| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical heterodyne interferometer for two-dimensionally measuring a configuration of a measurement object without using an electronic shutter function of a CCD camera. SOLUTION: Out of two beams radiated from a light source LS, one beam passes through a measurement face of the measurement object 2, and the other beam has a different frequency and passes through a reference face Mr. An interference pattern is generated by the interference of two beams and observed by a plurality of detection elements. A heterodyne signal is obtained from each detection element and referred to a reference signal having the same frequency. A phase shift is generated in each heterodyne signal and detected. Thus, the shape of the measured face is measured. The operations of synchronizing the beams with the reference signal to enter the beams into the measurement face and the reference face Mr for a constant period and to determine an integrated value of the heterodyne signal for the constant period are synchronously implemented at three or more locations having different phases in one cycle of the reference signal. At least three integrated values are determined. The phase shift of the heterodyne signal to the reference signal is detected based the integrated values. COPYRIGHT: (C)2004,JPO
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