Patent ID: 9384540
Filing Date: 2016-07-05
CPC Classification: G01B,G01N,G06T

Claim Text:
1. A method for measuring phase shift to detect irregularities of a surface, said method is implemented with a camera, a computing device coupled to or within the camera, a light source, a surface disposed opposite the light source, a semi-reflective reference plane disposed between the light source and the surface, and a beam splitter disposed between the light source and the reference plane, wherein the light source emits a light beam comprising a first portion and a second portion, wherein the first portion is reflected by the reference plane and the second portion is transmitted through the reference plane and reflected by the surface, wherein the beam splitter directs the reflected first portion and the reflected second portion to the camera, said method comprising the steps of: generating a first image by exposing the camera to the first portion and the second portion of the light beam while translating the reference plane along a distance between the surface and the beam splitter at a first phase sweep rate; generating a second image by exposing the camera to the first portion and the second portion of the light beam while translating the reference plane along the distance at a second phase sweep rate; generating a third image by exposing the camera to the first portion and the second portion of the light beam while translating the reference plane along the distance at a third phase sweep rate; generating, by the computing device, a first Fourier transform image and a second Fourier transform image based on the first image, the second image, and the third image; and generating, by the computing device, a phase image based on the first Fourier transform image and the second Fourier transform image.