Large numerical aperture objective lens and night vision...

Details Large numerical aperture objective lens and night vision... Large numerical aperture objective lens and night vision...

2005-01-04

2005-01-04

Nguyen, Thong Q (Department: 2872)

Optical: systems and elements

Lens

With variable magnification

C359S353000, C359S785000

Reexamination Certificate

active

06839186

ABSTRACT:
A large numerical aperture objective lens is disclosed having three lens groups. In order from the object side, these lens groups include: a first lens group of positive refractive power that is formed of two positive lens elements and an achromatic set of paired lens elements formed of a lens element of negative refractive power and a lens element of positive refractive power, respectively; a second lens group of negative refractive power; and a third lens group of positive refractive power, with the surface of the third lens group nearest the object side being convex. Specified conditions are satisfied in order to provide a compact, large numerical aperture objective lens having its aberrations favorably corrected as well as to correct for shifts of focus caused by expansion/contraction of the lens barrel with changes in temperature. The objective lens of the invention is particularly suitable for use in a night vision optical device having a photoelectron amplifier tube and an eyepiece, wherein aberrations in the eyepiece are balanced by aberrations of the objective lens.

REFERENCES:
patent: 4610514 (1986-09-01), Nakamura
patent: 6317275 (2001-11-01), Yoneyama
patent: 6384975 (2002-05-01), Hayakawa
patent: 6600609 (2003-07-01), Yamakawa
patent: 7-95143 (1995-10-01), None

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