OPTICAL DISPLACEMENT SENSOR

摘要

The present invention relates to a compact and inexpensive optical displacement sensor that does not require accurate control of the distance t o the object. A repetitive optical structure is utilized for formation of a repetitive optical signal emitted by an illuminated moving object. The repetitive optical structure is illuminated by the light source for formatio n of a fringe pattern (similar to Laser Doppler Anemometry), and/or, an object is illuminated by the light source and the repetitive optical structure diverts light from the illuminated object onto light sensors. A speckle pattern is formed on the object by the illumination. The speckle pattern mov es with movement of the object, and speckle pattern movement is determined without a need for imaging the object onto the repetitive optical structure. Since the speckle pattern is not imaged onto the optical member, the distanc e and possible distance changes between the object and the optical member substantially do not affect system performance.