A grating type dual-image-element demodulation method based on liquid crystal spatial light modulator for spatial phase-shift-interferometry

Abstract

A demodulation method based on liquid crystal spatial light modulator for space domain phase-shift-interferometry is proposed in this paper. In the method, the grating type with dual-image-element mode is used as the phase modulation mode, and the ρ-δ algorithm is proposed with which the interference image is recovered from the modulated image. Finally, the demodulation method is introduced by using the gradient projection algorithm and the arctangent operation. Simulation and experimental results show the effectiveness of the proposed method, in which the image recovery error can be reduced by 1.3 grayscales, and the improvement rate of recovery accuracy is 31.38%. In the 90pixels truncation interface, the effective demodulation pixels are 84 pixels, accounting for 93.33%.

Keywords

• Phase shift interferometry
• Space domain
• Liquid crystal spatial light modulator
• Phase demodulation