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

A demodulation method based on liquid crystal spatial light modulator for space domain phase-shiftinterferometry 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 rho-delta 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%.

Automated summary

This paper proposes a demodulation method based on liquid crystal spatial light modulator for space domain phase-shift interferometry. The method uses the grating type with dual-image-element mode as the phase modulation mode, and introduces the rho-delta algorithm to recover the interference image from the modulated image. Finally, the demodulation method is implemented using the gradient projection algorithm and the arctangent operation. Simulation and experimental results show the effectiveness of the proposed method, with a reduction of 1.3 grayscales in image recovery error and a 31.38% improvement rate in recovery accuracy. In the 90-pixel truncation interface, there are 84 effective demodulation pixels, accounting for 93.33% of the total pixels.