In order to guarantee an optimal performance of a FBG sensor it is necessary to use interrogation techniques through which it is possible to obtain precise evaluation of the Bragg wavelength shift, correspondent to the variation of the physical parameters. the availability of measurement systems is limited by requirements like frequency, sensor multiplexibility, resolution, sample rate and ambient conditions.
The commonly used interrogation techniques are based on five different principles, and one of them is the resort to spectrometer.
Using a spectrometer with its own signal processing electronics, adapted to the requirements for FBG signal processing the measurement rate can be increased to the limit of the opto-electronic sensors such as CDD (charged coupled devices) and photodiode line sensors, which is currently in the range of several kHz.
New spectrometer designs provide an optical resolution of up to 20…40 pm/pixel and a sensitivity beyond 1nW/pixel.
Regarding discrete pixels of the image line sensor, the resolution is limited to the pixel size. The resolution of the spectrometer can be enhanced by digital signal processing.