Phase calibration of spatial light modulators by heterodyne interferometry

In this paper, a method of measuring the phase modulation properties of spatial light modulator (SLM) by heterodyne interferometry is proposed. As a kind of key elements in the advanced optical information processing systems, spatial light modulators is widely used in many important fields, especially used as a dynamic phase modulating device. So, the phase calibration plays an important role in the SLM applications. Compared with the methods based on traditional interferometry, this method measures the phase response directly by taking advantage of the heterodyne mechanism, so it leads to higher accuracy. A heterodyne-interferometer based calibration system making use of acousto-optic frequency-shifters has been designed and realized. Theoretical analysis and experimental results demonstrate the validity of this method.