| 摘要 |
<p>PURPOSE:To surely attain the changing action of a detected moving ratio by changing the average size of speckles on the light receiving face of a photodetector 2 within a prescribed area so that the detected moving ration can be almost proportionally changed. CONSTITUTION:Since the average size D of speckle patterns on the light receiving face of the photodetector 2 is variably set up within the prescribed area E, the moving ratio J detected by the photodetector 2 is almost proportionally changed in accordance with the average size D of the speckles. If a speckle pattern SP is moved in the arrow direction at a fixed velocity (v) when the photodetector 2 consisting of a pair of photodetecting elements 2a, 2b, signal intensity detected by one photodetecting element 2a positioned on the prestige in the moving direction of the speckle pattern is almost the same as the photodetecting element 2b positioned on the post stage in the moving direction before only a certain time tau.</p> |
