Multi-region phase calibration of liquid crystal SLM for holographic display.

The liquid crystal spatial light modulator (SLM) is able to provide flexible wavefront control, whereas the initial phase and its response distortions will heavily influence the modulation accuracy. The currently existing calibration methods are tedious and time consuming. A novel multi-region calibration method for minimizing those distortions is proposed. The entire panel is divided into several local regions based on the similarity of phase response characteristic. The nonlinear phase response and static phase distortion of each local region are calibrated in the iterative division procedure. The calibration method is theoretically analyzed and experimentally verified. For the Jasper 4 K SLM panel, when five local regions are built, the root mean error of linear phase shifts is reduced to 0.1 rad and the compensation accuracy of the static phase distortion reaches 0.24 wavelength. The calibrated SLM is applied for the color holographic display and the results show that the reconstructed image quality is improved significantly. The proposed method is simpler and faster because of the reasonable regional division and lower calibration complexity. It could be used for the calibration of various phase only or complex modulators with high space bandwidth product in the future.