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:
Aug. 08, 2000
Filed:
Feb. 03, 1998
Ayami Imamura, Hachioji, JP;
Hitoshi Ohashi, Hachioji, JP;
Olympus Optical Company, Ltd., Tokyo, JP;
Abstract
An illumination optical system for cutting infrared light by a relief type optical element includes a light source and a relief type diffraction optical element having a rectangular sectional-shaped grating having an equal area of land and groove areas so that primarily zero order light can be used for illumination while higher order and infrared light may be filtered out. A relief pattern has characteristics such that a ratio .beta. of a width of a plurality of respective concave portions to a pitch of adjacent convex portions is in a range of 0.34.ltoreq..beta..ltoreq.0.66 and a groove depth d is in a range of 0.85 d.sub.0 .ltoreq.d.ltoreq.1.09 d.sub.0. Excessive heat from infrared light and higher order light may be eliminated without the use of an infrared cutter.