| 摘要 |
PURPOSE:To enable highly accurate measurement regardless of a surface state, by evaluating the irregularity of a light receiving picture element by receiving respective reflected beams of a plurality of laser beams by image sensors of a plurality of phases and correcting an error due to the state of a measuring surface. CONSTITUTION:Laser beams 10A simultaneously generated from a plurality of light sources 10, for example, five light sources are reflected from a measuring objective surface 12 and respective reflected beams 10B are received by the image sensor of a plurality of phases of a light receiving element 14 at a position different from the light sources. Beam receiving output is applied to an electronic circuit 16 and the irregularity of the address of a light receiving picture element in each phase of each of simultaneously received reflected beams is evaluated by calculating the average value (N1+N2...+N5)/5 of center- of-gravity positions N1-N5 and this average value is used as a correction value for correcting an error due to the surface state of the surface 12. Therefore, regardless of the surface state, a position can be measured with high accuracy using laser beam.
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