Study Of Optical Surface Deviation Detection Technology Based On Wavefront Fitting

The interferometer, for its high measuring accuracy, it plays an extremely important role in the modern high-tech. As the photoelectric products makes rapidly increasing demand for optical components, at the same time, which imposes higher and more strict requirements on the quality of optical elments, all of these come up with higher challenges to the automatic testing quality and speed of interferometer. Nowadays, many imported interferometers with fast detection efficiency and high detection accuracy, duo to its expensive prices, which makes these interferometers only as a terminal testing equipments. Optical cold processing enterprises urgently need a kind of non-contact online testing interference instrumentation that should be self-developed and own a relatively higher degree of automation, the laboratory independently developed a kind of non-contact online spherical interferometer based on this point.The main objective of this paper is to develope a kind of calculation method that could automatically detect lens surface shape deviation according to the interference pattern and apply this method to the interferometer developed in our laboratory. Firstly, the paper gives a brief introduction of three kinds of typical methods of optical detection, then highlights the surface shape deviation detection method as well as its main evaluation indexes, and detailedly describes the link between these indexes. Next, the paper applies Matlab language grogramming to digitize the image of the interference fringes collected by interferometer. This paper also clearly details the process of the interference fringe image and comparatively analyses the processing of each step. At the end of the paper, the correlation theory and fitting algorithm of Zernike polynomial wavefront fitting and interpolation wavefront fitting are introduced detailedly as well, and these algorithms are applied to make wavefront fitting of interference fringes to abtain the surface shape deviation information(PV and RMS) from detected optical parts, the wave information and the information detected by Zygo interferometer are compared as well, including estimation and analysis of this two kinds of wavefront fitting errors, and the reasons that may cause measurement errors are identified and some improvement schemes are proposed.In the end, this paper summarize the fringes image processing research work and some improved ideas and methods for image processing and fitting aspects will be put forward in the future.