Optical measurement techniques

J. A. Valdmanis, Electro-Optic Measurement Techniques for Picosecond Materials, Devices, and Integrated Circuits... 

The problem with the Clark electrode is that some of these requirements have solutions that are opposing. For instance, flow dependence may be reduced by employing a thicker membrane but this would occur at the cost of increased response time. As a result, most commercially available systems are design compromises that sacrifice a part of some desirable feature. It should he noted that an optical measurement technique where oxygen and/or electrolyte is not consumed will be free of the drawbacks mentioned above. 

In combination with optical measurement techniques, the large size of the MIP particles can give rise to light scattering problems. The use of imprinted membranes may avoid this limitation. 

The bubble size distribution was also measured at a cell potential of 3.3V and is given in figure 3. To that purpose backlighting or shadowgraphy, being an in situ and non-intrusive optical measurement technique, was used. 

Fig. 3-7. Vertical distribution of nitrogen oxides and nitric acid in the stratosphere. Left Nitric oxide in the sunlit atmosphere the fields enclose data obtained with the chemiluminescence technique (Horvath and Mason, 1978 Roy et at, 1980 Ridley and Schiff, 1981 Ridley and Hastie, 1981) horizontal lines represent measurements by infrared optical techniques (Drummond and Jarnot, 1978 Roscoe etal., 1981 Loewenstein etal., 1978a,b). Center Nitrogen dioxide as observed by optical measurement techniques, day (d) and night (n) points indicate data from Murcray et al. (1974), Goldman et al. (1978), Blatherwick et at (1980) horizontal bars are from Drummond and Jarnot (1978) and Roscoe et al. (1981). The N205 profile was obtained by Toon et al. (1986) at sunrise. Right Nitric acid observed by in situ filter sampling (open points) (Lazrus and Gandrud, 1974) and by infrared spectroscopy and mass spectroscopy (solid points) (Fontanella et at, 1975 Harries et al., 1976 Evans et al., 1978 Arnold et al., 1980 Murcray et al. as quoted by Hudson, 1982 Fischer et at, 1985). The envelope gives the error range.

Mayinger, F., (ed.) Optical Measurements Techniques and Applications. Springer-Verlag. (1994). 

A variety of optical techniques have been used to measure gas temperatures in combustion applications, particularly in flames. There are potentially some important advantages of optical techniques compared to contact techniques such as suction pyrometers (see Figure 5.7). Optical measurement techniques do not disturb the flow, where thermocouples may have a significant impact on the fluid dynamics. Optical techniques can potentially measure higher temperatures as there are not the materials issues compared to thermocouples. For some optical techniques, temperature profiles can be measured at one point in time without the need to make multiple individual measurements over some length of time. Optical techniques often have a much faster response time compared to contact methods. This is particularly important in turbulent and transient flows. 

J. M. Link, C. Zeilstra, N. G. Deen and J. A. M. Kuipers, Validation of a discrete particle model in a 2D spout-fluid bed using non-intrusive optical measuring techniques, Can. J. Chem. Eng., 2004, 82, 30. 

Far-field optical measuring technique is in its burgeoning stage and could provide new opportunity for nanofluidics in lab-on-a-chip research. 

Cuypers W, Van Gestel N, Voet A, Kruth J-P, Mingneau J, Bleys P (2009) Optical measurement techniques for mobile and large-scale dimensional metrology. Opt Lasers Eng 47 (3) 292-300... 

Bureau of Standards 67G, no. 3 (1963) 217-226. Regarded as a pioneering piece of work in developing optical measurement techniques for temperature based on the emittance of various materials and media. 

Ziari, M., Kalluri, S., Gamer, S., Steier, W. H., Liang, Z., Dalton, L. R., and Shi, Y, Novel electro-optic measurement technique for coplanar electrode poled polymers, Proc. SPIE, 2527, 218-227 (1995). 

Hebner, R.E., 1986, Electro-optical measurement techniques, d "Fast... 

Fluorescence measurements and detection can either be made under steady-state or time-resolved conditions. Some of the commonly used measurement techniques focus on changes in optical properties such as fluorescence intensity quenching, phase fluorometry (lifetime), polarization, surface plasmon resonance (SPR), and evanescent waves. Here, we will present detector systems based for (a) fluorescence intensity quenching and (b) phase fluorometry in detail. A few example references of integrated optical sensor systems based on the various optical measurement techniques are given in Table 1 and the reader is encourage to review those papers if more details are desired. 

Optical measurement techniques, Particle Image Velocimetry and Particle Tracking Velocimetry, to measure the flow pattern in a model silo made of perspex were used successfully. Thereby, the velocities at the vertical silo walls were measured. Using these techniques, local velocities were measured in fimnel-flow silos as well as in mass-flow silos. For fimnel-flow, the separation hne between moving and stationary bulk solid were determined. It was found that the velocity profiles in silos are not symmetrical and change with time. 

Spray properties are mostly determined with optical measurement techniques. For the analysis of the droplet diameter Shadowgraphic methods, laser diffraction or Phase Doppler Anemometry (PDA) have been used elsewhere [1, 2, 11, 18]. Droplet velocities can be measured with Shadowgraphy, Particle Image Velocimetry (PIV), or PDA [1, 6, 19]. The determination of the spray temperature is possible with Global Rainbow Thermometry (GRT), Planar Laser Induced Fluorescence (PLIF), and Differential Infrared Thermography (DIT) [20-22]. 

Heffels, C. M. G., Polke, R., Radle, M., Sachweh, B., Schafer, M., Scholz, N., Control of Particulate Processes by Optical Measurement Techniques, Part. Part. Syst Charact, 1998, 15,211-218. 

---