Fiber optics multiplexed

The use of fiber optics and fiber-optic multiplexing can increase the number of analysis points, and hence can reduce the overall costs related to a single analyzer. This approach has been used successfully with NIR instrumentation, where typically up to 8 points can be handled. As noted earlier, the use of fiber-optics with mid-IR Fourier transform instruments has been limited. Although in the past commercial multiplexers have been available for mid-IR fiber systems, their use has been minimal. 

The advanced control room uses fiber optics, microprocessors, and digital monitoring and control. This includes self-testing, automatic calibration, user interactive from panels, full multiplex, standardization of the man-machine interface, common circuit cards, and wide-range flux monitors to eliminate range switching on startup. 

King K.D., Vanniere J.M., LeBlanc J.L., Bullock K.E., Anderson G.P., Automated fiber optic biosensor for multiplexed immunoassays, Environ. Sci. Technol. 2000 34 2845-2850. 

Multiplexing, in fiber-optic smart structure systems, 11 147... 

The speed of information transfer can be increased by switching from twisted pair cables to coaxial or fiber optics, however, these types of cables add to the installation costs. In the future, communications between sensors and multiplex boxes and the rest of the system may use a combination of technologies including traditional means such as twisted wire and coaxial and non-traditional methods such as infrared or radio wave. 

Both PDA and CCD fiber-optic spectrophotometers may be combined with a fiber switch or multiplexer to access multiple probes or cells in a sequential fashion. Multiplexers are available to select from among 2, 6, 9, or even more fibers/probes. 

Rapid (near real time) Multicomponent capability High precision Can be on-line (no sampling) Can be remote (with fiber optics) Can multiplex multiple sample points Little or no sample preparation Nondestructive Indirect (secondary method) Multicomponent capability (interferences) Large investment (time, money) Steep learning curve Typically not a trace level technology... 

Song, L., Ahn, S., and Walt, D. R. (2006). Fiber-optic microsphere-based arrays for multiplexed biological warfare agent detection. Anal. Chem. 78,1023-1033. 

S.2.2.2 ICLS Example 2 This example discusses the determination of sodium hydroxide (caustic) concentration in an aqueous sample containing sodium hydroxide and a salt using NIR spearoscopy. An example of this problem in a chemical process occurs in process scrubbers where CO, is converted to Na,CO and H,S is converted to Na,S in the presence of caustic. Although caustic and salts have no distinct bands in the NIR, it has been demonstrated that they perturb the shape of the water bands (Watson and Baughman, 1984 Phelan et al., 1989)-Near-infrared spectroscopy is therefore a viable measurement technique. This method also has ad tages as an analytical technique for process analysis because of the stability of the instrumentation and the ability to use fiber-optic probes to multiplex tlie interferometers and Icx ate them rcm< >tely from the processes. 

In general, fiber-optic sensors provide numerous advantages over conventional sensors, which include immunity to electromagnetic interference, small and compact size, remote sensing, ability to be multiplexed, and the ability to be embedded into various solid and flexible structures, including textiles and fabrics [15]. 

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