# US 2020/0396362 A1 · Imaging device based on lens assembly with embedded filter > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0396362 A1 - Document ID: US20200396362A1 - Status: Published application - Kind: A1 - Application number: 17/004,323 - Filed: 2020-08-27 - Published: 2020-12-17 - Earliest claimed: 2017-09-01 - Assignees: Facebook Technologies, LLC - Applicants: Facebook Technologies, LLC - Inventors: Andrew Matthew Bardagjy; Joseph Duggan; Cina Hazegh; Fei Liu; Mark Timothy Sullivan; Simon Morris Shand Weiss - Web page: https://patentgrep.com/patent/US20200396362A1 ## CPC - H04N 5/2226: {Determination of depth image, e.g. for foreground/background separation (determining depth by image analysis in general G06T7/50; segmentation by image analysis in general G06T7/10)} - H04N 23/75: by influencing optical camera components - G02B 5/281: {designed for the infrared light} - G02B 27/0172: {characterised by optical features} - G02B 27/425: {in illumination systems (mask illumination systems in photolithographic systems G03F7/70158)} - G06T 7/521: from laser ranging, e.g. using interferometry; from the projection of structured light - H04N 23/55: Optical parts specially adapted for electronic image sensors; Mounting thereof - H04N 23/56: provided with illuminating means - H04N 23/71: Circuitry for evaluating the brightness variation - H04N 23/74: by influencing the scene brightness using illuminating means - G02B 2027/0138: {comprising image capture systems, e.g. camera} - G02B 2027/014: {comprising information/image processing systems} - G06T 7/55: from multiple images - G06T 2207/10028: Range image; Depth image; 3D point clouds - G06T 2207/10152: Varying illumination - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract An imaging device for imaging of a local area surrounding the imaging device. The imaging device includes a lens assembly, a filtering element and a detector. The lens assembly is configured to receive light from a local area surrounding the imaging device and to direct at least a portion of the received light to the detector. The filtering element is placed in the imaging device within the lens assembly such that light is incident at a surface of the filtering element within a range of angles determined by a design range of angles at which the filtering element is designed to filter light. The detector is configured to capture image(s) of the local area including the filtered light. The imaging device can be integrated into a depth camera assembly for determining depth information of object(s) in the local area based on the captured image(s). ## Claims ### Claim 1 An imaging device comprising: a lens assembly configured to generate collimated light using light received from a local area, the collimated light including reflected illumination light and ambient light; a filtering element embedded within the imaging device at a location where light rays of the collimated light are incident to a surface of the filtering element within a range of angles around a center angle of incidence for which the filtering element is designed to reduce an intensity of incident light to generate filtered light substantially without the ambient light; and a detector configured to capture one or more images of the local area including the filtered light. ### Claim 2 (depends on 1) The imaging device of claim 1, wherein the filtering element is configured to: block a portion of the collimated light having one or more wavelengths outside a defined band; and propagate other portion of the collimated light having one or more other wavelengths within the defined band to generate the filtered light. ### Claim 3 (depends on 1) The imaging device of claim 1, wherein the detector is further configured to: capture the one or more images by capturing, at each pixel of the detector, a light signal related to the filtered light for each time instant of one or more time instants. ### Claim 4 (depends on 3) The imaging device of claim 3, further comprising: a controller coupled to the detector configured to determine depth information for the local area based on one or more light signals related to the filtered light captured at each pixel of the detector during the one or more time instants. ### Claim 5 (depends on 1) The imaging device of claim 1, wherein the center angle is an angle between an axis perpendicular to the surface of the filtering element and a center axis of a cone of light whose apex is at the surface of the filtering element. ### Claim 6 (depends on 1) The imaging device of claim 1, wherein an amount of collimation of the collimated light is inversely proportional to a size of the range of angles. ### Claim 7 (depends on 1) The imaging device of claim 1, wherein the surface of the filtering element is coated to reflect a portion of the collimated light having one or more wavelengths outside a defined band. ### Claim 8 (depends on 1) The imaging device of claim 1, wherein the surface of the filtering element is coated to propagate a portion of the collimated light having one or more wavelengths within a defined band to generate the filtered light. ### Claim 9 (depends on 1) The imaging device of claim 1, wherein the filtering element is embedded within the lens assembly. ### Claim 10 (depends on 1) The imaging device of claim 1, wherein the illumination light is temporally modulated. ### Claim 11 (depends on 1) The imaging device of claim 1, wherein the illumination light includes structured light. ### Claim 12 (depends on 1) The imaging device of claim 1, wherein the imaging device is a component of a depth camera assembly. ### Claim 13 (depends on 1) The imaging device of claim 1, wherein the imaging device is a component of a head-mounted display. ### Claim 14 A method comprising: generating collimated light using light received from a local area, the collimated light including reflected illumination light and ambient light; generating filtered light substantially without the ambient light using a filtering element embedded within an imaging device at a location where light rays of the collimated light are incident to a surface of the filtering element within a range of angles around a center angle of incidence for which the filtering element is designed to reduce an intensity of incident light; and capturing one or more images of the local area including the filtered light. ### Claim 15 (depends on 14) The method of claim 14, further comprising: blocking a portion of the collimated light having one or more wavelengths outside a defined band; and propagating other portion of the collimated light having one or more other wavelengths within the defined band to generate the filtered light. ### Claim 16 (depends on 14) The method of claim 14, further comprising: capturing the one or more images by capturing, at each pixel of a detector, a light signal related to the filtered light for each time instant of one or more time instants; and determining depth information for the local area based on one or more light signals related to the filtered light captured at each pixel of the detector during the one or more time instants. ### Claim 17 (depends on 14) The method of claim 14, wherein the center angle is an angle between an axis perpendicular to the surface of the filtering element and a center axis of a cone of light whose apex is at the surface of the filtering element. ### Claim 18 (depends on 14) The method of claim 14, wherein an amount of collimation of the collimated light is inversely proportional to a size of the range of angles. ### Claim 19 A head-mounted display (HMD) comprising: a display configured to emit image light; a light generator configured to illuminate a local area with illumination light in accordance with emission instructions; a lens assembly configured to generate collimated light using light received from a local area, the collimated light including reflected illumination light and ambient light; a filtering element embedded within the imaging device at a location where light rays of the collimated light are incident to a surface of the filtering element within a range of angles around a center angle of incidence for which the filtering element is designed to reduce an intensity of incident light to generate filtered light substantially without the ambient light; and a detector configured to capture one or more images of the local area including the filtered light; a controller configured to: generate the emission instructions, provide the emission instructions to the light generator, and determine depth information for the local area using the captured one or more images; and an optical assembly configured to direct the image light to an eye-box of the HMD corresponding to a location of a user's eye, the image light comprising the determined depth information. ### Claim 20 (depends on 19) The HMD of claim 19, wherein the surface of the filtering element is coated to reflect a portion of the collimated light having one or more wavelengths outside a defined band and to propagate another portion of the collimated light having one or more other wavelengths within the defined band to generate the filtered light.