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:
May. 30, 2000
Filed:
Aug. 17, 1998
Noboru Koizumi, Omiya, JP;
Naomi Watanabe, Urawa, JP;
Fuji Photo Optical Co., Ltd., Omiya, JP;
Abstract
A wide-field eyepiece, formed of at least four lens groups and five lens elements, is disclosed which satisfies predetermined conditional expressions, so as to provide an eyepiece having an angle of view of at least 65 degrees with less than 6% distortion. The wide-field eyepiece is formed of, in order from the side of an image position 1 formed by an objective lens (not illustrated): a first lens group G.sub.1 of negative refractive power that includes a first lens element L.sub.1 having a concave surface on both sides, a second lens group G.sub.2 of positive refractive power that includes a second lens element L.sub.2 having a convex surface on the side of an observer's eye position, a third lens group G.sub.3 of positive refractive power wherein a lens element surface thereof has a convex surface on both sides and is cemented to a negative lens element having a concave surface on the side nearest the image 1 formed by the objective lens; and a fourth lens group G.sub.4 of positive refractive power and including a lens element with different radii of curvature on its opposite sides, with the surface of larger radius of curvature lying on the side of an observer's eye position.