Dynamic Twyman Interferometer for Phase Defect Measurement
(2.School of Electronic and Optical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu, China 210094)
【Abstract】In order to realize the large field, high resolution and dynamic measurement of optical component phase defects, we design a dynamic Twyman interferometer. Based on low-coherence laser and Michelson interferometer, a pair of orthogonal polarized light produced with phase delay is used as light source. By phase matching of the interference cavity, the phase delay between reference light and test light is compensated. The polarization camera is used to collect four interferograms with phase-shifting step of π/2, and the information of the phase defect is solved by phase-shifting algorithm. The effect of secondary diffraction on measurement results is analyzed based on the theory of the angle spectrum of plane wave. The influence of the polarizer error on the measurement results is analyzed by Jones matrix method. In the experiment, a laser-damaged optical plate is measured by this interferometer and Veeco NT9100 white light interferometer, and the relative error is 2.4%. In addition, this method is used to detect phase defects of optical flat in high power laser system, and the peak-to-valley value of wavefront is 199.2 nm. The results show that the interferometer can be used to detect phase defects of optical components, effectively.
【Keywords】 measurement; dynamic interferometry; phase defect; spatial phase-shifting; low-coherence light source;
 Miller P E, Suratwala T I, Wong L L, et al. The distribution of subsurface damage in fused silica [C]. SPIE, 2005, 5991: 599101.
 Suratwala T I, Wong L L, Miller P E, et al. Sub-surface mechanical damage distributions during grinding of fused silica [J]. Journal of Non-Crystalline Solids, 2006, 352 (52/53/54): 5601–5617.
 Golini D. Transition between brittle and ductile mode in loose abrasive grinding [C]. SPIE, 1990, 1333: 80–91.
 Zhang Bo, Ni Kaizao, Wang Linjun, et al. New algorithm of detecting optical surface imperfection based on background correction and image segmentation [J]. Acta Optica Sinica, 2016, 36 (9): 0911004 (in Chinese).
 Luo Mao, Bu Yang, Xu Jinghao, et al. Optical element surface defect measurement based on multispectral technique [J]. Chinese J Lasers, 2017, 44 (1): 0104001 (in Chinese).
 Bercegol H, Bouchut P R, Lamaignere L, et al. The impact of laser damage on the lifetime of optical components in fusion lasers [C]. SPIE, 2004, 5273: 312–324.
 Sommargren G E, Phillion D W, Johnson M A, et al. 100-picometer interferometry for EUVL [C]. SPIE, 2002, 4688: 316–328.
 Arima K, Shigetoshi T, Inoue H, et al. Nano-scale characterization of surface defects on CMP-finished Si wafers by scanning probe microscopy combined with laser light scattering [C]. MRS Online Proceedings Library, 2007, 991: 227–232.
 Stover J C. Use of new technology for enhanced detection of crystalline defects on silicon wafers [C]. SPIE, 1998, 3275: 138–144.
 LüXiankui, Tao Chunkuang. Phase disfigurement for transparent material [J]. Nondestructive Testing, 2004, 26 (11): 552–553 (in Chinese).
 Ravizza F L. Imaging of phase objects using partially coherent illumination [D]. Livermore: Lawrence Livermore National Laboratory (LLNL), 2013.
 Millerd J E, Brock N J, Hayes J B, et al. Pixelated phase-mask dynamic interferometer [C]. SPIE, 2004, 5531: 304–314.
 Brock N J, Hayes J B, Kimbrough B T, et al. Dynamic interferometry [C]. SPIE, 2005, 5875: 58750F.
 Kimbrough B T. Pixelated mask spatial carrier phase shifting interferometry algorithms and associated errors [J]. Applied Optics, 2006, 45 (19): 4554–4562.
 Goodman J W. Introduction to Fourier optics [M]. Qin Kecheng, Transl. Beijing: Publishing House of Electronics Industry, 2011: 40–43 (in Chinese).