Method for determining the position of a cross-line mark

摘要

The invention relates to a method for objectively determining the position of an optical cross-line mark in three degrees of freedom by imaging the mark on an x-, y- addressable image sensor. Compared with known solutions, considerable saving in processing time and required storage capacity in the image processing units is achieved. This is possible due to the fact that two rows at distance u and two columns at distance v are selected from the field of view of the sensor by using a field-of-view selection circuit. The cross-line mark is imaged on these rows and columns in such a manner that four points of intersection are produced from which the position of the point of intersection of the lines of the mark can be determined with the aid of the equation of lines and the tilt of the mark can be determined from the slope of one of the lines. One field of application of the invention would be, for example, the alignment of optical and mechanical components by means of an optical mark.