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. 25, 2003
Filed:
Apr. 21, 1992
Allen J. Twarowski, Westlake Village, CA (US);
The Boeing Company, Chicago, IL (US);
Abstract
A reversible thermochromic optical limiter incorporates a thermochromic material, such as a spiropyran, that has molecules present in one of two states. At ambient temperatures the material is transparent to light. Incident laser radiation causes localized heating that turns the material to a colored state, effectively limiting transmission of the laser radiation. A laser protection device may comprise an optical focusing assembly, a nonlinear thermochromic medium, and a collimating assembly. A far field image having an intrusive laser beam, is focused through the thermochromic medium. The laser beam is focused to a small volume, causing localized heating, a large increase in optical density, and absorption of the laser light. The thermochromic medium has a fast response time over a broad wavelength band and returns to its transparent state when the laser beam subsides. The far field image is focused to a much larger volume so that it does not cause significant heating or change in optical density. The image passes through the device with a dark spot in the far field where the laser originated.