US 11,788,834 B2
Method for measuring surface characteristics in optically distorting media
David Stoutamire, Menlo Park, CA (US); and Dennis Hussey, Redwood City, CA (US)
Assigned to Electric Power Research Institute, Inc., Palo Alto, CA (US)
Appl. No. 17/284,470
Filed by Electric Power Research Institute, Inc., Palo Alto, CA (US)
PCT Filed Oct. 12, 2018, PCT No. PCT/US2018/055548
§ 371(c)(1), (2) Date Apr. 11, 2021,
PCT Pub. No. WO2020/076336, PCT Pub. Date Apr. 16, 2020.
Prior Publication US 2021/0389124 A1, Dec. 16, 2021
Int. Cl. G01B 11/25 (2006.01); G06T 7/521 (2017.01)
CPC G01B 11/2527 (2013.01) [G06T 7/521 (2017.01); G06T 2207/30108 (2013.01)] 21 Claims
OG exemplary drawing
 
1. A method for measuring surface characteristics of at least a portion of an object, comprising:
providing at least one light source;
directing light from the at least one light source to generate a first interference pattern on the at least a portion of the object;
capturing at least one first image of the first interference pattern;
shifting the phase of the at least one light source to generate a second interference pattern;
capturing at least one second image of the second interference pattern;
filtering distortion from the first interference pattern and/or the second interference pattern;
extracting a wrapped phase of the at least a portion of the object based on the at least one first image and the at least one second image;
unwrapping the wrapped phase of the at least a portion of the object to generate an unwrapped phase;
identifying a computed depth map distance to the at least a portion of the object based on the unwrapped phase; and
fitting an ideal part to the computed depth map of the at least a portion of the object to measure the surface characteristics;
wherein the object is substantially cylindrical, substantially spherical, or substantially flat on at least one surface, and wherein said measuring surface characteristics includes determining a deviation of a surface characteristic of at least a portion of an object from an ideal surface.