Optical measurement arrangement

摘要

An illumination device (12) projects a light beam onto the object surface limited by a stop blade (14). A lens (160 forms an image of the light reflected from the surface and an image sensor (20) scans the image plane (18) in the direction of the stop blade. An evaluation circuit determines the surface height coordinates from the sensor signals. The evaluation circuit (10A,10B) contains a transducer (24) forming a signal corresp. to the average line intensity for each scanned image line during a scan period; a threshold generator (32) dependent on the mean intensity; a comparator (26) which compares the line intensity signals with the threshold and a display stage (28) for the height coordinate corresp. to the position of the image line pair either side of a threshold transition.