Fibre Optic Thermometers
Properties of Optical Fibres
Dielectric opticalfibre, which is also referred to as a light guide, is composed of a rod core surrounded by a sheath as shown in Figure 6.1 . The core, which conducts the electromagnetic wave, has a refractive index, nj , while the sheath, which contains the wave within the core, has a refractive index, n2 . To ensure that the wave is contained in the core it is necessary that the condition nj n2 is satisfied. The electromagnetic waves incident on the front part of the optical fibre, within the angle cone, 2a,...