| 摘要 |
<p>PURPOSE:To stabilize position specifying operation by approximating a measured point group of pieces of relative movement information on a photodetector as to the rough surface of a body and pieces of output information of the photodetector corresponding to the respective pieces of relative movement information with a characteristic straight line. CONSTITUTION:When the photodetector 2 detects movement information M on a speckle pattern SP generated by the scattering of a coherent electromagnetic wave Bm by the body rough surface 1, the speckle rigidity ratio eta in an area E where the mean square error sigma of plural pieces of relative movement information on the photodetector 2 about the body rough surface 1 and respective measurement points corresponding to the pieces of relative movement information is converged to a nearly constant value is set according to the relation between the mean square error sigma and speckle rigidity ratio eta. In this case, the speckle rigidity ratio eta is in the specific area E, so a detection movement rate J is held constant even if the speckle rigidity ratio eta varies slightly.</p> |
