Method and device for time domain demultiplexing of serial fiber Bragg grating sensor arrays
First Claim
1. An optical fiber serial Bragg grating sensor device, comprising:
- a) a light source adapted to produce optical pulses;
b) an optical fiber network including an optical fiber optically coupled to said light source, the optical fiber including a Bragg sensor array having at least two spaced apart Bragg gratings; and
c) an optical transmission element connected to a section of said optical fiber network adapted to receive optical pulses reflected from said at least two Bragg gratings, a wavelength detection means optically coupled to said optical transmission element, switch means connected to said optical transmission element for switching said optical transmission element between an attenuating state in which said optical transmission element attenuates light and a transmission state in which light is transmitted through said optical transmission element to said wavelength detection means, said switch means being activated at selectively adjustable times after production of said optical pulses.
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Abstract
The present invention provides a method and device for to implement 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. The optical signals reflected from the Bragg grating sensors 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 between transmission and attenuating states is performed on the optical signal, the speed of the electronic processing needs only to be performed at the speed of variation of the sensor information and the choice of methods of wavelength measurement is not influenced by the gating action.
57 Citations
29 Claims
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1. An optical fiber serial Bragg grating sensor device, comprising:
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a) a light source adapted to produce optical pulses;
b) an optical fiber network including an optical fiber optically coupled to said light source, the optical fiber including a Bragg sensor array having at least two spaced apart Bragg gratings; and
c) an optical transmission element connected to a section of said optical fiber network adapted to receive optical pulses reflected from said at least two Bragg gratings, a wavelength detection means optically coupled to said optical transmission element, switch means connected to said optical transmission element for switching said optical transmission element between an attenuating state in which said optical transmission element attenuates light and a transmission state in which light is transmitted through said optical transmission element to said wavelength detection means, said switch means being activated at selectively adjustable times after production of said optical pulses. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 24, 25)
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16. A device for time domain demultiplexing serial optical fiber Bragg grating sensor networks, the network including a light source adapted to produce optical pulses connected to an optical fiber network with the optical fiber network including a sensor array having at plurality of spaced Bragg gratings, comprising:
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an optical transmission element connected to a section of said optical fiber network adapted to receive optical pulses reflected from said at least two Bragg gratings, switch means connected to said optical transmission element for switching said optical transmission element between a transmission state in which said optical transmission element transmits light therethrough and an attenuating state in which said optical transmission element attenuates light, said switch means being activated at selectively adjustable times after production of said optical pulses; and
wavelength detection means connected to said optical transmission element. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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26. A method for time domain demultiplexing a serial fiber Bragg grating sensor network, the sensor network including an optical fiber having at least two spaced Bragg gratings and a light source for producing light pulses that propagate along said sensor network and are incident on said at least two Bragg gratings, comprising:
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directing optical pulses reflected by said at least two Bragg gratings to an optical transmission element;
spectrally analyzing optical pulses reflected from a selected Bragg grating by switching said optical transmission element to a state of transmission at effective periods of time after preselected optical pulses are produced, said periods of time being equal to a transit time of said optical pulses from a light source to said selected Bragg grating and to said optical transmission element; and
maintaining said optical transmission element in the state of transmission for an effective period of time to permit light pulses to be transmitted through said optical transmission element to a wavelength detection means and thereafter switching said optical transmission element to a state of attenuation to block optical pulses reflected from all other Bragg gratings. - View Dependent Claims (27, 28, 29)
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Specification