Flexible high-resolution wavefront sensor using a double-frequency two-dimensional acousto-optic modulator

Abstract

A versatile wavefront sensor is described, using a two-dimensional acousto-optic modulator (AOM) driven with double radio frequencies in both the orthogonal directions. Inserted in the spectral plane in a 4-f system, the AOM acts like a moving double-frequency crossed grating. The proposed wavefront sensor inherits the advantages of a double-frequency grating lateral shearing interferometer in the aspects of high-resolution slope estimations and structure compactness. The sensor naturally performs as a heterodyne detection system, thanks to the inherent property of traveling waves in acousto-optic modulators. Variable shear can be acquired conveniently by electronically adjusting the driving frequencies, with the optimal performance achieved under different circumstances involving parameters such as accuracy, dynamic range, and signal-to-noise ratio. Beyond the proposed concept, theory analysis is presented in detail, and simulations are carried out to demonstrate the principle and validation of the proposed wavefront sensor.