The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 11, 2000
Filed:
May. 03, 1999
Applicant:
Inventor:
David Gordon Norrie, Denbigh, GB;
Assignee:
Pilkington PE Limited, Wales, GB;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G02B / ; G02B / ; G02B / ;
U.S. Cl.
CPC ...
359744 ; 359356 ; 359362 ; 359399 ;
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.