Fibre optic sensors are used to monitor displacement, liquid level, flow, temperature and pressure, chemical composition etc. Optic fibre sensors can be devided into two types, they are:
The Active sensors: In active sensors, the quantity to be measured acts directly on the fibre and modifies the radiation passing down the fibre.
The various active sensors are:
(i) Intensity modulated sensors: These are based on the change in refractive index, temperature, absorption, etc
(ii) Phase-modulated sensors: These involve the interference between the signal and reference in the interferometer. This leads to a shift in the interference fringes ...