METHOD AND DEVICES FOR TIME DOMAIN DEMULTIPLEXING OF SERIAL FIBER BRAGG GRANTING SENSOR ARRAYS

• Main Authors: SMITH, PETER W.E, COOPER, DAVID J.F
• Format: Patent
• Language: English; French
• Published: 03.10.2002
• Edition: 7
• Subjects: ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVEREDIN A SINGLE OTHER SUBCLASS; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT; MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC ORINFRASONIC WAVES; MEASURING; MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER,MECHANICAL EFFICIENCY, OR FLUID PRESSURE; MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION,OR SHOCK; MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR; MEASURING QUANTITY OF HEAT; MEASURING TEMPERATURE; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS; TARIFF METERING APPARATUS; TESTING; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR

The present invention provides a method and devices for time division multiplexing of a fiber optic serial Bragg grating sensor array containing more than one Bragg grating. The device provides a pulse read-out system that allows for a reduction in system noise and an increase in sensor resolution and flexibility. In one aspect the optical signals reflected from the Bragg grating sensor array are gated by an electronically controlled optical modulator before any wavelength measurement is performed to determine the sensor information. This offers significant advantages since the sensor information is encoded into the wavelength of the optical signal and not its intensity. Therefore the sensor signal information is not distorted by the gating. Since the gating or switching of the optical modulator is performed on the optical signal, the speed of the electronic processing needs only to be performed at the speed of variation o f the sensor information and the choice of methods of wavelength measurement is no t influenced by the gating action. The device may include one or more optical amplifiers that provide the ability to demultiplex the reflected signals electronically.