Research On Optical Surface Testing With Interferometers

Testing technique used interferometer is based on light interference principle. Compared to the general optical testing technology, measurement with interferometer has a higher sensitivity and accuracy, and it will not produce additional damage and error to the measured surface. In the shearing interference method the measured wavefront will be interfered with another wavefront which is a small translation of the measured wavefront itself. This method does not need standard reference wavefront, and the sensitivity is adjustable. So it is particularly propitious to measure aspherics with large asphericity, and this method has a very good application prospect. Many shear interferometers are used common optical path system that can resist the impact of external disturbances, and this system has a low demand to the coherence of light source and the stability of interferometry devices platform.This paper summarized the testing technique of domestic and overseasfor to optical surface with interferometer. Based on the extensive research of the measurement method to large optical component of domestic and foreign, the research status of the large optical component testing method was reviewed, and common tesing method of aspheric was emphatically analyzed and studied. The important significance of test to large optical component was expounded To the existed problem, the major research contents of this paper was put forward.Theory and principle of optical surface testing technique with shearing interferometer system were studied. Measurement principle, characteristics and system structure of the traditional shearing interferometry, Zygo interferometer and EFL M50 shear interferometer were analyzed and studied detailedly. Interferogram processing and phase analysis of the measurement with shearing interferometer were studied.Measurement experiment and method to optical surface were studied. The measurements to a aluminum planar turned by diamond with PGI and EFL M50 interferometer were conducted respectively. By contrast and analysis with the measuring results. The detection used EFL M50 shear interferometer showed good effects Finally, the error of measurement to optical surface profile was analyzed. The advantages and disadvantages of testing to large optical surface with PGI and EFL M50 shearing interferometer were evaluated.