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:
Feb. 18, 1997
Filed:
Jul. 27, 1993
William R Hunter, Springfield, VA (US);
James P Long, Accokeek, MD (US);
The United States of America as represented by the Secretary of the Navy, Washington, DC (US);
Abstract
A thin film reflecting interference filter (RIF) is designed to suppress unwanted harmonics thereby improving the monochromaticity of the radiation. An interference layer of material which has a well-defined plasma oscillation is deposited on a substrate and a mismatch layer is formed thereon. This interference layer exploits the interference between wavefronts reflected from the layer-substrate and the vacuum-layer interfaces to suppress higher order harmonics, while allowing good reflectance at the fundamental wavelength. This is achieved by positioning the RIF in the radiation at an angle of incidence which is greater than the critical angle of the desired fundamental wavelength, but less than critical angles of the harmonics to be suppressed. The mismatch layer increases the reflectance of the unwanted harmonics at the vacuum-layer interface, thus allowing more complete destructive interference of the unwanted harmonics. The RIF can be tuned by altering the thickness of the layer, the composition of the layer and/or the angle of incidence of the radiation.