AUTOMATIC CONTRAST FOCUSSING WITH THREE OPTICAL PATHS

摘要

The invention relates to a method and a device for determining the distance from a point (10) on an object (12) to a sensor (14, 20, 22) by measuring the contrast values of the point that is represented in the working plane of the sensor. According to the invention, the contrast distributions of the beams are determined at the ends of at least three optical paths of different lengths in the imaging beam path of the optical system (18) according to the distance to the point of the object to be measured, using at least one sensor, and a relationship is established between the resulting contrast distributions. In this way, the distance between the object and the sensor can be determined quickly and accurately.