Calibration Method of Liquid-Crystal Spatial Light Modulator Based on a 1-D Phase Retrieval Algorithm

Abstract

Liquid-crystal spatial light modulator (LC-SLM) has been widely applied as a programmable digital device. However, the LC-SLM can only manipulate on light fields accurately under designated wavelengths since, when being uploaded a specific grayscale image onto it, the phase retardance offered by the LC-SLM is relevant to the wavelength of the incident light. This means that the calibration of LC-SLM is indispensable once the working wavelength changes. In this paper, based on a phase retrieval algorithm, a novel phase calibration method with high efficiency and accuracy is proposed for scaling LC-SLM. In the method, a 1-D phase retrieval algorithm for recovering the phase of a 1-D light field distribution is used to measure the voltage-phase characteristic curve of LC-SLM, where the gradient descent algorithm with a Root Mean Square propagation is introduced to obtain the phase. Simulations and experiments show that this method is stable and has the ability of anti-noise on some conditions and can eliminate the influence caused by crosstalk between pixels on the calibration. Compared with the traditional diffraction-based method, our method improves the calibration error up to 30% under the same experimental conditions.