Plastic clads

Figure 12.8. Transmission characteristics of some commonly used optical fibers, (a) glass fiber (b) gradient-index fiber (c) plastic-clad silica fiber (d) plastic fiber. (Reproduced with permission from the Ealing Corporation.)...

The wavelength and angle dependences of the depth of penetration, d, were given earlier (Equation (3.22)), and this principle is used in the MIR for the sampling technique of ATR spectroscopy. Figure 3.13(c) illustrated this, and, for typical refractive indices of fibre core and sample of 2.5 and 1.5, respectively, and an angle of incidence of 45°, the depth of penetration of the evanescent wave is about 0.152. The effect of the evanescent wave on fibre-optic spectroscopy may be illustrated by the example of plastic-clad silica (PCS) fibre optics for remote spectroscopy in the NIR spectral region, as discussed below. 

Guidance notes for the construction of reinforced plastics cladding panels (British Plastics Federation 287/i (1981))... 

Zetabond Plastic clad metal for fiber optic cables Dow Europe... 

The major elements required for fiber-optics transmission include long flexible fibers made of transparent materials such as glass, plastic, or plastic-clad silica a light-transmittal source such as a laser of light-emitting diode (LED) cables or rods lined with a reflective core medium to direct light and a receiver to capture the signal. Many systems... 

PCS Personal Communications Services personal communications system plastic-clad... 

There are several schemes for measuring temperature. One scheme is based on the change in luminescence of a phosphor with temperature. The phosphor powder is attached to the distal end of a plastic clad silica fiber. A pulse of UV light is sent through the fiber and excites the phosphor. The visible luminescence is returned through the same fiber, and its decay time is measured. The decay time is dependent on temperature, and its measurement is translated into a temperature reading. The accuracy is better than 0.1 °C near room temperature. 

Use of precoated, in-factory or in situ plastic clads and simple or complex plastic laminates (e.g. fibrereinforced plastic laminate, polypropylene sheet with glass fibre cloth, etc.), for the fabrication of suitably designed corrosion-resistant structures should be evaluated. 

Use of precoated and plastic-clad metals may be considered for production of equipment cabinets. 

Optical fibers were provided by NRL and all fiber tapering was conducted at the laboratory in Washington, DC. Fibers were made from step-index plastic clad silica optical fiber (200 m core, Quartz et Silica, Quartz Products) with a black plastic ferrule on the proximal end. The proximal face of the fiber is polished after insertion into the ferrule. The total length of the fiber is approximately 1 meter with only 10 centimeters of the entire fiber being used for assay purposes. At the distal end of the fiber (last 12 cm), the cladding was stripped with a razor blade and the fiber core was tapered by computer-controlled immersion into hydrofluoric acid. 

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