Study Of Noncontact Online Testing Technology For Spherical Lenses With Twyman-Green Interferometer

At present, the demand for highly precise optical part has increased sharply, so a relevant optical test technology is needed to guarantee its quality. Under such circumstance, the research group has developed a interferometric system of noncontact without precision guider of Twyman-Green which is fit to test the curvature deviation and surface form deviation in workshop.The paper mainly focuses on the image acquisition and processing system of the interferometer produced by the research group. Firstly, the principle of interference and Twyman-Green interferometer is introduced in the paper. Next the measurement principle and the optical system of the interferometer are analyzed in details. Then the corresponding parts are looked for according to the image acquisition system and processing system. In order to decrease the error of subjective factors, the processing program is written with Matlab software to deal with the interference image obtained by the experimental interferometer automatically. The whole process of image processing is analyzed in details and the better method is chose for the system. Finally the principle and computer method of Zernike polynomial are introduced. The interference fringe obtained by the experimental prototype is fitted with Zernike polynomial and the surface deviation information PV and RMS is calculated in Matlab. The analysis shows that the error of wavefront fitting is distinct, so the analysis needs improving.In the end, the study work has been summarized, and some other modified methods of image processing and polynomial fitting are also given for further working.