Step-height measurement with a two-wavelength laser diode interferometer using time-sharing sinusoidal phase modulation

摘要

The system we propose uses two separate wavelengths to measure step-height. Two laser diodes alternately modulated with a sinusoidal signal separate a like number of overlapping interference images detected by CCD camera, the phase map being obtained by a modulated LD. In this instance, the 1 μm step-height was accurately detected.