Research/Patents/US 5360235
US 5360235

SECRET OPTICAL MARKING

Assignee

Filed

Nov 1, 1969

Granted

Nov 1, 1994

Location

Abstract

An optical marking system in which objects are coated with materials for purposes of applying secretly coded marks on the objects. The coating materials are transparent in daylight and have the property of absorbing ultraviolet light. When such materials are applied to a portion of the surface of an object which is a good ultraviolet reflector, only the uncoated portion reflects ultraviolet. Thus, the marked object is therefore seen as having the coated portion blocked-out when viewed through a device which filters out all but ultraviolet wavelengths but appears to be unmarked when observed without the viewing device. Similar coding of objects may be achieved by appropriately selected paints, papers and other materials.

Source: Google Patents

35 USC §181 Secrecy Order

Imposed

Jan 15, 1982

Rescinded

Feb 22, 1994

Duration

12 years, 1 month

Technology Domains

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Back to patent indexSource: USPTO 35 USC §181 secrecy order records