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:
Apr. 13, 1993
Filed:
Jul. 22, 1991
Hiroyuki Sugawara, Hitachi, JP;
Toshiharu Shirakura, Toukai, JP;
Takeshi Yamamura, Hitachi, JP;
Hideki Yamai, Hitachi, JP;
Hitachi, Ltd., Tokyo, JP;
Hitachi Engineering Co., Ltd., Ibataki, JP;
Abstract
The present invention relates to a laser oscillator, especially to a laser oscillator suitable for ultrafine manufacturing such as an apparatus for manufacturing of a semiconductor wherein the laser oscillator is provided with constant directivity chronically, although the directivity is not so fine, for avoiding a blurred image spatially and chronically in order to obtain a stable mask in the ultrafine manufacturing. The laser oscillator includes apparatus for enabling at least one of selection of the directivity of parallel light from a resonator between a whole reflector and a laser medium; an optical system for stopping oscillation of the laser medium before a laser beam, which is generated at the resonator, becomes a single mode and for eliminating the laser beam having poor directivity; prevention of the laser medium from re-entry of unnecessary natural emitting light which is generated in the laser medium; and providing a value of a diameter of an aperture of the optical system for maintaining directivity so as to make an order number of the transverse mode high.