Abstract
A new method for profile measurement using phase-shifting technique is proposed and verified by experiments. The method realizes the measurement by projecting an interferometric fringe pattern as a grating pattern on the object surface and by observing the deformed fringe pattern at the direction different from the projection. The fringe pattern is shifted in four steps by means of a mirror mounted on a piezoelectric translator. Path difference at each point on the object surface is calculated precisely from the four intensity data. From the path difference data, we can calculate the object profile. This technique needs no fine fringe pattern to improve lateral resolving power as it gives height distribution at all the picture elements over the object image. Furthermore, the technique has the advantage that it can measure the object with spatially varying reflectivity. This paper also estimates the measuring errors caused by A/D converter.
