Optical system for imaging an object, while maintaining the focusing, regardless of a change in the distance between the object plane and the image plane

摘要

An optical system is described for imaging an object in a plane, the focussing being maintained independent of a variation in the length of the optical path between the object plane and the image plane. By using a first, stationary lens system which forms a reduced image and a second, movable lens system which forms an enlarged image, the system can be readjusted using relatively low power.