Computational Theory The processing of biological specimens or the 2.1 Overview examination of material surfaces for quality control requires a fast and precise autofocus system. In order to process several fields of view per second, a high speed autofocus was developed and integrated in an ASIC-chip. The system is able to process a specimen without any supervision. The system operates on the well known dual-out-of-focus principle by using three images in three different focal planes, where

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... iple standard CCD-cameras are used for autofocus, each one with an 8 bit digitizer running at a pixel rate of 14.2MHz. By taking every half image of the interlaced TV-frame, 50 measurements per second are made. With the results from three different focal planes, the determination whether the current scene is already in focus or not. can be made within 20 milliseconds. The system is controlled by a microprocessor which is moving the scanning stage from field to field and which focusses the scenes. The software is made intelligent by the way that it learns, how to use the statistical properties of the investigated surface to predict the position of the next focal plane.