LENS WITH REMOVED ENTRANCE PUPIL ( VARIANTS ) Russian patent published in 2004 - IPC

FIELD: optics. SUBSTANCE: in compliance with both variants lens with removed entrance pupil has four components, second component being biconvex element. Last surface of third component faces image with concavity and fourth component comes in the form of negative meniscus facing object with concavity. Lens in agreement with first variant has first negative component cemented from biconcave and biconvex elements and third component is positive and cemented from biconvex and biconcave elements. Lens in correspondence with second variant has first component cemented from negative and positive meniscuses and faces object with concavity and its third component is made of biconvex and biconcave single elements placed with clearance of 1.0 mm between them. EFFECT: uniform high quality of image over entire field thanks to elimination of aberrations. 2 cl, 4 dwg, 4 tbl