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:
Sep. 15, 1992
Filed:
May. 01, 1991
Sadao Mori, Ibaraki, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
There are disclosed an automatic focusing apparatus and an automatic focusing method for an optical disk apparatus. The present automatic focusing apparatus comprises a light source for outputting an optical beam to be focused; a focusing optical system for focusing the optical beam to be focused onto a desired position by using a photorefractive crystal having a lens effect; a device for forming a refractive-index distribution forming beam having a predetermined intensity distribution and outputting the beam onto the photorefractive crystal to generate a lens effect in the photorefractive crystal; a control beam outputting device for outputting a control beam onto the photorefractive crystal to control the lens effect caused by the refractive-index distribution generated in the photorefractive crystal; and a device for controlling the control beam outputting device. Focus adjustment is thus made without moving the lens.