Optical: systems and elements – Lens – With variable magnification
Reexamination Certificate
2011-05-17
2011-05-17
Spector, David N (Department: 2873)
Optical: systems and elements
Lens
With variable magnification
C359S680000, C359S691000, C359S676000
Reexamination Certificate
active
07944620
ABSTRACT:
A zoom lens includes a first lens group and a second lens group disposed between the first lens group and an image side. The first lens group has three lenses. Refractive powers of the three lenses arranged from an object side to the image side are respectively negative, negative, and positive. The second lens group has five lenses. Refractive powers of the five lenses arranged from the object side to the image side are respectively positive, negative, positive, negative, and positive. Effective focal lengths (EFL) of the first and the second groups are respectively f1 and f2. The EFL of the zoom lens is fwwhen the zoom lens is switched to a wide end. The zoom lens satisfies −2.8<f1/fw<−2.5 and 0.75<|f1/f2|<0.9.
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Lai Ching-Lung
Wang Kuo-Chuan
J.C. Patents
Spector David N
Young Optics Inc.
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