US 12,228,392 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)
Filed by Electric Power Research Institute, Inc., Palo Alto, CA (US)
Filed on Oct. 15, 2023, as Appl. No. 18/487,091.
Application 18/487,091 is a continuation of application No. 17/284,470, granted, now 11,788,834, previously published as PCT/US2018/055548, filed on Oct. 12, 2018.
Prior Publication US 2024/0044641 A1, Feb. 8, 2024
This patent is subject to a terminal disclaimer.
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)] 14 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 at least partially submerged in an optically distorting liquid medium of variable and changing indexes of refraction, and
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 thickness change of at least a portion of an object.