Calibration of phase-only liquid-crystal spatial light modulators by diffractogram analysis

Abstract

Phase-only spatial light modulator (SLM) is a key device for light manipulation. It is critical to calibrate the grayscale-phase response to the driving voltage of SLM, namely the look-up table (LUT), before use. The conventional calibration methods, which rely on interference, diffraction, or polarization to extract the phase, require extra optical devices and are sensitive to mechanical vibration, air turbulence, and systematic aberrations. To overcome these shortcomings, here we develop a novel method, which is based on the diffractogram analysis. By analyzing the intensity distribution of the diffractogram as a function of the specific SLM hologram, we identify both the global and the localized LUTs of SLM at high accuracy. Compared with the other ones, our method allows in-situ SLM calibration and is more tolerant to the exogenous factors.