Product Alias: Fiber Bragg Grating Interrogator, FBG Interrogator, Fiber Bragg Grating Analyzer, FBG Sensor Interrogator, Optical Sensing Interrogator, Fiber Optic Grating Interrogator, Fiber Bragg Grating Demodulator, FBG Demodulator, Fiber Optic Grating Demodulator, High-Speed FBG Interrogator, 100Hz FBG Demodulation Unit, Web-based FBG Software, Multi-channel Optical Analyzer, Modbus FBG Gateway.
This is a companion discussion topic for the original entry at https://www.ofscn.net/fbg-products/analyzer.html%EF%BC%89%E4%B8%BA
1. Physical Principles of FBG Demodulation
A Fiber Bragg Grating (FBG) interrogator (also known as a demodulator or analyzer) is a high-precision optoelectronic instrument designed to resolve and measure the wavelength shifts reflected from FBG sensors.
According to the fundamental physics of FBGs, the Bragg wavelength \lambda_B is governed by the effective refractive index of the fiber core ( n_{eff} ) and the spatial period of the grating ( \Lambda ), expressed by the Bragg equation:
\lambda_B = 2 n_{eff} \Lambda
When external physical perturbations (such as temperature shifts, mechanical strain, or pressure changes) act on the FBG, they alter both the physical period \Lambda (via thermal expansion or mechanical strain) and the refractive index n_{eff} (via the thermo-optic or photo-elastic effect). This shifts the reflected Bragg wavelength by \Delta \lambda_B . The primary task of an FBG interrogator is to sweep or analyze the optical spectrum with sub-picometer resolution to track these dynamic or static wavelength displacements.
2. Key Technical Specifications for FBG Interrogators
When selecting or evaluating industrial-grade FBG demodulation units, engineers focus on several crucial parameters:
- Wavelength Range: Commonly configured around the optical fiber’s minimal-loss C-band (approx. 1525\ \text{nm} to 1565\ \text{nm} ) to allow long-distance transmission without severe signal attenuation.
- Resolution: Often specified at 1\ \text{pm} or 0.1\ \text{pm} , which directly dictates the smallest detectable strain (approximately 1\ \mu\varepsilon ) or temperature change (approximately 0.1\ ^\circ\text{C} ) the system can resolve.
- Refresh Rate (Sampling Frequency): High-speed dynamic structural monitoring (e.g., aerospace, vibration analysis) requires high refresh rates ( 50\ \text{Hz} to 100\ \text{Hz} or higher), whereas static environmental monitoring (e.g., dam or soil displacement) can operate at lower frequencies ( 1\ \text{Hz} to 10\ \text{Hz} ).
- Multiplexing Capability: Multi-port / multi-channel architectures enable parallel acquisition from multiple fiber channels, with each channel accommodating dozens of cascaded FBG sensors in series.
3. OFSCN® Fiber Bragg Grating Interrogator Specifications
Designed for robust industrial deployment, the OFSCN® Fiber Bragg Grating Interrogator provides high-speed sampling, multi-channel scalability, and industrial-grade communication protocols.
Technical Parameters:
- Wavelength Range: Standard configuration of 1525\ \text{nm} to 1565\ \text{nm} , or 1528\ \text{nm} to 1568\ \text{nm} (customizable).
- Channel Configurations: Available in 4, 8, 16, or 32 channels (customizable to meet complex spatial sensor networks).
- Sampling Frequency: Refresh rates of 10\ \text{Hz} , 50\ \text{Hz} , or 100\ \text{Hz} are optional. Operators can lower the operating sampling rate down to 1\ \text{Hz} dynamically via software settings.
- Wavelength Resolution: Default 1\ \text{pm} or ultra-high precision 0.1\ \text{pm} (customizable).
- Software & Integration: Operates on a default Browser/Server (B/S) architecture, with full support for Client/Server (C/S) architecture. It supports seamless system integration with third-party networks and industrial PLCs through TCP, UDP, and Modbus protocols.
Product Visuals:
Figure 1: OFSCN® Fiber Bragg Grating Interrogator 8-Channel Model
Figure 2: OFSCN® Fiber Bragg Grating Interrogator 32-Channel Model
Additional System Integration Resources
