Adaptive phase control of a phase-only spatial light modulator using the Shack-Hartmann wavefront sensor

Abstract

We present a method to study both static and dynamic phase errors in a phase-only spatial light modulator (SLM) caused by surface irregularities and an imperfect response of each pixel to the applied field. This, in turn, degrades optical reconstruction, particularly in holographic projection applications. The approach uses the Shack-Hartmann wavefront sensor (SHWFS) to measure these errors. A plane wave illuminates the SLM, and the reflected wavefront is measured by the SHWFS and converted into a phase-only computer-generated hologram (CGH). This CGH is displayed on the SLM to compensate for phase errors, which are verified by subsequent wavefront measurements. Experimental results demonstrate the simplicity, robustness to vibration, and real-time capabilities of the SHWFS in contrast to interferometric methods.