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:
Nov. 29, 2011
Filed:
Sep. 23, 2009
Hideharu Okami, Chiba, JP;
Yoshiyuki Abe, Chiba, JP;
Tokuyuki Nakayama, Chiba, JP;
Sumitomo Metal Mining Co., Ltd., Tokyo, JP;
Abstract
In an absorption type multi-layer film ND filter having a thin substrate and provided thereon first and second absorption type multi-layer films which attenuate transmitted light, the first and second absorption type multi-layer films are constituted of multi-layer films each consisting essentially of dielectric layers formed of SiO, AlOor a mixture of these and metal film layers formed of Ni alone or an Ni alloy; the layers being alternately layered on the substrate; and the first and second absorption type multi-layer films are so formed on one side and the other side, respectively, of the substrate as to have a film structure in which they are symmetrical to each other interposing the substrate between them, and the warpage of the substrate has been controlled at a curvature of radius of 500 mm or more.