10 August 1998 Digital optical profiler with automatic reference phase calibration
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Abstract
A digital optical profiler has been developed by our group. It is based on a Linnik interference microscope. The high precision measurement is obtained by introducing the phase-stepping interferometry. The phase stepping procedure is implemented by applying the high voltage to a piezoelectric transducer (PZT) and forcing it to extend or compress. It is commonly known that the PZT components have strong nonlinearity. So it is very difficult to obtain accurate reference phase steps. An effective A-bucket phase-stepping algorithm has been proposed by Okada et.al., G.S.Han et.al.,I.B.Kong et.al., and S.W.Kim et.al.,respectively. The algorithm is insensitive to reference phase stepping errors and each phase step can be calculated by iterative least-squares fitting. However, the initial values of the iteration are given by guessing. A new initial values determination method is presented in this paper. The new method calculates the initial phase steps by means of one dimension FFT. The measurement results confirm that the new method is very effective. Because of the new method, the reference phases can be automatically calibrated on line. The about 0.4 nm repeatability of Ra measurement can be achieved without vibration-resistant system. The profiler has good prospect in the measurement of smooth conventional optical components, optical disk, optoelectronics devices etc..
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Chunlong Wei, Chunlong Wei, Mingyi Chen, Mingyi Chen, Zhijiang Wang, Zhijiang Wang, } "Digital optical profiler with automatic reference phase calibration", Proc. SPIE 3558, Automated Optical Inspection for Industry: Theory, Technology, and Applications II, (10 August 1998); doi: 10.1117/12.318441; https://doi.org/10.1117/12.318441
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