Multi-type fiber bragg grating sensor system

• US 20030141440A1
• Filed: 03/27/2002
• Published: 07/31/2003
• Est. Priority Date: 01/28/2002
• Status: Abandoned Application

• Current Assignee: ICES Co., Ltd.
• Original Assignee: ICES Co., Ltd.
• Inventors: Kim, Ki-Soo, Kim, Jong-Woo, Chung, Chul
• Application Number:
  US10/112,328
• Publication Number:
  US 20030141440A1
• Time in Patent Office: Days
• US Class Current: 250/227.21
• CPC Class Codes: G01B 11/165 by means of a grating deformed by the object
• CPC Class Codes: G01B 11/18 using photoelastic elements
• 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

Abstract

A multi-type Fiber Bragg Grating Sensor System adapted to use on inclined chirped grating filter and to discharge light at a predetermined period of interval, enabling to accurately detect at one time wavelength variation amount of light signals reflected from the multiple FBG sensors, the system comprising: a light emitting diode driving unit for driving a light emitting diode in response to a timing signal produced therein to prompt the light emitting diode to repeatedly emit light signals; multiple FBG sensors for receiving the light signals emitted from the light emitting diode via a light coupler to reflect the light which changes its center wavelength according to externally-applied physical properties changes; an inclined chirped grating filter for allowing the light signals respectively reflected from each FBG sensors to pass the different amount of luminous intensity according to the center wavelength change; first detector for detecting the luminous intensity of each light signal having passed the inclined chirped grating filter; second detector for detecting luminous intensity of each light signal reflected from the FBG sensor; divider for dividing the luminous intensity detected by the first detector by the luminous intensity detected by the second detector; and a controller for storing a luminous intensity variation rate (n) currently input from the divider and comparing with a variation rate (n−1) priorly input to obtain a value of wavelength change based on the difference between them and to calculate physical properties variations applied to each FBG sensor in response to the wavelength change.

Claims

1. A multi-type Fiber Bragg Grating (FBG) sensor system, the system comprising:

a light emitting diode driving unit for driving a light emitting diode in response to a timing signal produced therein to prompt the light emitting diode to repeatedly emit light signals;

multiple FBG sensors for receiving the light signals emitted from the light emitting diode via a light coupler to reflect the light which changes its center wavelength according to externally-applied physical properties changes;

an inclined chirped grating filter for allowing the light signals respectively reflected from each FBG sensors to pass the different amount of luminous intensity according to the center wavelength change;

first detecting means for detecting the luminous intensity of each light signal having passed the inclined chirped grating filter;

second detecting means for detecting luminous intensity of each light signal reflected from the FBG sensor;

divider for dividing the luminous intensity detected by the first detecting means by the luminous intensity detected by the second detecting means; and

a controller for storing a luminous intensity variation rate (n) currently input from the divider and comparing with a variation rate (n−

1) priorly input to obtain a value of wavelength change based on the difference between them and to calculate physical properties variations applied to each FBG sensor in response to the wavelength change.

2. The system as defined in claim 1, wherein the multiplicity of FBG sensors are arranged in series in a single fiber each at a predetermined distance with different center wavelengths.

3. The system as defined in claim 1, wherein the multiple FBG sensors are arranged in parallel in different optical fiber with different length from the connector and each has same wavelength.

4. The system as defined in claim 1, wherein a timing signal created from the light emitting diode driving unit is a pulse signal having a predetermined period of time.

5. The system as defined in claim 1, wherein the timing signal created from the light emitting diode driving unit is a Pseudo Random Binary Sequence signal.

6. The system as defined in claim 1 further comprising an indicator for indicating physical properties change amount calculated from the controller.