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Measurement of period difference in grating pair based on compensation analysis of phase difference between
1State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 100084, China. guoc@mails.tsinghua.edu.cn
Abstract:
We propose an experimental method for measuring the period difference in a grating pair. The method uses the relationship between the period difference and the phase difference of diffraction beams of the grating pair when gratings are translated along the grating-vector direction. The effect of the roll angular deviation of gratings can be eliminated by phase compensation with +1st- and -1st-order diffraction beams. Far-field intensity patterns of diffraction beams are monitored to adjust the relative attitude of gratings. For a pair of gratings with periods of approximately 0.674 microm, the period difference was measured to be 0.4434 nm with an expanded uncertainty (k=2) of 0.0113 nm.
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