Optic temperature probe

A variety of optical alignment accessories for the launch of the excitation light into the fiber optic temperature probe, the collection of the fluorescence response, and optical filters used to isolate the excitation and fluorescence emission at the detector and in some cases at the excitation source as well. 

J. P. Dakin and D. A. Kahn, A novel fibre optic temperature probe, Opt. Quan. Electron. 9, 540 (1977). 

Fiber optic sensors are an alternative to thermocouples as embedded temperature distribution mapping sensors. As described in Section 2.2.7, McIntyre et al.104 developed two distinct fiber optic temperature probe technologies for fuel cell applications (free space probes and optical fiber probes). Both sensor technologies showed similar trends in fuel cell temperature and were also used to study transient conditions. 

One of the extraction vessels is equipped with a temperature and pressure sensor/control unit. Figure 3.10 shows the schematic diagram of a control vessel as well as a standard vessel. A fiber-optic temperature probe is built into the cap and the cover of the control vessel. The standard EPA method requires the microwave extraction system to be capable of sensing the temperature to within +2.5°C and adjusting the microwave field output power... 

Walker GW, Sundar VC, Rudzinski CM, Aetna WW (2003) Quantum-dot optical temperature probes. Appl Phys Lett 83 3555-3557... 

Equipment Single mode microwave synthesizer configured for manual peptide synthesis equipped with a fiber optic temperature probe (Discover SPS microwave-assisted peptide synthesizer, GEM Corporation) (rrr Note 1). 

A particularly difficult problem in microwave processing is the correct measurement of the reaction temperature during the irradiation phase. Classical temperature sensors (thermometers, thermocouples) will fail since they will couple with the electromagnetic field. Temperature measurement can be achieved either by means of an immersed temperature probe (fiber-optic or gas-balloon thermometer) or on the outer surface of the reaction vessels by means of a remote IR sensor. Due to the volumetric character of microwave heating, the surface temperature of the reaction vessel will not always reflect the actual temperature inside the vessel [7]. 

When metals have Raman active phonons, optical pump-probe techniques can be applied to study their coherent dynamics. Hase and coworkers observed a periodic oscillation in the reflectivity of Zn and Cd due to the coherent E2g phonons (Fig. 2.17) [56]. The amplitude of the coherent phonons of Zn decreased with raising temperature, in accordance with the photo-induced quasi-particle density n.p, which is proportional to the difference in the electronic temperature before and after the photoexcitation (Fig. 2.17). The result indicated the resonant nature of the ISRS generation of coherent phonons. Under intense (mJ/cm2) photoexcitation, the coherent Eg phonons of Zn exhibited a transient frequency shift similar to that of Bi (Fig. 2.9), which can be understood as the Fano interference [57], A transient frequency shift was aslo observed for the coherent transverse optical (TO) phonon in polycrystalline Zr film, in spite of much weaker photoexcitation [58],... 

Above the freezing point of silver, Tgq is defined in terms of a defining fixed point and the Planck radiation law, and optical pyrometers are frequently used as temperature probes. The Comite Consultatif de Thermometrie gives a thorough discussion of the different techniques for approximation of the international temperature scale of 1990 [2, 4],... 

Figure 11.15. Schematics of the optical arrangement and temperature probes for the Cr+ fluorescence lifetime-based fiber optic thermometers. F = short-pass optical filter Fa = bandpass or long-pass optical filter LD = laser diode LED = light emitting diode S = the fluorescence material used as sensing element vm = signal to modulate the output intensity of the excitation light source v/= the detected fluorescence response from the sensing element.

Fiber optic fluorescence thermometry can provide several quite flexible approaches to access the required measurement regions. The temperature probes can be... 

K. T. V. Grattan, A. W. Palmer, and Z. Zhang, Development of a high-temperature fiber-optic thermometer probe using fluorescent decay, Rev. Sci. Instrum. 62(5), 1210-1213. 

Perhaps the most studied laboratory flame is the premixed flat flame. As illustrated in the left-hand panel of Fig. 1.1, a steady flame is established above a porous burner face. Such flames are used widely in combustion laboratories, where a variety of optical and probe-based diagnostics are used to measure species and temperature profiles. Models play an essential role in assisting the interpretation of the data. In addition to the premixed flat... 

Weckhuysen and coworkers (Nijhuis et al., 2003) described equipment suitable for parallel Raman and UV-vis spectroscopic measurements. Openings on the opposite sides of a furnace allowed acquisition of Raman and UV-vis spectra through optical grade windows in a tubular quartz reactor. UV-vis spectra were recorded at 823 K. Gas-phase analysis was achieved with mass spectrometry and gas chromatography. A more advanced version of the design (Nijhuis et al., 2004) accommodates four optical fiber probes, placed at 10-mm vertical spacing along the tubular reactor. The temperature that the fibers can withstand is 973 K the reported spectra characterize samples at 823 K. 

Fig. 18 Detailed schematic of the capillary housing CH. Cl, C2 - opto/fluid connectors, AD -SMA bulk head adaptor, CAP - capillary, SH - stainless steel housing, FW - flat washer, FPl - fluid port, FI, F6 - multimode fibers, CB - copper block, OAP - optical access ports, TP - temperature probes. (Reprinted from Dhadwal et al. [2], with permission of Elsevier)...

The temperature dependences of many optical properties of the resin, e.g. fluorescence and Raman scattering (the ratio of Stokes to anti-Stokes intensities), provide an opportunity to use this as a way of monitoring temperature by comparison with a known standard material. Other systems are based on the properties of the fibre itself or a deliberately added dopant rather than the resin being probed. Table 6.4 shows the commercially available temperature probes that are based on optical phenomena and the use of fibre-optics (Fernando and Degamber, 2006). 

Table 6.4. Commercially available temperature probes that are based on optical phenomena and fibre-optics ...

Lovett s team at Pratt Whitney (Chapter 17) applied a fuel-control system in an actual aircraft engine combustor to actively control pattern factor. For this purpose, available fuel injectors were properly equipped with miniature valves to make possible spatial control of individual fuel injection sites. Optical temperature sensor probes and a traversing gas-sampling rake were integrated into a test rig to quantify the spatial exit temperature distribution in the combustor. Preliminary results have shown good ability to control pattern factor this way. 

UV-Vis process analysers can be used in a noncontact mode as the source radiation can be passed though a window in a process pipe, for example, and the emitted radiation detected on the other side of the pipe. This means that the sample can be subjected to a measurement without its flow being impeded or its composition changed in any way. Optical fibres are used to transmit the radiation to and from the sample, which can be in a distant location, a hazardous area or in a harsh environment such as a high temperature reaction vessel. The most common forms of optical fibre probes used for UV-Vis measurements are of the transmission and ATR types (Figure 9.12). The petroleum and chemical industries use UV-Vis spectroscopy for monitoring many of their processes ... 

The investigator who wants to make an EDL is thus faced with a very large amount of information dispersed in the literature and finds it very difficult to reproduce these procedures to develop EDL with the properties desired. An experimental vacuum system for EDL (Hg, Hgl2, Cd, T, KI, P, Se, S) manufacture has recently been designed by Cirkva and coworkers (Fig. 19.4) [58]. The technique is very simple and enables the preparation of EDL in a conventional chemistry laboratory. Examples of EDL are shown in Fig. 19.5. EDL performance is tested to prepare the lamps for spectral measurements [58]. A typical experimental system for such testing comprises a round-bottomed flask, placed in a MW oven, containing n-heptane and equipped with fiber-optic temperature measurement, a spectral probe, and a Dimroth condenser (Fig. 19.6). 

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