# US 2025/0146809 A1 · Light field display metrology > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0146809 A1 - Document ID: US20250146809A1 - Status: Published application - Kind: A1 - Application number: 19/020,531 - Filed: 2025-01-14 - Published: 2025-05-08 - Earliest claimed: 2015-11-04 - Assignees: Magic Leap, Inc. - Applicants: Magic Leap, Inc. - Inventors: Ivan Li Chuen YEOH; Lionel Ernest EDWIN; Samuel A. MILLER - Web page: https://patentgrep.com/patent/US20250146809A1 ## CPC - G01B 11/14: for measuring distance or clearance between spaced objects or spaced apertures (G01B11/26 takes precedence; rangefinders G01C3/00) - G01B 11/22: for measuring depth - G02B 27/01: Head-up displays - G02B 27/017: {Head mounted} - G06F 3/013: {Eye tracking input arrangements (G06F3/015 takes precedence)} - G06T 15/20: Perspective computation - G06T 19/006: {Mixed reality (object pose determination, tracking or camera calibration for mixed reality G06T7/00)} - G09G 3/003: {to produce spatial visual effects} - G09G 3/006: {Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays (testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309)} - G09G 5/02: characterised by the way in which colour is displayed {(details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607)} - H04N 13/144: for flicker reduction - H04N 13/327: Calibration thereof - H04N 13/344: with head-mounted left-right displays - H04N 13/383: for tracking with gaze detection, i.e. detecting the lines of sight of the viewer's eyes - H04N 13/398: Synchronisation thereof; Control thereof - G02B 2027/011: {comprising device for correcting geometrical aberrations, distortion} - G02B 2027/0178: {Eyeglass type (eyeglass details G02C)} - G06F 2203/011: Emotion or mood input determined on the basis of sensed human body parameters such as pulse, heart rate or beat, temperature of skin, facial expressions, iris, voice pitch, brain activity patterns - G06T 3/20: Linear translation of whole images or parts thereof, e.g. panning - G06T 3/40: Scaling of whole images or parts thereof, e.g. expanding or contracting - G06T 3/60: Rotation of whole images or parts thereof - G06T 2207/10012: Stereo images - G06T 2207/10052: Images from lightfield camera - G09G 3/2092: {Details of a display terminals using a flat panel, the details relating to the control arrangement of the display terminal and to the interfaces thereto (suitable for both CRT and flat panel G09G5/003; specific for a CRT G09G1/165)} - G09G 3/3406: {Control of illumination source (illumination devices structurally associated with liquid crystal cells G02F1/1336)} - G09G 2320/0233: Improving the luminance or brightness uniformity across the screen - G09G 2320/0242: Compensation of deficiencies in the appearance of colours - G09G 2320/0276: for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction - G09G 2320/028: by changing the viewing angle properties, e.g. widening the viewing angle, adapting the viewing angle to the view direction - G09G 2320/029: by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel - G09G 2320/0626: for control of overall brightness - G09G 2320/0666: for control of colour parameters, e.g. colour temperature - G09G 2320/0673: for control of gamma adjustment, e.g. selecting another gamma curve - G09G 2320/0693: Calibration of display systems - G09G 2340/0464: Positioning - G09G 2360/16: Calculation or use of calculated indices related to luminance levels in display data - H04N 13/395: with depth sampling, i.e. the volume being constructed from a stack or sequence of two-dimensional [2D] image planes - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL - G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Examples of a light field metrology system for use with a display are disclosed. The light field metrology may capture images of a projected light field, and determine focus depths or lateral focus positions for various regions of the light field using the captured images. The determined focus depths or lateral positions may then be compared with intended focus depths or lateral positions, to quantify the imperfections of the display. Based on the measured imperfections, an appropriate error correction may be performed on the light field to correct for the measured imperfections. The display can be an optical display element in a head mounted display, for example, an optical display element capable of generating multiple depth planes or a light field display. ## Claims ### Claim 1 An optical metrology system for image correction of a display, the system comprising: at least one camera configured to capture one or more images of virtual content being projected by the display, wherein the display is configured to present the virtual content at a plurality of depth planes; and a hardware processor programmed with executable instructions to: access the one or more images captured by the at least one camera; determine, based at least partly on the one or more images, at least one value indicating a luminance of each of a plurality of points on the display; calculate, based at least partly on said determined values, at least one correction for the display, wherein the at least one correction includes a luminance flattening correction; and store the at least one correction in memory that is associated with the display, wherein the display comprises a plurality of display layers, and wherein the luminance flattening correction is calculated for each of the display layers. ### Claim 2 (depends on 1) The optical metrology system of claim 1, wherein at least one of the display layers comprises at least one of: (i) a depth layer configured to present at least a portion of the virtual content at one of the plurality of depth planes, or (ii) a color layer configured to present at least a portion of the virtual content formed of light that is within a particular range of wavelengths. ### Claim 3 (depends on 1) The optical metrology system of claim 1, wherein different luminance flattening corrections are calculated for at least two of the display layers. ### Claim 4 (depends on 3) The optical metrology system of claim 3, wherein the at least two of the display layers are different color layers, and wherein the at least one correction further includes a chromatic balancing correction that is determined to correct for chromatic non-uniformity caused by applying the different luminance flattening corrections for the at least two of the display layers. ### Claim 5 (depends on 1) The optical metrology system of claim 1, wherein each of the display layers comprises one or more waveguides. ### Claim 6 (depends on 1) The optical metrology system of claim 1, wherein to calculate the luminance flattening correction, the hardware processor is programmed to: determine a threshold value; and calculate, for each of the values indicating the luminance greater than the threshold value, an amount to lower the respective value to the threshold value. ### Claim 7 (depends on 1) The optical metrology system of claim 1, wherein the luminance flattening correction is calculated so that each value reduces the luminance of the corresponding point to the minimum luminance among the points. ### Claim 8 (depends on 1) The optical metrology system of claim 1, wherein the at least one camera comprises a light field camera or a digital camera having a small depth of focus. ### Claim 9 (depends on 1) The optical metrology system of claim 1, wherein the virtual content comprises at least one of a checkerboard pattern, a geometric pattern, or a stochastic pattern. ### Claim 10 A method performed by an optical metrology system for image correction of a display, the method comprising: accessing one or more images captured by at least one camera configured to capture one or more images of virtual content being projected by the display, wherein the display is configured to present the virtual content at a plurality of depth planes; determining, based at least partly on the one or more images, at least one value indicating a luminance of each of a plurality of points on the display; calculating, based at least partly on said determined values, at least one correction for the display, wherein the at least one correction includes a luminance flattening correction; and storing the at least one correction in memory that is associated with the display, wherein the display comprises a plurality of display layers, and wherein the luminance flattening correction is calculated for each of the display layers. ### Claim 11 (depends on 10) The method of claim 10, wherein at least one of the display layers comprises at least one of: (i) a depth layer configured to present at least a portion of the virtual content at one of the plurality of depth planes, or (ii) a color layer configured to present at least a portion of the virtual content formed of light that is within a particular range of wavelengths. ### Claim 12 (depends on 10) The method of claim 10, wherein different luminance flattening corrections are calculated for at least two of the display layers. ### Claim 13 (depends on 12) The method of claim 12, wherein the at least two of the display layers are different color layers, and wherein the at least one correction further includes a chromatic balancing correction that is determined to correct for chromatic non-uniformity caused by applying the different luminance flattening corrections for the at least two of the display layers. ### Claim 14 (depends on 10) The method of claim 10, wherein each of the display layers comprises one or more waveguides. ### Claim 15 (depends on 10) The method of claim 10, wherein to calculate the luminance flattening correction, the hardware processor is programmed to: determine a threshold value; and calculate, for each of the values indicating the luminance greater than the threshold value, an amount to lower the respective value to the threshold value. ### Claim 16 (depends on 10) The method of claim 10, wherein the luminance flattening correction is calculated so that each value reduces the luminance of the corresponding point to the minimum luminance among the points. ### Claim 17 (depends on 10) The method of claim 10, wherein the at least one camera comprises a light field camera or a digital camera having a small depth of focus. ### Claim 18 (depends on 10) The method of claim 10, wherein the virtual content comprises at least one of a checkerboard pattern, a geometric pattern, or a stochastic pattern.