Intrinsic fiber-optic sensors

The basic theory of optical sensors is explained. State-of-the-art fiber-optic sensors are examined. There are two types of fiber-optic sensors: extrinsic and intrinsic. With extrinsic sensors, light leaves the fiber and is blocked or reflected before going back into the fiber-optic system. Extrinsic sensors are, in general, analogous to photoelectric controls with the potential problems of being affected by dirt, dust, vibration, and alignment. Intrinsic sensors avoid these problems by changing the light while it is still inside the fiber. Five types of intrinsic sensors are described. The advantages and disadvantages of intrinsic fiber-optic sensors are given. Present and future applications of intrinsic fiber-optic sensors are described