Optical Fiber Measurements

Optical fiber measurement of local solids concentrations of FCC catalyst fluidized in a 9-cm-i.d. column gave the results shown typically in Fig. 26. Analysis of these data showed that the radial voidage profile could be described solely by the cross-section-average voidage e, calculated as shown in Sec. 5.1, and the reduced radial coordinate r/R ... 

Fig. 6. Instrumentation for optical-fiber measurement and alternate-layer arrangement of fibers (after Qin and Liu, 1982).

Fig. 8 Excitation geometry for direct illumination of surface bound molecules. Image on the left shows the modified fiber optic cormector with a fluid port and adjacent optical fiber. Measured nearfield intensity distribution of the distal end confirms propagations of leaky modes...

FIGURE 4-26 Comparison of particle velocities determined by LDV and cross-correlation of optic fiber measurement (Yang et al., 1992)... 

Lischer, D.J., and Louge, Optical Fiber Measurements of Particle... 

Culshaw, B. Habel, W.R. Fibre sensing Specifying components and systems. Symp. on Optical Fiber Measurements SOFM 2004, Session X Fiber Bragg gratings and fiber sensors. Boulder, Colorado, USA, September 28-30 (2004)... 

Through optical fiber measurement, we now know that the bimodal probability distribution exists over the entire range of sofids volume fraction. For a high-velocity CFB, one peak of the bimodal distribution corresponds to the dense cluster phase and the other to the dilute broth phase (Li and Kwauk, 1994). For a low-velocity, bubbling fluidized bed, this bimodal... 

Lischer DJ, Louge M. Optical fiber measurements of particle concentration in dense suspensions calibration and simulation. Applied Optics 31 5106-5113, 1992. 

Marcuse, D. (1981) Principles of Optical Fiber Measurements, Academic Press, New York, pp. 226-232. 

Marcuse D., In Principles of optical fiber measurements. Academic Press, NY, 1981, pp. 141 - 156. 

Ren B, Li W H, Mao B W, Gao J S and Tian Z Q 1996 Optical fiber Raman spectroscopy combined with scattering tunneling microscopy for simultaneous measurements ICORS 96 XVth Int. Conf on Raman Spectroscopy ed S A Asher and P B Stein (New York Wley) pp 1220-1... 

Nonintrusive Instrumentation. Essential to quantitatively enlarging fundamental descriptions of flow patterns and flow regimes are localized nonintmsive measurements. Early investigators used time-averaged pressure traverses for holdups, and pilot tubes for velocity measurements. In the 1990s investigators use laser-Doppler and hot film anemometers, conductivity probes, and optical fibers to capture time-averaged turbulent fluctuations (39). 

Durand, M. (1984), Use of Optical Fibers for Velocity Measurement by Laser Doppler Interferometry with a Fabry-Perot Interferometer. In High Speed Photography and Photonics, Proc. SPIE, 491 (edited by M. Andre and M. Hugenschmidt), pp. 650-656. 

Several practical issues of the scatterometer must be considered in the case of characterizing nominally smooth surfaces. The incident laser beam may be collimated, but more commonly it is brought to a focus at a distance defined by the arc in which the detector rotates. In addition, a deflection mirror or an optical fiber might be used to direct light to the detector element. These features permit measurements close to the specular and transmitted beams, and this is critical to folly characterize the scattered light. This is especially significant since the scattered light intensity... 

The quantitative assessment of the overall orientation of PET fibers is generally made on the basis of fiber optical anisotropy measurements, i.e., measurements of the optical birefringence of the fiber. The determination of the value of optical birefringence makes it possible to determine the value of Hermans function of orientation based on the equation ... 

Shang, H.-T., 1981, Chromatic dispersion measurement by white light interferometry on meter-length single-mode optical fiber, J. Opt. Soc. Am., 71, 1587... 

The experimental set-up for the FCS measurement is illustrated schematically in Figure 8.6. A CW Ar laser (LGK7872M, LASOS lasertechnik GmbH) at 488 nm was coupled to a single mode optical fiber to isolate the laser device from an experimental table on which the confocal microscope system was constructed. This excitation laser light transmitted through the optical fiber was collimated with a pair of lenses, and then was guided into a microscope objective (lOOX, NA 1.35, Olympus). 

Measurement by means of a wall optical sensor The thickness of a film and the slope of its free surface can also be measured by means of a wall optical sensor, as proposed by Ohba et al. (1984). This sensor consists of a cluster of seven optical fibers mounted flush with the wall (Fig. 3.33). A laser beam passed through the central fiber is reflected by the free surface onto the other fiber tips, which collect the light and transmit it to two photodiodes. The light intensities received by these two detectors enable the film thickness and the inclination angle to be determined. 

Qin, S., and Liu, G., Application of Optical Fibers to Measurement and Display of Fluidized Systems, Proc. China-Jpn. Fluidization Symp., p. 258-266, Hangzhou, China (1982)... 

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