位相シフトを導入したモアレトポグラフィ法による反射物体の測定

概要

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Phase-shifting moire topography system has been developed for the profile measurement of reflective objects such as optical disks. The collimated laser beam incident on the grating produces Fourier images due to diffraction. The image with different diffraction order deforms in accordance with the surface profile of the object behind the grating. The deformed pattern reflects back to the reference grating and, after superposition on the grating it produces moire fringe which gives the contour of the surface. The order of the diffracted beam can be chosen by the iris stop of the CCD camera arranged in telecentric optics for contour observation. In this trial low sensitivity inherent to the conventional moire method can be overcome by phase-shifting technique utilized in interferometric measurement. The hill or valley of the surface can also be identified by computation hased on this principle. Our development can bring the sensitivity of 3 μm in contour interval and the depth of observation ranging 70 μm which are not appropriate for the interferometric measurement.
1992-11-05