| 摘要 |
PROBLEM TO BE SOLVED: To provide a measuring device which measures the displacement or the irregularity of an object surface with high accuracy. SOLUTION: A reflection light from the measuring plane X of the object is divided into two light fluxes by a half mirror BS2, the light quantity is measured with a photodiode PD1 via a pinhole A1 and the photodiode PD2 via the pinhole A2. The pinhole A1 is set at a position which is located at more remote position than the position of the focal length f1 of an ocular L1 located before the half mirror BS2, and the pinhole A2 is set at the position which is located at closer position than the position of the focal length f1. So, the light receiving quantities S1, S2 of the photodiodes PD1, PD2 are increased and decreased corresponding to the displacement of the measuring plane X, respectively. The displacement of the measuring plane X can be obtained with a high accuracy corresponding to the light receiving quantities S1, S2, by performing the preliminary measurement of the change of the light receiving quantities S1, S2 due to the displacement. COPYRIGHT: (C)2005,JPO&NCIPI
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