Modified polarization point diffraction interferometer with extended measurable NA for spherical surface testing

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• 作者：Daodang Wang ; Fumin Wang ; Yongying Yang ; Yongmo Zhuo
• 关键词：Optical testing ; Point diffraction interferometry ; Spherical surface testing ; Large pinhole ; Polarization
• 刊名：Optik - International Journal for Light and Electron Optics
• 出版年：2013
• 出版时间：November, 2013
• 年：2013
• 卷：124
• 期：22
• 页码：5481-5485
• 全文大小：1475 K

文摘

The small pinhole of point diffraction interferometer based on pinhole-point diffraction places ultra-high requirement on both the adjustment of testing system and performance of CCD camera. Besides, poor fringe contrast due to the low reflectivity of test spherical surface would limit the measurement precision in the processing of fringe pattern. A modified polarization point diffraction interferometer with extended measurable numerical aperture (NA) is presented for testing the spherical surfaces with low reflectivity. Measurement error factors as well as the corresponding calibration procedure are introduced in detail. Comparing with the results of Zygo interferometer, measurement accuracy with root-mean-square (RMS) value about 0.0026¦Ë and peak-to-valley (PV) 0.0134¦Ë is achieved. The system has good measurement repeatability, and the standard deviation of measurement results RMS better than 0.0010¦Ë is obtained. The proposed interferometer reduces the difficulty in the adjustment of the system and provides a feasible way for testing the surfaces with low reflectivity and high NA.