective projection plane being located a distance from the respective WME along the optical axis; and a controlling device, the controlling device including memory; and controlling circuitry coupled to the memory, the controlling circuitry being configured to: perform a projection operation on each of the plurality of pseudo-random dot projection systems according to a specified schedule, the projection operation including, forming an image of the respective plurality of dots on a three-dimensional surface in the vicinity of the respective projection plane to produce a temporal sequence of images; and aggregate the temporal sequence of images to produce a high-resolution depth image of the three-dimensional surface. ### Claim 2 (depends on 1) The apparatus as in claim 1, wherein each of the plurality of pseudo-random dot projection systems further includes a respective focusing optical system located between the respective WME and the respective projection plane along the optical axis. ### Claim 3 (depends on 2) The apparatus as in claim 2, wherein the respective focusing optical system is in optical contact with the respective WME. ### Claim 4 (depends on 1) The apparatus as in claim 1, wherein the respective illumination source emits electromagnetic radiation with a mean wavelength between 800 nm and 1000 nm. ### Claim 5 (depends on 1) The apparatus as in claim 1, wherein the respective illumination source includes an edge-emitting laser diode. ### Claim 6 (depends on 1) The apparatus as in claim 1, wherein each of the plurality of pseudo-random dot projection systems further includes a respective collimating lens, the respective collimating lens being placed along the optical axis between the respective illumination source and the respective WME such that a location of the respective illumination source along the optical axis, the respective collimating lens, and the location of the respective projection plane along the optical axis satisfy a gaussian imaging relationship. ### Claim 7 (depends on 1) The apparatus as in claim 1, wherein the image of the respective plurality of dots formed by each of the plurality of pseudo-random dot projection systems is based on a convolution of a transverse profile of a beam of electromagnetic radiation emitted by the respective illumination source and an impulse response of that pseudo-random dot projection system. ### Claim 8 (depends on 7) The apparatus as in claim 7, wherein the transverse profile of the beam of electromagnetic radiation emitted by the respective illumination source is a gaussian beam having a specified width at the respective illumination source. ### Claim 9 (depends on 8) The apparatus as in claim 8, wherein a local minimum of a width of the gaussian beam along the optical axis occurs at the respective WME. ### Claim 10 (depends on 8) The apparatus as in claim 8, wherein a local minimum of a width of the gaussian beam along the optical axis occurs at the respective projection plane. ### Claim 11 (depends on 1) The apparatus as in claim 1, wherein the respective plurality of dots formed by the respective WME has axial symmetry. ### Claim 12 (depends on 1) The apparatus as in claim 1, wherein the pluralities of dots formed by the WMEs from each of the plurality of pseudo-random dot projection systems are uncorrelated. ### Claim 13 (depends on 1) The apparatus as in claim 1, wherein the pluralities of dots formed by the WMEs from each of the plurality of pseudo-random dot projection systems are the same but translated and rotated with respect to one another. ### Claim 14 A method comprising: performing a projection operation on each of a plurality of pseudo-random dot projection systems according to a specified schedule, the projection operation including forming an image of a respective plurality of dots on a three-dimensional surface in a vicinity of a respective projection plane to produce a temporal sequence of images, the respective plurality of dots formed by features included in a diffractive optical element (DOE) included in a respective wavefront modulating element (WME), the respective WME being located along an optical axis in a path traversed by radiation produced by a respective illumination source, the respective projection plane being located a distance from the respective WME along the optical axis; and aggregating the temporal sequence of images to produce a high-resolution depth image of the three-dimensional surface. ### Claim 15 (depends on 14) The method as in claim 14, wherein each of the plurality of pseudo-random dot projection systems further includes a respective focusing optical system located between the respective WME and the respective projection plane along the optical axis. ### Claim 16 (depends on 14) The method as in claim 14, wherein each of the plurality of pseudo-random dot projection systems further includes a respective collimating lens, the respective collimating lens being placed along the optical axis between the respective illumination source and the respective WME such that a location of the respective illumination source along the optical axis, the respective collimating lens, and the location of the respective projection plane along the optical axis satisfy a gaussian imaging relationship. ### Claim 17 (depends on 14) The method as in claim 14, wherein the image of the respective plurality of dots formed by each of the plurality of pseudo-random dot projection systems is based on a convolution of a transverse profile of a beam of electromagnetic radiation emitted by the respective illumination source and an impulse response of that pseudo-random dot projection system. ### Claim 18 (depends on 17) The method as in claim 17, wherein the transverse profile of the beam of electromagnetic radiation emitted by the respective illumination source is a gaussian beam having a specified width at the respective illumination source. ### Claim 19 (depends on 14) The method as in claim 14, wherein the pluralities of dots formed by the WMEs from each of the plurality of pseudo-random dot projection systems are the same but translated and rotated with respect to one another. ### Claim 20 A computer program product comprising a non-transitory storage medium, the computer program product including code that, when executed by processing circuitry, causes the processing circuitry to perform a method, the method comprising: performing a projection operation on each of a plurality of pseudo-random dot projection systems according to a specified schedule, the projection operation including forming an image of a respective plurality of dots on a three-dimensional surface in a vicinity of a respective projection plane to produce a temporal sequence of images, the respective plurality of dots formed by features included in a diffractive optical element (DOE) included in a respective wavefront modulating element (WME), the respective WME being located along an optical axis in a path traversed by radiation produced by a respective illumination source, the respective projection plane being located a distance from the respective WME along the optical axis; and aggregating the temporal sequence of images to produce a high-resolution depth image of the three-dimensional surface.