3-D Surface Profile Measurement Using An Acousto-optic Tunable Filter Based Spectral Phase Shifting Technique

An acousto-optic tunable filter based 3-D micro surface profile measurement using an equally spaced 5 spectral phase shifting is described. The 5-bucket spectral phase shifting method is compared with a Fourier-transform method in tire spectral domain. It can provide a. fast measurement capability while maintaining high accuracy since it needs only 5 pieces of spectrally please shifted imaging data and a simple calculation in comparison with the Fourier transform method that requires fill wavelength scanning data and relatively complicated computation. The 3-D profile data. of micro objects can be obtained in a few seconds with an accuracy of (similar to) 10 nm. The 3-D profile method also has an inherent benefit in terms of being speckle-free in measuring diffuse micro objects by employing an incoherent light; source. Those simplicity and practical applicability is expected to have diverse applications in 3-D micro profilometry such as semiconductors and micro-biology.