摘要

Modulation measurement profilometry can achieve the reconstruction of a tested object with complex or step-like surface. The technology applying coaxial and coimage plane optical systems in which the projection axis coincides with the observation axis can effectively avoid the defects of shadow, shade, and phase discontinuity. All of these weaknesses are largely present in optical three-dimensional sensing based on trigonometric measurement principle. However, in the practical application, the captured fringe patterns are always inevitably influenced by noise, which will directly affect the measurement accuracy. As a well-known and remarkable time-frequency analysis tool, the wavelet transform (WT) method has a strong noise immunity and is suitable to analyze nonstationary signals. Comparisons between the WT method and the Fourier transform method are made not only by computer simulations appearing robust within various types of noise but also the practical experiment. It shows that the WT method is helpful in the enhancement of measurement accuracy. Additionally, experiment further verifies its strong antinoise ability.