Device for the automatic focussing of optical instruments with complementary measuring and detecting diaphragms

摘要

For the automatic focussing of an optical instrument on an object, a measuring diaphragm is inserted into the illuminating radiation path, which diaphragm is to be projected onto the object plane and focus plane during focussing. This intermediate image of the measuring diaphragm is projected via a detector diaphragm which is complementary to the measuring diaphragm, onto a detector, the output signal of which is a scale for the quality of the focussing and which acts on a focussing drive in the sense of optimum focussing via a control device.