Optic fiber

Applications in fiber optics, luminescent solar concentrators 

The laser action of a glass or crystal depends on the laser peak cross-section and the threshold power for lasing. The peak cross-section a is given by [116] 

Rare earth doped lasers of Nd(III), and Ho(III), and Er(III) are available and in use [117]. The threshold powers have been calculated for these ions in various glasses and are as follows. 

The threshold powers can be lowered by transferring energy from other ions. The effect of added ions on threshold power is obvious from the data given below. 

MODERN ASPECTS OF RARE EARTHS AND THEIR COMPLEXES 

FIGURE 4-1 Refractivity and core diameter ranges for three types of optic fibers, (a) Multi-mode step-index optic fiber, (b) Multi-mode gradient-index optic fiber, (c) Single model step-index optic fiber. 

Based on the basic performance of optic fiber sensors, Krohn (1986) divided optic fiber sensors into two basic classes. In the first class, the transmission of the fiber is directly affected by the physical phenomena being sensed and is referred to as an intrinsic optic fiber sensor. The second class is for optic fiber position sensors which detect position changes and are sensitive to changes in physical property. There are usually five types of sensors according to their different working principles intensity modulated, transmitting, reflective, micro bending 

Optic fiber sensors used in multiphase flows are based on the reflectivity of particles against incident light. This kind of optic fiber sensor, the so-called intensity modulated optic fiber sensor, is simple in structure, easy in operation and high in sensitivity. 

The application of optic fiber probes to the measurement of local concentration of solids and particle velocity, will be described below separately. 

FIGURE 4-2 Two different arrangements of optic fiber probes (Matsuno et al, 1983). 

The iavention of the laser ia 1958 prompted the beginning of the story of optical fiber communications. This device was capable of produciag a high iatensity, coherent beam of light which could be modulated at a high rate (see Lasers). StiU, no transmission medium of suitable clarity was available. 

Ia early telephoaes, souad (voice) waves caused a carboa microphone s resistance to vary, thus varyiag the current flowing ia a series external circuit. This d-c curreat could thea be used to regeaerate voice waves ia a receiver. Two wires were required to carry a single coaversatioa. With time, telecommunications traffic was eacoded oa a-c carriers, at first usiag ampHtude or frequeacy modulatioa, and more recently pulse code modulation. 

Kirk-Othmer Encyclopedia of Chemical Technology (4th Edition) 

The abihty of a waveguide to collect light is determined by the numerical aperture (NA) which defines the maximum angle at which light entering the fiber can be guided. 

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The experiment was carried out by a continuously working Nd YAG-laser fabricated by NEC. The laser has a maximum output of 1200 W and is controlled by handling facility with a linear axle. A stage index fiber optical waveguide with a diameter of d=1000 pm was used for the control of the beam. The focusing optics consist of a focusing lens (f=l 16 mm) and a collimation lens (f=70 mm). 

Palais J C 1992 Fiber Optic Communication 3rd edn (Englewood Cliffs, NJ Prentice Hall) Tanenbaum AS 1996 Computer Networks 3rd edn (Upper Saddle River, NJ Prentice Hall)... 

Agrawal G P 1989 Noniinear Fiber Optics, Quantum Eiectronics Principies and Appiications (New York Academic)... 

Cheo P K 1985 Fiber Optics and Optoeiectronics (Englewood Cliffs, NJ Prentice Hall)... 

AgraWal G P 1997 Fiber-Optic Communication Systems (New York Wiley-Interscience)... 

The element is not found free in nature, but occurs as orthoboric acid usually found in certain volcanic spring waters and as borates in boron and colemantie. Ulexite, another boron mineral, is interesting as it is nature s own version of "fiber optics."... 

The sample cells for molecular fluorescence are similar to those for optical molecular absorption. Remote sensing with fiber-optic probes (see Figure 10.30) also can be adapted for use with either a fluorometer or spectrofluorometer. An analyte that is fluorescent can be monitored directly. For analytes that are not fluorescent, a suitable fluorescent probe molecule can be incorporated into the tip of the fiber-optic probe. The analyte s reaction with the probe molecule leads to an increase or decrease in fluorescence. 

PCTFEin pLUORINECOMPOUNDS,ORGANIC - POLYCm.OROTRIFLUOROETTTVLENE] (Volll) Fiber optic communications... 

Fiber optics cables Fiber optic waveguides Fiber-reactive dyebath Fiber reactive dyes... 

Fibers, cotton Fibers, glass Fibers, optical... 

The market for optical fiber worldwide in 1992 was 2.8 billion corresponding to 10 million fiber kilometers (Mfk) (38). This can be broken down into the U.S. market (3.7 Mfk), the rest of North America (0.4 Mfk), northern Europe (4.1 Mfk), eastern Europe (2.6 Mfk), the Pacific Rim (2.8 Mfk), and elsewhere (0.3 Mfk). Most of the optical fiber is manufactured by only a few companies, the largest of which are AT T and Coming. Other producers include Alcatel, Eujikura, Eurakawa, Northern Telecom, Pirelli, and Sumitomo. The market for optical fibers is projected to reach 3.5 biUion by 1998. In addition, according to ElectroniCast (San Mateo, Ca.), the total market for passive optical components, optical electronics, connectors, and fiber-optic cable is predicted to increase from 1.76 billion (U.S.) in 1992 to over 4 billion in 1997, and 10 billion by 2002. 

Relatively smaller amounts of very high purity A1F. are used ia ultra low loss optical fiber—duotide glass compositions, the most common of which is ZBLAN containing tirconium, barium, lanthanum, aluminum, and sodium (see Fiber optics). High purity A1F. is also used ia the manufacture of aluminum siUcate fiber and ia ceramics for electrical resistors (see Ceramics AS electrical materials Refractory fibers). 

Mercury(II) fluoride has been used in the process for manufacture of fluoride glass (qv) for fiber optics (qv) appHcations (11) and in photochemical selective fluorination of organic substrates (12). It is available from Advance Research Chemicals, Aldrich Chemicals, Johnson/Matthey, Aesar, Cerac, Strem, and PCR in the United States. The 1993 annual consumption was less than 50 kg the price was 800—1000/kg. 

The principal uses of PCTFE plastics remain in the areas of aeronautical and space, electrical/electronics, cryogenic, chemical, and medical instmmentation industries. AppHcations include chemically resistant electrical insulation and components cryogenic seals, gaskets, valve seats (56,57) and liners instmment parts for medical and chemical equipment (58), and medical packaging fiber optic appHcations (see Fiber optics) seals for the petrochemical /oil industry and electrodes, sample containers, and column packing in analytical chemistry and equipment (59). 

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