| 摘要 |
1,218,704. Lenses. INTERNATIONAL BUSINESS MACHINES CORP. July 1, 1969 [July 15, 1968], No.33044/69. Heading.G2J. A lens system, e.g. a reduction lens, comprises nine optically aligned lens elements, the first, second, fifth, eighth and ninth elements being singlet lenses, the third and fourth elements forming a first doublet, the sixth and seventh elements forming a second doublet, and a diaphragm optically aligned with the elements and positioned edjacent the fifth lens element. The first and second elements are positive meniscus lenses, the third and fourth together form a positive meniscus lens, the fifth lens may be a positive meniscus, the sixth and seventh elements together form a negative meniscus lens, the eighth element is a negative meniscus lens and the ninth element is a bi-convex lens. If desired the fifth element may be bi-concave. Optical data for two examples is given. |
