Arrangement including a plurality of optical fiber bragg grating sensors and method for determining measured values in such arrangement

• US 6,765,194 B2
• Filed: 03/22/2001
• Issued: 07/20/2004
• Est. Priority Date: 03/23/2000
• Status: Expired due to Term

• Current Assignee: Airbus Operations GmbH (Airbus SE)
• Original Assignee: Daimler Chrysler Company LLC (Stellantis NV)
• Inventors: Trutzel, Michael, Holz, Michael
• Primary Examiner(s): Sugarman, Scott J.
• Assistant Examiner(s): HANIG, RICHARD E
• Application Number:
  US09/814,628
• Publication Number:
  US 20010048071A1
• Time in Patent Office: 1,216 Days
• Field of Search: 250/227.12, 250/227.18, 250/227.19, 385/37, 385/35.5, 356/32
• US Class Current: 250/227.12
• CPC Class Codes: G01D 5/35383 using multiple sensor devices using multiplexing techniques
• CPC Class Codes: G01L 1/246 using integrated gratings, e.g. Bragg gratings
• CPC Class Codes: G01L 11/025 using a pressure-sensitive optical fibre
• CPC Class Codes: G01M 11/083 by using an optical fiber in contact with the device under test [DUT]
• CPC Class Codes: G01M 5/0016 of aircraft wings or blades
• CPC Class Codes: G01M 5/0041 by determining deflection or stress
• CPC Class Codes: G01M 5/0091 by using electromagnetic excitation or detection

Abstract

An arrangement for determining measured values, in particular measured pressure values, strain values, or temperature value, using a plurality of optical fiber Bragg grating sensors. The optical fiber Bragg grating sensors are combined to form various arrays of optical fiber Bragg grating sensors that are arranged one behind the other, are connected by fiber optics, and exhibit different frequency selectivities. Delay elements are assigned to these arrays. The Bragg grating sensors receive a uniform query signal representing a time-differentiated, frequency-selective light. The frequency-selective Bragg grating sensors of the various arrays generate partial signals. The partial signals, separated temporally from one another by the delay elements, form a sequence of partial signals. From the knowledge of the propagation delays of the signals and from the knowledge of the frequency information of the query signal, the particular intended measured value is able to be related to a specific Bragg grating sensor of a specific array, thereby enabling the measured value to be allocated to the location of this Bragg grating sensor.

Claims

1. A method for determining measured values in an arrangement including a plurality of optical fiber Bragg grating sensors, the method comprising:

disposing the plurality of optical fiber Bragg grating sensors so as to form at least one sensor array, each of the respective optical fiber Bragg grating sensors in each of the at least one sensor array being arranged one behind the other, being connected by fiber optics, and exhibiting a different respective frequency selectivity;

providing at least one respective delay element in at least one of the at least one sensor array;

providing a query signal of temporally differentiated, frequency-selective narrow band light of variable center wavelength;

receiving the query signal using the plurality of optical fiber Bragg grating sensors; and

evaluating a response signal so as to assign respective individual partial signals of the response signal to one or more of the plurality of optical fiber Bragg grating sensors based on respective frequencies of the individual partial signals and based on respective propagation delays of the individual partial signals, the respective propagation delays being substantially determined by the at least one respective delay element.

2. The method as recited in claim 1 wherein a respective delay time of each of the at least one respective delay element is selectively chosen.

3. The method as recited in claim 2 wherein the respective delay time of each at least one respective delay element is variably selected and satisfies

4. The method as recited in claim 2 wherein the choosing of each respective delay time selection is performed using a control unit.

5. The method as recited in claim 1 wherein the arrangement is operated in a transmission mode.

6. The method as recited in claim 1 wherein the arrangement is operated in a reflection mode.

7. The method as recited in claim 1 wherein the at least one array includes a first and a second array disposed serially with respect to each other.

8. The method as recited in claim 1 wherein the at least one array includes a first and a second array disposed in parallel with respect to each other.

9. The method as recited in claim 1 wherein the at least one array includes includes a plurality of arrays disposed serially in part and in parallel in part with respect one another.

10. An arrangement for determining measured values, the arrangement comprising:

a plurality of optical fiber Bragg grating sensors disposed in at least one sensor array, each of the respective optical fiber Bragg grating sensors in each of the at least one sensor array being arranged one behind the other, being connected by fiber optics and exhibiting a different respective frequency selectivity, wherein the plurality of optical fiber Bragg grating sensors are configured to receive a query signal of temporally differentiated, frequency-selective narrow band light of variable center wavelength;

at least one respective delay element associated with at least one of the at least one sensor array;

a light source configured to provide the temporally differentiated, frequency-selective narrow band light of variable center wavelength; and

an evaluation unit configured to evaluate a response signal so as to assign respective individual partial signals of the response signal to one or more of the plurality of optical fiber Bragg grating sensors based on respective frequencies of the individual partial signals and based on respective propagation delays of the individual partial signals, the respective propagation delays being substantially determined by the at least one respective delay element.

11. The arrangement) as recited in claim 10 wherein the light source includes a pulsed, spectrally tunable laser, and further comprising

a control unit for controlling the light source temporally as well as spectrally.

12. The arrangement as recited in claim 10 wherein the light source includes a pulsed, spectrally tunable laser, and further comprising:

a control unit for controlling the light source temporally as well as spectrally; and

a modulator assigned to the control unit, the modulator having a signal output that is triggered by the control unit.

13. The arrangement as recited in claim 12 further comprising:

an integrator; and

a ring interferometer for generating a trigger signal using the control unit, the trigger signal for temporally controlling the integrator, the light source, the modulator, and a signal evaluation in the control unit.

14. The arrangement as recited in claim 10 further comprising:

a control unit for controlling the light source temporally as well as spectrally; and

an integrator, the integrator being triggered by the control unit so as to sum the response signal within preset timing windows in a time-separated fashion.