title: Measurement of period difference in grating pair based on compensation analysis of phase difference between diffraction beams.
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.
authors.affiliation: State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 100084, China. guoc@mails.tsinghua.edu.cn
authors.forename: Chao
authors.initials: C
authors.lastname: Guo
authors.forename: Lijiang
authors.initials: L
authors.lastname: Zeng