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

A method using fringe projection to describe the three-dimensional profile of a specular object is presented and has steps of: providing a diffraction grating formed by exposing and developing a hologram and having at least two sets of interference fringes; guiding a conjugate of the reference light generated from a conjugate light source to pass through the diffraction grating, in order to generate a real image with a long depth of field, a wide convergent angle, and a sinusoidal distribution light intensity; projecting this real image onto an inspected specular object; using an image capture device to capture the intensity distribution of the real image on the inspected specular object so as to obtain an image signal; and using an image processor to analyze the image signal so as to identify the profile of the inspected specular object.