Modeling of effect of LC SLM phase fluctuations on kinoforms optical reconstruction quality

Abstract

Phase-only liquid crystal (LC) spatial light modulators (SLM) are actively used in various applications. However, majority of scientific applications require stable phase modulation which might be hard to achieve with commercially available SLM due to its consumer origin. The use of digital voltage addressing scheme leads to phase temporal fluctuations, which results in lower diffraction efficiency and reconstruction quality of displayed diffractive optical elements (DOE). It is often preferable to know effect of these fluctuations on DOE reconstruction quality before SLM is implemented into experimental setup. It is especially important in case of multi-level phaseonly DOE such as kinoforms. Therefore we report results of modeling of effect of phase fluctuations of LC SLM “HoloEye PLUTO VIS” on kinoforms optical reconstruction quality. Modeling was conducted in the following way. First dependency of LC SLM phase shift on addressed signal level and time from frame start was measured for all signal values (0-255) with temporal resolution of 0.5 ms in time period of one frame. Then numerical simulation of effect of SLM phase fluctuations on kinoforms reconstruction quality was performed. Based on measured dependency, for each time delay new distorted kinoform was generated and then numerically reconstructed. Averaged reconstructed image corresponds to optically reconstructed one with registration time exceeding time period of one frame (16.7 ms), while individual images correspond to momentary optical reconstruction with registration time less than 1 ms. Quality degradation of modeled optical reconstruction of several test kinoforms was analyzed. Comparison of kinoforms optical reconstruction with SLM and numerically simulated reconstruction was conducted.