DEVICE FOR MEASURING LIGHT WAVE INTERFERENCE

摘要

PROBLEM TO BE SOLVED: To shorten a measuring time by improving position precision of an optical wedge in a measuring device for light wave interference measuring based on waveforms of shading of interference fringe, resulting from shifting of the interference fringe caused by moving the optical wedge. SOLUTION: Shading information of interference fringe is acquired by moving the optical wedge 50 with a wedge angle r in a main optical path 32 at a constant speed of S and by shooting the interference fringe with a CCD camera 46 of a frame rate f. It is possible to suppress distortion of shading waveforms when an interval of shooting is taken below a quarter of the period of shading of the interference fringe. Here, adopting the wavelength of light used for measuring, the traveling speed S of the optical wedge is expressed as the following expression, S≤λf/(4tan-1r). Thus, position precision can be enhanced, because errors of stopping place are cleared off without stopping of the optical wedge. Furthermore, shortening of measuring time can be attempted because subsiding of vibration while stopping is avoided the need to wait. COPYRIGHT: (C)2006,JPO&NCIPI