Optic fiber systems

The most important appHcation of fiber-optic laser-based communication is in long-distance telecommunications (92,93). Fiber-optic systems offer very high capacity, low cost-per-channel, light weight, small size, and immunity to crosstalk and electrical interference. 

Figure 1. Fiber optic system comprising a light source (1), optical filters (2, 3) for measurement of the concentration of a reagent solution. The fiber bundle (4), after passing the solution (16), is divided into three bundles (6-8) and light intensity is measured at three wavelengths in order to enable spectral correlation at different wavelengths.

Sampling with fiber optic sensors can be continuous if needed otherwise they can be operated discontinuously, with a lower duty cycle. These sensors could be used for laboratory-based or in situ applications. The cost of instrumentation for fiber optic systems should be 25,000 to 50,000. Sensors would need to be replaced periodically (several weeks to many months), depending upon their design. Sensors using fiber optic probes will be available within 5 years for some applications and within 10 years for some others. Sensors for pH, C02, and 02 are in development now new sensors should be capable of measuring from high concentrations down to 1 part per million for ions and organic materials. Basic research is still required for specific applications. 

Optical biosensors that respond to the absorption of light from a laser. The optical response is transmitted to a computer by a fiber-optic system. 

Fiber optic systems are more economical than their alternatives—copper wire, radio relay, and satellite. The regeneration of signals sent on copper cables is necessitated at several mile intervals, whereas tile distance on optical fibers can be. over a thousand miles by using optical amplifiers approximately every 50 miles. 

Because optical fibers are nonconducting, fiber optic systems provide excellent electrical isolation and immunity from electrical interference. Signal losses are much lower in fibers (as low as 0.20 dB/km) compared to other guided transmission media, such as twisted copper pairs, coaxial cable, and metallic waveguides. In addition, the bandwidth or information carrying capacity of fibers is far greater. When one or more optical fibers are packaged into cables, the cables are smaller and more flexible than their metallic counterparts. 

Figure 6. Fiber-optic system showing input lenses and switch-board entrance...

The modern era of telecommunications has begun to depend on bundles of optical fibers—thin, flexible tubes of glass and plastic—to send information over long-distance telephone networks. Also used in medical instruments to examine various body cavities, such as the bladder and intestines, a fiber-optics system converts electricity to pulses of light that carry the data—much more of it, in fact, than ordinary wires, which have to use pulses of electricity-... 

Germanium By-product from sphalerite Fiber-optic systems... 

Advances in instrumentation have resulted in a wide array of choices for analysts. These include instruments for specific applications with custom sample holders as well as general multiuse types. In the past 10 years, various patents have been issued for sample holders, sample supports, and a fiber optic system for dissolution.f ... 

DeThomas and VonBargen patented a NIR fiber optic system for the measurement of moisture or a constituent in a powder. Berntsson, and associates " ... 

Germanium first became important for its use in semiconductors. This application still accounts for about 15 percent of the germanium produced. But other uses of the element are now more important. About 50 percent of the germanium produced in the United States is now used in the manufacture of infrared optics and another 30 percent in fiber optic systems. 

P. Halley, Fiber Optic Systems, Wiley, New York, 1987. 

Riberio ABL, Jackson DA (1993) Low coherence fiber optic system for remote sensors illuminated by a 1.3 pm multimode laser diode. Rev Sci Instrum 64 2974—2977... 

Recently a portable real-time PCR device was demonstrated [13, 14]. This device has a miniature thermal cyclyer performing the PCR thermal cycling operation. The disposable PCR reaction chip is made of poly-dimethylsiloxane (PDMS) and glass chips, and has four reaction wells. The well size can be as small as 0.5 pL. A miniature laser-fiber optic system is developed for detecting the fluorescent signals from the four wells during the PCR process. 

The optica monochromator using a fiber optics system is used for sample characterization. 

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