Optical fibre, coatings

Wire and cable insulation and jacketing, telecommunication wires and cables, optical fibre coating, extruded coatings... 

The General Principle of Selecting Polymers for Polymer Optical Fibre Coating... 

Most dyes, including sulfonated azo dyes, are nonvolatile or thermally unstable, and therefore are not amenable to GC or gas-phase ionisation processes. Therefore, GC-MS techniques cannot be used. GC-MS and TGA were applied for the identification of acrylated polyurethanes in coatings on optical fibres [295]. Although GC-MS is not suited for the analysis of polymers, the technique can be used for the study of the products of pyrolysis in air, e.g. related to smoke behaviour of CPVC/ABS and PVC/ABS blends [263],... 

So the function of special optical fibres for sensing is to produce a sensitive response to changes in the fibre surroundings. Such requirements on optical hardware as durability to the analyte, transparency (i.e. minimum optical losses) in a wide spectral range and common availability should be pointed out. Related to the these requirements, the choice of the fibre material as well as of the fibre coating and fibre structure belong to fundamental tasks in the design of fibre-optic sensors. 

Walsh J.E., MacCraith B.D., Meany M., Vos J.G., Regan F., Lancia A., Artjushenko S., Sensing of chlorinated hydrocarbons and pesticides in water using polymer coated mid-infrared optical fibres, Analyst, 1996 121 789-792. 

The fabrication and characterization of a fiber optic pH sensor based on evanescent wave absorption was presented by Lee63. The unclad portion of a multi-mode optical fibre was coated with the sol-gel doped with pH sensitive dye. The sensitivity of the device increased when the multiple sol-gel coatings were used in the sensing region. The dynamic range and the temporal response of the sensor were investigated for two different dyes -bromocresol purple and bromocresol green. 

The nonlinear optical and dielectric properties of polymers find increasing use in devices, such as cladding and coatings for optical fibres, piezoelectric and optical fibre sensors, frequency doublers, and thin films for integrated optics applications. It is therefore important to understand the dielectric, optical and mechanical response of polymeric materials to optimize their usage. The parameters that are important to evaluate these properties of polymers are their dipole moment polarizability a, hyperpolarizabilities 0... 

PS2 activity measurements were done with an oxygen sensor consisting of a polymer optical fibre (POF) coated with an oxygen-sensitive foil (Presens, Regensburg, Germany) as specified in [Nowaczyk et al., in this book]. 

Coating formulations (lacquers) are clear, transparent, low-viscosity, solvent-free liquids that are stable with a shelf life of several months and are suitable for optical applications ranging from the ophthalmic to the optical fibre market. As an example of the former, Figure 4.15 shows a plate half coated with a layer of ABRASIL coating material only a few micrometres thick with the scratch traces from steel wool being observed on the uncoated half.18... 

Figure 7.2 Hybrid sol-gel coatings are ideally suited to protect optical fibres.

Figure 7.3 Cracks appear in the coating of optical fibres if the organic polymer content is reduced below a certain threshold. (Reproduced from ref. 4, with permission.)...

It is used in windows, windscreens, sun visions and in air crafts, It is also used in optical fibres, contact lens, lighting fixtures, biological specimen preservation, dentures, presentation articles, automobile surface coatings, etc. 

One of such unique coatings is Diamond Like Carbon (DLC). The conventional synthesis of synthetic diamonds requires extremely high temperatures and pressures. By PECVD, Diamond Like Carbon is created under mild conditions by the decomposition of methane in H2/CH4 mixture. The applications of DLC are numerous coatings for cutting tools, optical fibres, electronic devices for reading magnetic tapes, or even protective coatings in chemical reactors. 

Fig. 19.8. SEM image of an imprinted polymer-coated tapered 400 pm optical fibre at a magnification of 60 x. ...

Fig. 19.10. Prototype of a lead ion measuring optrode system. Key to drawing (A) Ar ion laser (B) dichroic mirror (C) mirror (D) lens (E) fibre mount (F) optical fibre core (G) fibre cladding (H) templated polymer coating (I) sample (J) monochromator (K) detector (L) A/D converter (M) computer.

Luminescence probes can be made by employing the polymer as a coating for an optical fibre. The polymer coating can be directly applied to the fibre as with the PMP sensor above, it can be bonded to a vinyl-silanised fibre surface or it can be implanted as a fine powder in a sol-gel coating. The fibre sensor can be addressed in a variety of ways [34], of which the simplest is to use a bifurcated fibre. In this configuration the sensor is attached to the common leg and the detector and source are attached to the bifurcated legs. This configuration is illustrated in Fig. 19.12. 

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