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:
Mar. 12, 1991
Filed:
Nov. 01, 1989
Isao Matsumura, Yokosuka, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
The corneal reflection virtual image of an index mark for cornea shape measurement is displaced by a variation in the working distance, but a light beam regulating device for extracting the corneal reflection light whose principal light ray is a light ray corresponding to the direction of displacement thereof is provided at a particular position in a cornea shape measuring optical system to thereby eliminate any measurement error based on the variation in the working distance. When a different region of the cornea is to be measured with the index mark displaced in the direction of the optic axis, a predetermined principal light ray conforming to the position of the index mark in the direction of the optic axis is caused to enter the light beam regulating device.