Compact optical encoder using modulated-pitch phase grating: suppressionof harmonic noise and contrast change,

摘要

Abstract: In this paper, we investigate the combination of two gratings for a compact optical displacement encoder. The modulated pitch gratings are considered to obtain the sinusoidal signal as a function of displacement. In addition, the phase grating with the pitch modulation is examined to suppress the contrast change of the encoder signal as a function of the gap between the index and main scales. By these investigations, we find some combinations of gratings to satisfy the above requirements. !4