Optical fibers manufacturing methods

Optics. Good optical properties and low thermal resistance make poly(methyl methacrylate) polymers well suited for use as plastic optical fibers. The manufacturing methods and optical properties of the fibers have been reviewed (124) (see Fiber optics). Methods for the preparation of Fresnel lenses and a Fresnel lens film have been reported (125,126). Compositions and methods for the industrial production of cast plastic eyeglass lenses are available (127). 

Of a large number of possible fluorinated acrylates, the homopolymers and copolymers of fluoroalkyl acrylates and methacrylates are the most suitable for practical applications. They are used in the manufacture of plastic lightguides (optical fibers) resists water-, oil-, and dirt-repellent coatings and other advanced applications [14]. Several rather complex methods to prepare the a-fluoroalkyl monomers (e.g., a-phenyl fluoroacrylates, a-(trifluoromethyl) acrylic and its esters, esters of perfluoromethacrylic acid) exist and are discussed in some detail in [14]. Generally, a-fluoroacrylates polymerize more readily than corresponding nonfluorinated acrylates and methacrylates, mostly by free radical mechanism [15], Copolymerization of fluoroacrylates has been carried out in bulk, solution, or emulsion initiated with peroxides, azobisisobutyronitrile, or y-irradiation [16]. Fluoroalkyl methacrylates and acrylates also polymerize by anionic mechanism, but the polymerization rates are considerably slower than those of radical polymerization [17]. 

Each one of the previous issues can influence the performance of the processing technique and the resulting composite in a variety of ways. Insufficient cure may result in a low and a consequent creep under stress. Inadequate flow may result in high levels of porosity or large voids. Online sensor systems permit process control [19] and are a useful tool toward improved quality in composites manufacture. Dielectric techniques have achieved the greatest success as commercial in-process monitoring systems. Optical-fiber methods show promise for further development, most notably where distinct features in chemical spectra can be obtained. 

There are many potential variations in the processes used to manufacture optical fiber, but the basic premise remains essentially the same for each. This section will introduce the basics of fiber manufacturing and briefly discuss the three primary methods currently employed to support the economical production of optical fiber on a large scale. They are outside vapor deposition (OVD), vapor axial deposition (VAD), and inside vapor deposition (IVD). 

The production method up until around 2005 was the preform method (a manufacturing method where a G1 preform is created, which is then made into Gl-POF through heat-drawing) with a focus on the interfacial-gel polymerization method. However, from around 2005, we began to develop the continuous extrusion method in earnest, and by 2008 succeeded in 40-Gb transmission. This was the world s fastest transmission speed, surpassing the Gl-type silica optical fiber. 

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