USA As Represented by Secretary of the Navy

Ignacio M Perez

William R Scott

Vinod S Agarwala

Som D Tyagi

Thomas Frederick Bibby, Jr

An optical fiber coupled to a high power laser carries laser energy to la-activated sound generating materials disposed at intervals along its length. The sound-generating materials are acoustically coupled to an object or objects to be monitored. Acoustic reflections from the objects modulate the periods of Bragg gratings formed in a separate core of the fiber, or in the core of a separate fiber. The modulation of a Bragg grating period is detected as a Doppler shift in an interrogation beam reflected by the grating.

Distributed fiber optic laser ultrasonic system

At least a part of a first coherent beam of monochromatic light is incident bliquely on the reflecting surface of a mirror to produce a reflected beam in a direction different from that of the first beam. An interference pattern is produced within a volume defined by the intersection of the reflected beam with the first beam. A part of an optical fiber is positioned in the volume containing the interference pattern, and a grating is photo-induced in the optical fiber by exposure of the optical fiber to the interference pattern. A desired Bragg period in the grating can be selected by tilting the mirror to change the interference pattern.

Apparatus and process for making fiber optic bragg gratings

A nondestructive method and apparatus for optical detection and monitoring corrosion in structures normally inaccessible to light and observation. An optical fiber coated with a corrosion sensitive compound is embedded in the structure. Tapped Bragg gratings of different Bragg periods are spaced along the fiber and refract a narrow bandwidth component of a broad beam light pulse transmitted through the fiber. Due to corrosion, the refracted components are reflected by the compound and their amplitudes are detected and displayed for each narrow bandwidth.

Corrosion detecting and monitoring method and apparatus

A tapped Bragg grating is used to demodulate optical signals reflected by ber optic Bragg gratings in a sensor in which the line spacings in the fiber optic Bragg gratings vary in response to a mechanical stress. A light detector, or light detector array is used to detect variation in the angular pattern of the light scattered by the tapped Bragg grating. Arrangements of mirrors, or alternatively arrangements of lenses, are used to concentrate the scattered light toward the light detectors and to enhance the angular changes in the scattered light.

Fiber optic Bragg grating demodulator and sensor incorporating same

A Josephson break junction device suitable for highly sensitive electronic detecting systems. A superconductor film such as YBa.sub.2 Al.sub.3 O.sub.7 is deposited on a substrate such as a single-crystal MgO. The film is fractured across a narrow strip by at least one indentation in the substrate juxtaposed from the strip to form a break junction. A transducer is affixed to the substrate for applying a bending movement to the substrate to regulate the distance across the gap formed at the fracture to produce a Josephson turned junction effect. Alternatively, or in addition to the transducer, a bridge of a nobel metal is applied across the gap to produce a weak-link junction.

Josephson break junction thin film device

A Josephson break junction device suitable for highly sensitive electronic detecting systems. A superconductor film such as YBa.sub.2 Cu.sub.3 O.sub.7 is deposited on a substrate such as a simple-crystal MgO. The film is fractured across a narrow strip by at least one indentation in the substrate juxtaposed from the strip to form a break junction. A transducer is affixed to the substrate for applying a bending movement to the substrate to regulate the distance across the gap formed at the fracture to produce a Josephson turned junction effect. Alternatively, or in addition to the transducer, a bridge of a novel metal is applied across the gap to produce a weak-link junction.

Growing community of inventors

Yardley, PA, United States of America

Ignacio M Perez