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:
Dec. 25, 1990
Filed:
Apr. 11, 1990
Kazuhiko Matsuoka, Yokohama, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A biaspherical single lens for an optical information recording-reproducing apparatus comprises a single lens forming an image through a substrate of thickness t and having its first and second surfaces both formed by an aspherical surface and in which when the distance from any point on the aspherical surface to the tangential plane of the vertex of the aspherical surface is X and the distance from said any point to the optic axis is H and the reference radius of curvature of the .nu.th surface is R.sub..nu. and the cone constant of the .nu.th surface is K.sub..nu. and the aspherical coefficient of the .nu.th surface is A.sub..nu.i (i=3, 4, . . . ), the aspherical surface is an aspherical surface expressed by the following equation and satisfies the following conditions (1), (2), (3) and (4): ##EQU1## where F is the focal length of the aspherical single lens, D is the thickness on the optic axis of the aspherical single lens, and N is the refractive index of the aspherical single lens for the wavelength used.