Importance

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Abstract

Telecentric projection lenses are disclosed which are precise in terms of their F number and which have a high resolving power and high contrast, namely well corrected spherical aberration, coma, curvature of field and distortion, and are intended for use at aperture efficiency of 100% and at magnification of about 1/10. The telecentric projection lens comprises a first lens group consisting of a positive single lens, a second lens group consisting of a negative single lens and a third lens group consisting of two positive lenses, arranged in this order as viewed from the object field side. The lens of the second group is a double concave lens and one of the positive lenses in the third group has a cemented surface whose center of curvature lies on the side of object field. The focal lengths f.sub.1, f.sub.2 and f.sub.3 of the first, second and third groups and the focal length f of the whole lens system satisfy the following conditions: 1.69.ltoreq..vertline.f.sub.1 /f.sub.2 .vertline..ltoreq.2.55 -0.33.ltoreq.f.sub.2 /f.ltoreq.-0.19 0.41.ltoreq.f.sub.3 /f.ltoreq.0.59.

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First Claim