Four-group zoom lens

Details Four-group zoom lens Four-group zoom lens

2006-01-03

2006-01-03

Sugarman, Scott J. (Department: 2873)

Optical: systems and elements

Lens

With variable magnification

C359S683000

Reexamination Certificate

active

06982835

ABSTRACT:
A four-group zoom lens that corrects aberrations in the visible and near infrared regions includes, in order from the object side, a first lens group of positive refractive power, a second lens group of negative refractive power, and third and fourth lens groups, each of positive refractive power. Only the second and fourth lens groups move during zooming. The first lens group includes a negative lens element on the object side of second, third, and fourth lens elements that each have positive refractive power and a convex lens surface on the object side. Aspheric lens surfaces are disclosed. Certain conditions are satisfied by the ratio of focal lengths of the first lens group and the zoom lens, and, in the first lens group, by the Abbe numbers of the first and second lens elements and the index of refraction of the second lens element.

REFERENCES:
patent: 5583699 (1996-12-01), Nakayama
patent: 5886828 (1999-03-01), Kim
patent: 6404561 (2002-06-01), Isono et al.

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