| 摘要 |
PROBLEM TO BE SOLVED: To make the diameter of a doublet smaller and to effectively compensate aberration, while realizing improvement in f-number and a wider angle in a projection lens device used for a projector device. SOLUTION: A 1A-th lens group and a 1B-th lens group are arranged on the front side of a diaphragm A, and a 2nd lens group is arranged on the rear side of the diaphragm. The doublet, having negative power and opposed to the diaphragm A, is provided in the 2nd lens group. A correction lens L6 having positive power is provided to be positioned immediately in front of the diaphragm A. The height of a light beam made incident on the doublet is restrained by the lens L6, and the doublet is restrained from becoming large. Since the lens L6 is arranged in close proximity to the diaphragm A, spherical aberrations and coma aberrations are corrected effectively.
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