Phase shifting interferograms processing for fiber point-diffraction interferometer

Liang Nie; Jun Han; Xun Yu; Baoyuan Liu; Xu Jiang; Fang Wang

doi:10.1117/12.814552

3 October 2008 Phase shifting interferograms processing for fiber point-diffraction interferometer

Liang Nie, Jun Han, Xun Yu, Baoyuan Liu, Xu Jiang, Fang Wang

Proceedings Volume 7155, Ninth International Symposium on Laser Metrology; 71551G (2008) https://doi.org/10.1117/12.814552
Event: Ninth International Symposium on Laser Metrology, 2008, Singapore, Singapore

Abstract

To characterize the spherical surface of extreme ultraviolet (EUV), the fiber phase shifting point-diffraction interferometer (FPS/PDI) has recently been designed and implemented. The diffraction wavefront from an optical fiber acts as the perfect referenced spherical wave and new-style interferometer configuration is used. The laboratory apparatus has been put up to measure spherical surface in experiment. The main content of this paper is the key technique of FPS/PDI about the method of interference image processing and the precision analysis for the interferometer. In experiment apparatus, a concave spherical surface is measured and a piezoelectric ceramics (PZT) is used for phase shifting. The wrap phase distribution is got by five-step phase shifting method, and then the unweighted least-squares phase unwrapping algorithm is optimized and used to obtain the unwrapped phase distribution. The error of spherical figure is derived from the fitting method of Zernike polynomials. The data processing result is analyzed in comparison with the measurement result of ZYGO interferometer. The repeat precision of the FPS/PDI is evaluated by multimeasurement. Finally, the major error sources are discussed and some optimized methods for the system are proposed.The results show that the interferometer has achieved worthy measurement precision and has great development potential.

Citation Download Citation

Liang Nie, Jun Han, Xun Yu, Baoyuan Liu, Xu Jiang, and Fang Wang "Phase shifting interferograms processing for fiber point-diffraction interferometer", Proc. SPIE 7155, Ninth International Symposium on Laser Metrology, 71551G (3 October 2008); https://doi.org/10.1117/12.814552

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