If both parameters change at once, how is the cross-sensitivity issue resolved?
FBG sensors exhibit cross-sensitivity between temperature and strain, meaning both parameters influence the Bragg wavelength shift. To resolve this for simultaneous measurement, a common method involves using two Fiber Bragg Gratings:
- Reference FBG (Temperature Sensor): One FBG is isolated from mechanical strain, typically by packaging, so it only responds to temperature changes. This FBG acts as a dedicated OFSCN® Fiber Bragg Grating Temperature Sensor, providing the temperature-induced wavelength shift.
- Measurement FBG (Strain and Temperature Sensor): A second FBG is directly exposed to both the strain and temperature of the measured object. This is typically an OFSCN® Alloy Tube Packaged Fiber Bragg Grating Strain Sensor. Its wavelength shift will be a combination of both effects.
By subtracting the temperature-induced wavelength shift (obtained from the reference FBG) from the total wavelength shift of the measurement FBG, the pure strain-induced wavelength shift can be accurately determined.
Here is an example of an OFSCN® Alloy Tube Packaged Fiber Bragg Grating Strain Sensor:
You can find more detailed technical specifications for our strain sensors here: OFSCN® Fiber Bragg Grating Strain Sensor.