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2 February 2009 An improved image matching technique for detecting piston
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To achieve a good quality of image, piston of segment mirrors is required to be detected and removed down to a small part of λ. The details of the diffraction-interference pattern formed by the subaperture are sensitive to piston when observed on the image plane. An improved image matching method is introduced to detect piston according to the characters of the interference-diffraction patterns. Templates are made according to the parameters of the system. One-dimension projecting production-moment correlation method and projecting central moment eigenvector method are used in different conditions. The great advantage of this method is that there is no need of calibration so the measurement error is reduced. The operation is simplified to reduce the computation complexity by three matching steps. The measurement range is about um 25 ±um and the measurement error is less than 10nm. The experiment is carried out on a platform. Piston is introduced to the parallel-light by a piston generator which is controlled by a PZT. CCD with the pixel size 4.65um*4.65um is used to receive the image. The experiment result is basically consistent with the theory.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Dan-dan Qu, Yue-jin Zhao, Mei Hui, and Fei Yu "An improved image matching technique for detecting piston", Proc. SPIE 7160, 2008 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Applications, 71602H (2 February 2009);

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