Industrial Consultancy & Sponsored Research (IC&SR) , IIT Madras
Method and Apparatus for Dynamic Matching of Fiber Bragg Gratings for Dynamic Interrogation
Categories for this Invention
Technology: Fiber Bragg Gartings
Category: Photonics/Fiber Optic Sensor
Industry: Optic Cable Manufacturers
Application: Optical communications systems , Sensing Elements.
Market: The global market size of is estimated at USD 0.76 billion in 2024, and is expected to reach USD 1.16 billion by 2029, growing at a CAGR of 8.83% during the forecast period (2024-2029).
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Problem Statement
- Structural Health Monitoring (SHM) is a key requirement for capital intensive structures, which is aided by Guided-Wave Non-Destructive Evaluation (NDE) for damage identification.
- Fiber-Based Grating (FBG) sensors have been demonstrated as an excellent choice for minimally invasive guided wave measurements.
- FBG sensors have unique attributes due to their wavelength division multiplexing capability and amenability to array sensing.
- Matched FBG filter-based interrogation is an attractive approach for guided wave sensing and has been proven to be useful for SHM applications.
- Dynamic matching of the Bragg wavelength of the interrogator FBG with the sensor FBG is necessary for successful interrogation of high-frequency guided waves signals.
Technology
- An apparatus for dynamic matching of Fiber Bragg Gratings (FBG) for dynamic interrogation, wherein the apparatus comprises:
- An optical broadband source (BBS)
- An optical circulator
- A plurality of FBG sensors
- A plurality of interrogator FBGs
- The optical BBS is connected to an optical circulator to illuminate multiple FBG sensors for surface-mounted interrogation on a test sample and receive optical reflection spectra.
- The optical circulator directs broadband light from the optical BBS into multiple FBG sensors and feeds the sensor reflection spectra into a Coarse Wavelength Division Multiplexer (CWDM) filter.
- The Coarse Wavelength Division Multiplexer (CWDM) is utilized to segment optical reflection spectra from FBG sensors and connect them to corresponding interrogator FBGs mounted on voltage-controlled PZT stretchers.
- PZT stretchers apply strain and sinusoidal perturbations to interrogator FBGs, causing a proportionate change in transmitted intensity. Analog Interrogator Board converts intensity waveform changes into voltage changes using multiple APDs.
- Digitizers convert analog output waveforms into digital samples, generating DC and AC signals for calibrating interrogator FBGs.
- Control unit coordinates components for determining optimum bias voltages for BBS, APD, and PZT sensors. Digital to Analog Convertors apply optimal PZT bias voltage to PZT stretchers.
- Electromagnetic relays connect signal generators to PZT drivers for calibration and acoustic signal measurement.
Key Features / Value Proposition
- Dynamic Matching of Fiber Bragg Grating pairs for ultrasound guided wave sensing.
- Aligns interrogator’s transmission spectrum with sensor’s reflection spectrum.
- DC voltage is applied to PZT stretchers to shift the Bragg wavelength.
- Tracing APD calibration curves to APD saturation (35 kHz to 40 kHz).
- Capturing acoustics measurements.
- Auto calibration mode is available.
- Used as sensing elements in optical fiber sensors and for temperature & strain sensing etc.
- Ensures safety by detecting defects, fatigue, or corrosion in structural like buildings,dams etc.
Questions about this Technology?
Contact For Licensing
sm-marketing@imail.iitm.ac.in
ipoffice2@iitm.ac.in
Research Lab
Prof. Balaji Srinivasan
Department of Electrical Engineering
Intellectual Property
- IITM IDF Ref. 2330
- Patent No: IN 536709
Technology Readiness Level
TRL-3
Experimental proof of concept