| 摘要 |
PROBLEM TO BE SOLVED: To provide highly accurate measurement of thickness distribution of a thin plate-like measuring object using a simple device configuration without being influenced by vibration of the measuring object. SOLUTION: For the front and back surfaces of the measuring object 1, the light beam emitted from a laser light source 2 is split into two light beams, each split beam is further split into two light beams, the light beams are reflected on the reference surface and at measurement points 1a and 1b opposite each other on the respective front and back surfaces, non-interference light beams Pax and Pbx having the mutually perpendicular polarized components of which are the reference light beam and the object light beam are acquired, and the acquired non-interference light beams are split into multiple light beams. One or more split light beams among the split light beams are phase shifted by varying the phase differences among the polarized components perpendicular to one another by means of wavelength plates a261, a263, and a264 and so forth, the common polarized components when the polarization directions of the reference light beam and object light beam of the split light beams after the phase shift are used as references are extracted, and thereby interference light beams Qa1 to Qa4, and Qb1 to Qb4 are obtained. The phase difference between the polarized components of the reference light beam and the object light beam of the non-interference light beam is calculated from the intensities thereof, and the distribution of the thickness of the measuring object 1 is calculated from the distribution of the phase differences. COPYRIGHT: (C)2010,JPO&INPIT
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