FIBER GRATING SENSOR SYSTEM FOR MEASURING KEY PARAMETERS DURING HIGH SPEED

• US 20150268096A1
• Filed: 10/23/2012
• Published: 09/24/2015
• Est. Priority Date: 10/23/2012
• Status: Active Grant

• Current Assignee: Udd, Eric
• Original Assignee: Udd, Eric
• Inventors: Udd, Eric
• Granted Patent: US 9,417,127 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01J 2003/102 Plural sources
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/1895 using fiber Bragg gratings or gratings integrated in a waveguide
• CPC Class Codes: G01K 11/3206 at discrete locations in the fibre, e.g. using Bragg scattering
• 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

Abstract

A fiber grating sensor system is used to measure key parameters that include pressure, strain and temperature at specific locations and at high speed. The system relies on spectral properties associated with the fiber grating sensors, the light source and the optical detection system to provide these capabilities. The system has been successfully applied to measurement of pressures up to 1,200,000 psi and by increasing the spectral width of the light source extensions of pressure measurements to 4,000,000 psi and higher are possible. Temperature change measurements have been made of 400 degrees C. over a period of 25 micro-seconds limited by the physical response of the fiber sensors and the output detector bandwidth both of which can be greatly improved by reducing fiber sizes and with improved detectors. Novel methods have been devised to lower cost and enable measurements with spatial location, speed and accuracy that have been very difficult or not yet achieved.

Claims

1. A high speed fiber grating sensor system comprising:

a first light source with a predefined spectral shape which generates a first light beam;

and a first optical coupler which captures said first light beam in first input optical fiber and directs it via a second optical fiber to a first fiber grating sensor with a predefined spectral shape, a second light beam which is a portion of said first light beam reflects off said first fiber grating sensor and is directed back toward first optical coupler and directed via a third optical fiber to a first optical detector with a predefined spectral response, the output from said first optical detector being directed toward a first electrical signal storage device.

2. A high speed fiber grating sensor system as in claim 1 with a second optical coupler which captures said second light beam and directs a first portion of said second light beam to an output spectrometer and second portion of said second light beam to said first optical detector.

3. A high speed fiber grating sensor system as in claim 1 with said first light source being a broad band light source with at least one rapidly falling or rising spectral edge or peak.

4. A high speed fiber grating sensor system as in claim 1 with said fiber grating being a chirped fiber grating with one or more low reflectivity spectral regions.

5. A high speed fiber grating sensor system as in claim 1 where said first optical detector is comprised of a first wavelength division multiplexed unit defining specific spectral regions and each spectral region is associated with a high speed optical output detector.

6. A high speed fiber grating sensor system comprised of;

a first light source with a defined spectral output; and

a first optical filter coupled to the first light source to shape spectral output of first light beam from said first light source; and

a first optical coupler to capture the first light beam after it passes through first optical filter with a first input port; and

a first fiber grating sensor connected to a second port of said first optical coupler; and

first reflected light beam from said first fiber grating sensor being captured by said second port of said first coupler and directed by third output port of said first coupler to a first output optical detector.

7. A high speed fiber grating sensor system as in claim 6 where electrical output from said first optical detector is connected to an electrical digital signal recorder.

8. A high speed fiber grating sensor system as in claim 6 where said light source consists of multiple light sources with different spectral content that have been wavelength division multiplexed.

9. A high speed fiber grating sensor system as in claim 6 where said first fiber grating sensor consists of multiple fiber gratings.

10. A high speed fiber grating sensor system as in claim 6 where said first fiber grating sensor consists of multiple chirped fiber gratings.

11. A high speed fiber grating sensor system as in claim 6 where said first fiber grating sensor is a chirped grating with multiple regions of low reflectivity.

12. A high speed fiber grating sensor system as in claim 6 where said first fiber grating is used to measure and localize pressure and temperature of a blast wave.

13. A high speed fiber grating sensor system as in claim 6 where said first fiber grating sensor is used to measure localize a rapidly varying temperature variation.

14. A high speed fiber grating sensor system as in claim 6 where said first fiber grating sensor is used to measure and localize a rapid strain variation.

15. A high speed fiber grating sensor system comprising:

a. a first light source means with a spectral profile with rapidly varying edges to generate a first light beam and

b. a first optical coupler means to receive said first light beam and direct it to first fiber grating sensor having a predefined spectral profile and

c. first reflected beam from said first coupler means being directed via first optical coupler means to a first optical detector means and

d. output from first optical detector means being directed to an electrical signal storage means

16. A high speed fiber grating sensor system as in claim 15 where an optical spectral filter is placed between the first optical light source means and the first optical coupler means.

17. A high speed fiber grating sensor system as in claim 15 where an optical spectral filter is placed between the first optical coupler means and the first output optical detector means.

18. A high speed fiber grating sensor system as in claim 15 where the first fiber grating sensor means consists on an array of fiber gratings.

19. A high speed fiber grating sensor system as in claim 15 where the first fiber grating sensor means consists of an array of chirped fiber gratings.

20. A high speed fiber grating sensor system as in claim 15 where said first optical detector means consists of wavelength division multiplexing means to distinctly divide the spectra of the output light signal onto multiple output detectors