Afocal telescopes

Details Afocal telescopes Afocal telescopes

1999-05-03

2000-04-11

Nguyen, Thong

Optical: systems and elements

Lens

Afocal

359356, 359362, 359399, G02B 1300, G02B 1314, G02B 2300

Patent

active

060494344

ABSTRACT:
An afocal telescope operating in the thermal infra-red waveband has a three-element objective comprising a positively-powered central lens element disposed between positively powered and negatively powered lateral lens elements, the positively powered lateral lens element being located proximal to the inter-mediate image and incorporating a hybrid surface simultaneously to correct longitudinal and field colour, and wherein one of the positively powered lens elements of the objective is made of a material having a negative temperature refractive index co-efficient and has an optical power selected to render the telescope athermal.

REFERENCES:
patent: 4398786 (1983-08-01), Neil
patent: 4479695 (1984-10-01), Neil
patent: 5044706 (1991-09-01), Chen
patent: 5251063 (1993-10-01), Baumann
patent: 5838489 (1998-11-01), Erdmann
patent: 5880879 (1999-03-01), Foo

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