US Patent No. 9,739,602

METHOD FOR MEASURING THREE-DIMENSIONAL PROFILE OF SPECULAR OBJECT BY FRINGE PROJECTION


Patent No. 9,739,602
Issue Date August 22, 2017
Title Method For Measuring Three-dimensional Profile Of Specular Object By Fringe Projection
Inventorship Wei-Hung Su, Kaohsiung (TW)
Bo-Chin Huang, Kaohsiung (TW)
Assignee NATIONAL SUN YAT-SEN UNIVERSITY, Kaohsiung (TW)

Claim of US Patent No. 9,739,602

1. A method for measuring a specular object by fringe projection, comprising steps of:
(S1) using a diffusion plane to receive a beam which has a fringe data, and generating a diffusion beam according to a diffusion
effect of the diffusion plane;

(S2) using a hologram to receive a reference beam and the diffusion beam, wherein the reference beam interferes with the diffusion
beam on the hologram to generate a set of interfere fringes exposed on the hologram;

(S3) moving the diffusion plane to add a predetermined distance between the hologram and the diffusion plate;
(S4) repeating the steps (S1) to (S3) at least one time to use at least two set of diffusion beams with different depths to
generate at least two sets of interfere fringes on the hologram;

(S5) developing and fixing the at least two sets of interfere fringes on the hologram to form a diffraction grating;
(S6) arranging the diffraction grating with an image processor, a conjugate light source and an image capture device to form
a fringe projection profilometry;

(S7) providing a conjugate of reference light generated from the conjugate light source to pass through the diffraction grating,
so as to reconstruct a real image, wherein the real image is a fringe image which has a sinusoidal distribution light intensity;
and then projecting the fringe image onto an inspected specular object;

(S8) using the image capture device to capture a diffusion image on the inspected specular object to obtain an image signal;
and

(S9) using the image processor to analyze the image signal, so as to identify the profile of the inspected specular object.