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. 14, 1976
Filed:
Nov. 05, 1975
Paul L Kebabian, Somerville, MA (US);
Environmental Research & Technology, Inc., Concord, MA (US);
Abstract
An optical system is provided to minimize the angle-dependent transmission characteristics of interference filters, the optical system including a light equalizer having an output aperture across which each area element exhibits substantially the same emission intensity regardless of the distribution of light into the input aperture of the equalizer. The output aperture of the equalizer is disposed at the focal surface of collimating optics and the resultant collimated light constitutes the input to the interference filter. The equalizer is embodied in a transmissive element which is divided into pairs of transmissive channels, the number of such pairs increasing with the distance from the input aperture. The interface between the adjacent channels is, at least in part, leaky as by being substantially half transmissive half reflective. The exterior surface of the equalizer is covered with an internally reflective coating except for the input and output apertures.