Vectorial shearing interferometer with a high resolution phase shifter

Vectorial shearing interferometer has been used to measure small and large non-rotationally symmetrical wavefronts aberrations. This interferometric system encompasses large and differential wavefront displacements using a high accuracy rotation system incorporated in a Mach-Zehnder interferometer. The rotation system is based on the Risley prism arrangement and it is controlled with an electronic servomotor system by means of an auto-tuning algorithm. We present the servo-mechanical system, electronic interface and algorithms to control the performance of the high resolution rotation device that is used to control the wavefront phase shifting