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. 21, 1993
Filed:
Jan. 15, 1991
Xiaohui Ning, N. Providence, RI (US);
American Optical Corporation, Southbridge, MA (US);
Abstract
A laser discrimination filter based on temporal coherence is presented. This filter comprises a multilayer device with 'thick' layers such that the optical thickness of each layer is greater than the coherence length of the ambient light, but still much smaller than the coherence length of the laser light of interest. Thus, the spectral response of the device of this invention becomes dependent on the degree of temporal coherence of the incident light. If white light strikes the filter, multi-beam interference will not occur because of its short coherence length. The device acts like a stack of partially reflecting mirrors. If the laser light strikes the filter, multi-beam interference will still take place because of the long coherence length of the laser light. This causes the device to have different transmitting characteristics for laser light and white light. Therefore, this device functions as a laser discrimination device.