tect the op- tical performance. Two common types of fiber optic cable This method measures the phase delay for different construction are shown in Fig. 6.1-22. Common for all wavelengths. The source is an incoherent high-pressure cable types is that the individual fibers are coated with some kind of organic material, examples of which include the following [16]: Polydimethyl siloxane Silicone oils Extrudates Acrylates CYLINDRICAL CONICAL For ease of manufacturing and to prevent the glass FERRULE FERRULE surface from being scratched the coating is applied during the drawing process. Often, the first coating is not EXPANDED-BEAM FIBER FIBER COLLIMATING/FOCUSING ELEMENT Fig. 6.1-26 (a) Example of two popular alignment mechanisms used in fiber optic connectors, (b) Schematic representation of a typical expanded-beam type connector. Reprinted from Ref. [23], p. 316 (a) and p. 318 (b), courtesy of Academic Fig. 6.1-27 FC connectors and adaptors. Reprinted from Press. Ref. [24], p. 16, courtesy of Molex Fiber Optics, Inc. UNAPICh 0.1 Optical Tiber, cable and connectors Fig. 6.1-28 (a, b) Spring latches. Reprinted from Ref. [24], p. 24 (a), and p. 34 (b), courtesy of Molex Fiber Optics, Inc. sufficient to protect the fiber and additional coatings are used, which are commonly referred to as buffering. The buffered fiber is then embedded in various strength members and additional protective jackets. These additional layers have as their primary goals to protect the fibers from water, rodents, and tempera- ture fluctuations and to reduce stress in the fiber (Fig. 6.1-23). 6.1.4 Connectors Fig. 6.1-29 Duplex connectors: (a) ESCON (R), (b) FDDI, (c) FCS 6.1.4.1 Connector types duplex (fiber channel standard compliant). Reprinted from Ref. [1], p. 50, courtesy of Academic Press. It is important to be able to easily reconfigure commu- nication links for cost and performance optimization, to replace link subunits, and for relocating equipment [1]. To do this, connectors are a key component. There are 6.1.4.2 Mechanical propertie