Research On Measuring Technology Of Optical Lens Decentration

In the optical system. Lens is treated as the most basic optical components, and the positioning accuracy of lens center directly affects the imaging quality of entire optical system. Therefore the measuring technology of optical lens decentration has important significance. The measurement of lens decentration in the processing is an essential link. By measuring the size of decentration, processing the lens in real-time is an important method to improve the quality of the lens. In optical system, only ensuring the coaxality can guarantee the imaging quality of system. Therefore, the research on detection technology of lens decentration is one of the basic requirements in improving the optical system precision.Based on the theoretical knowledge of the measurement technology of lens decentration, this paper used Matlab to analyze and built the experiment platforms.The main works completed are as follows:Firstly, through consulting the information at home and abroad, the measuring method of lens's center errors is systematic discussion. And the advantages and disadvantages of interfering method, reflection method and transmission method are contrasted to select the measurement of decentration method which is based on principle of equal thickness interference of polarized light. The principle of the equal thickness interference of polarized light is analyzed. And the software is written to intuitive show the relationship between the effective of interference ring, the light wavelength source and the air layer thickness.Secondly, according to the principle of measurement of decentration. the basic test system including optical system, collecting system and processing system is designed. Analyzing the requirements and characteristics of whole system, appropriate optical element and image acquisition system are chose to achieve interference image with high quality.Thirdly, the processing algorithm about image processing is researched. Based on Matlab development environment, the digital image acquisition and processing software are built to obtain and process the interference image. The main works are completed the image processing. such as inputting,enhancing,binary, thinning,fitting circle and computing center errors and so on. According to the measurement results, the algorithm precision and the source of the errors are analyzed. Further more, the method of improving system and precision are put. Due to the influence of the external environment and complexity of double interference rings, the processing of the interference ring become one of the key parts in improving precision.Finally, building experimental platform, testing of lenses is completed to get interference images. According to the experimental pictures, a series of the existing error factors in the experiment is analyzed, which provides conditions for future improvement of measurement system.With the researches of this thesis, the theoretical research and experimental analysis in measurement of lens decentration are completed. The results prove that the method can also measure the decentration of the top and bottom surfaces. This algorithm is very effective with the non-uniformity light, the image of low contrast and inferior which can be used in the measurement in optical lens decentration.