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. 19, 1995
Filed:
Feb. 23, 1995
Applicant:
Inventors:
Minouru Yoshii, Tokyo, JP;
Kenji Saito, Yokohama, JP;
Masayuki Suzuki, Zama, JP;
Hiroshi Osawa, Yokohama, JP;
Assignee:
Canon Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H15 / ;
U.S. Cl.
CPC ...
372-9 ; 372108 ; 372-7 ; 372 98 ;
Abstract
A phase shift device for a laser beam has a circular first area transparent so the laser beam and a second area provided around the first area and transparent to the laser beam. The first and second areas generate a phase difference for example 180.degree. in the passing light beams. The phase shift device is positioned for example at a beam waist of a laser scanning apparatus to form a beam spot of a diameter smaller than that defined by the numerical aperture of the imaging optical system. Structure of a laser apparatus employing such phase shift device is also disclosed.