A New Method for Testing the Asphere Surface with a Liquid Crystal Spatial Light Modulator

Due to the special properties of asphere lens, the testing of it is more difficult than that of spherical lens. In this paper, the development of a new method using the liquid crystal spatial light modulator (SLM) to measure the accuracy of an aspheric surface is presented. The surface form was measured using a new component as the compensator lens in conjunction to provide an interferogram representing the aspheric form deviation from the nominal. Interferograms are decoded using a spatial-carrier phase shifting technique. The interferometric data is compared to data obtained using a contact stylus profilometer. The system can be mounted over a polishing machine and used for on-line testing of aspheric mirror surfaces.