Two-dimensional surface profile imaging technique based on a double-grating frequency shifter |
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Authors: | Wang Kaiwei Zeng Lijiang |
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Affiliation: | State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 100084, China. wkw01@mails.tsinghua.edu.cn |
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Abstract: | A two-dimensional surface profile imaging technique that uses a low-coherence heterodyne interferometer is proposed. A double-grating frequency shifter was used in a tandem interferometer to provide the achromatic frequency shift for low-coherence light. A chopper, together with a processing circuit, was implemented to modulate the interference fringes. The surface profile was measured from the interference fringes taken by a CCD camera using a five-step method. The uncertainty in the displacement measurement is 0.34 microm for a displacement range of 43 microm. The surface profile of a glass sample with low effective reflectivity was acquired. |
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