Optical interferometric apparatus for online real-time thickness inspection

Provided is an optical interferometric apparatus for online real-time thickness inspection. The apparatus comprises a light source, a screen, an image acquisition unit, and an image processing module. The light source is used to generate high coherence point-expanded spherical-wavefront light beam. The screen is arranged in front of the light source, and is used to image interference fringes generated when the high coherence point-expanded spherical-wavefront light beam is radiated to a to-be-tested piece in an oblique angle. The image acquisition unit is arranged in front of the screen, and is used to acquire the interference fringes on the screen and convert the interference fringes to digital images. The image processing module is connected with the image acquisition unit, and is used to analyze the digital images of the interference fringes and perform numerical calculation, so as to obtain full-field thickness distribution of the to-be-tested piece. Thus, the apparatus achieves rapid on-line thickness inspection through the optical path of interference without using optical lens groups and special optical elements. The present invention radiates a high-coherence point-expanded spherical-wavefront light beam in an oblique angle for an instantaneous and wide-area full-field thickness measurement.