Automated phase-measuring profilometry of 3-D diffuse objects

TLDR

The phase‑shifting interferometric method enables accurate surface profiling even with coarse projected gratings and low‑density image sensors, making it suitable for industrial quality control, biostereometrics, robotics, and computer‑graphics solid modeling. A shearing polarization interferometer projects a sinusoidal grating onto the diffuse surface, an array camera records the deformed grating, and a microcomputer processes the phase distribution to reconstruct the high‑resolution surface profile. The approach attains surface height resolutions better than 10 µm, with performance mainly limited by electronic quantization noise.

Abstract

The high resolution surface profile of a 3-D diffuse object is obtained by measurement of the phase distribution across the image of a projected sinusoidal grating deformed by the surface. A shearing polarization interferometer is used for projection. Deformed grating images are detected by an array camera and processed by a microcomputer. Surface height resolutions of better than 10 μm have been attained, limited essentially by electronic quantization noise. In contrast to direct deformed grating analysis, this method, based on phase-shifting interferometric techniques, is capable of accurate measurement even with coarse projected gratings and low density image sensing arrays. Areas of application include industrial quality control, biostereometrics, robotics, and solid modeling for computer graphics.