Automatic alignment is a computationally intensive task that slows some manufacturing processes which require it. In order to improve alignment speed we have designed a sensor that combines the imaging operation with the computation of the alignment error. The sensor is specially designed to work with the surveyor's mark in a two step operation. Coarse alignment is performed by operating as a four quadrant sensor and fine positioning is achieved using edge detection. Photodiodes are used for imaging and integrated amplifiers convert the photocurrents into an alignment error signal which is independent of illumination level. A version of this sensor has been fabricated and preliminary tests show that it functions as expected.
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