An apparatus and method for detecting watermark and security thread in a currency note. Optical sensing circuits positioned from the surface of the currency note rely upon the transmissive and reflective characteristics of the security features and the note itself to determine the authenticity of the...http://www.google.com/patents/US6104036?utm_source=gb-gplus-sharePatent US6104036 - Apparatus and method for detecting a security feature in a currency note
