TELECENTRIC PROJECTION LENS WITH LONG WORKING DISTANCE

摘要

PURPOSE:To compensate comma aberration to screen circumferential lumnous flux excellently while preventing negative distortion by setting an air gap much longer than the overall length of a lens and obtaining long working distance. CONSTITUTION:The lens system has a negative front lens group of a positive and a negative single lens L1 and L2 or their cemented lens which is negative on the whole, the large air gap, a positive lens L3, a biconcave lens L4 having an intense convex surface on the object side, etc., successively from the screen side. Consequently, the air gap much longer than the overall length of the lens system is set and the long working distance is obtained to compensate comma aberration to the screen circumferential luminous flux while preventing negative distortion.