Phase response calibration method for liquid crystal spatial light modulators based on low-frequency heterodyne interferometry

Abstract In order to accurately calibrate the liquid crystal spatial light modulator (LC-SLM), a phase response calibration method based on low-frequency heterodyne interferometry is presented, which allows for the full-field phase measurement to be directly carried out by using arbitrary grayscale images from the actual experiment. This method achieves frequency shift via dual acoustic-optic modulators. It enables the pixel-by-pixel detection of time-domain interferometric images to obtain phase distribution. A comparison of the simulated phase against the experimental phase is conducted to calculate the phase-grayscale modulation characteristic curve. The results show that the phase modulation range of the LC-SLM used in the experiment is 0 ∼ 6.2081 rad when the vortex phase is loaded, with the mean error and standard deviation of the modulation curve, measured multiple times, both within 0.013 rad. This outcome indicates the system performs stably. By implementing nonlinear correction with the experimentally calibrated phase response, the nonlinear error of the modulation curve is reduced to 2.68%. Meanwhile, the correlation coefficient with the ideal linear modulation curve is increased to 0.9988, and the root-mean-square error is reduced to 0.1021, effectively improving the linear driving accuracy of the device.