Phase Calibration of Liquid-Crystal-Based Spatial Light Modulators Using the Spatial Structure of Focused Optical Fields

Abstract

We present an in situ microscopic technique to calibrate phase-only liquid-crystal-based spatial light modulators LC SLM). The technique relies on the spatial structure of focused fields that are commonly encountered in optical microscopy. To retrieve the phase response curve of the LC SLM, we modulate the phase of one half of the incident beam, record the resulting variations of the focused fields at the focal plane of the microscope objective, and perform a correlation of those variations in the corresponding experimental and theoretical intensity distributions of the focused fields. We establish the validity of the technique by comparing its performance to the well-known two-beam interference technique for calibrating a phase-only LC SLM. Our technique is general, robust, and directly applicable to any microscopy set up that utilizes a LC SLM in the excitation path.