Michael R Nicholas

US Patent:

8578759, Nov 12, 2013

Filed:

Nov 7, 2011

Appl. No.:

13/290302

Inventors:

David C. Calvo - Alexandria VA, US
Jill P. Bingham - Norfolk VA, US
Michael Nicholas - Washington DC, US

Assignee:

The United States of America, as represented by the Secretary of the Navy - Washington DC

International Classification:

G01M 3/38

US Classification:

73 405A, 73643, 73655

Abstract:

A method and an apparatus for intrusion detection. The apparatus includes an acoustic source, a laser light source, a pressure-sensitive optical fiber including a first end and a second end. The second end is connected to the laser light source and oriented toward the acoustic source. The laser light source generates a laser pulse traveling through the pressure-sensitive optical fiber toward the acoustic source. The laser pulse includes a time-of-flight. The acoustic source generates an acoustic wave. The acoustic wave includes a plurality of evanescent wave fronts. The plurality of evanescent wave fronts, upon scattering from a non-uniform material region, radially contracts the pressure-sensitive optical fiber to alter the time-of-flight of the laser pulse along the pressure-sensitive optical fiber by increasing the fiber length.