Vertical scanning profilometry using double-exposure camera and two short-coherent-light sources of different wavelengths

Abstract

We propose a new vertical-scanning profilometry which has potentiality of realizing high-speed measurement. The proposed profilometry measures 3-D shape by use of phase-shifting techniques with a large phase shift 2n π + π/2. With such large shifts, 2 pai phase ambiguities normally suffer precision measurements of phases. Therefore, the profilometry was equipped with two short-coherent-light sources of different wavelengths and a double-exposure camera, and measures the phases of two different wavelengths at nearly the same optical path difference. From the phases and a vertical-scanning step height, 3-D profile is calculated with nanometer precision.