Photon migration

15 Turbo-Power Model TPO-400 in-line grain size analyzer 

Nisshin developed this instrument for the cement industry. At preset times it automatically samples a few kilograms of material and feeds it into a turbo classifier. The fines are fed into a micron line that determines the Blaine number for the powder. 

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Another promising alternative to the rather restrictive MBLL model is the layer model using diffusion equation. Diffuse optical imaging provides a better model for photon migration where approximation of path length is possible. This would provide a much improved focal change information and potentially eliminate crosstalk noise. 

R. F. Bonner, R. Nossal, S. Havlin, and G. H. Weiss. Model for photon migration in turbid biological media. Journal of the Optical Society of America A, 4(3) 423-432, 1987. 

G. Gratton and P. M. Corbaliis. Removing the heart from the brain Compensation for the pulsatile artifact in the photon migration signal. Psychophysiology, 32 292-299, 1995. 

Other near-IR applications which use similar pulse and phase instrumentation as used in lifetime measurements include optical time-domain reflectometry(25) and photon migration in tissue. 26 ... 

Cusack, J. Photonics at Rome Laboratory, Microwave /., 72 (February 1992). Fujimoto, J.G. and M.S. Patterson Advances in Optical Imaging and Photon Migration, Optical Society of America, Washington, DC, 1998. 

The foundation for the development of these techniques is built on investigations into photon migration processes [2, 9]. Subsequent, detailed examination by Everall et al. [10, 11] demonstrated that the inelastically scattered (Raman) component decays substantially more slowly than its elastically scattered counterpart (i.e. the laser light) due to the regeneration of the Raman signal from the laser component. Discrimination between diffusely scattered photons and the ballistic and snake components is achieved by gating the detector in the temporal or spatial domain. 

Frequency domain photon migration (FDPM) has been investigated as an optical technique with potential application to particle size analysis,67 albeit in a laboratory environment. The approach could be readily implemented in situ, with appropriate... 

Sun, Z. Torrance, S. McNeil-Watson, F.K. etal., Application of frequency domain photon migration to particle size analysis and monitoring of pharmaceutical powders Anal. Chem. 2003, 75, 1720-1725. 

Pan, T. 8t Sevick-Muraca, E.M., Volume of pharmaceutical powders probed by frequency-domain photon migration measurements of multiply scattered light Anal. Chem. 2002, 74, 4228M234. 

Sun, Z. Huang, Y. Sevick-Muraca, E.M., Precise analysis of frequency domain photon migration measurement for characterization of concentrated colloidal suspensions Rev. Sci. Instrum. 2002, 73, 383-393. 

Tromberg BJ, Shah N, Lanning R, Crussi A, Espinoza J, Pham T, Svacsand L, Butler J. Non-invasive in vivo characterization of breast tumors using photon migration spectroscopy. Neoplasia 2000, 2, 26 10. 

Yamada Y. Fundamental studies of photon migration in biological tissues and their... 

Sample variability is a critical issue in prospective application. For optical technologies, variations in tissue optical properties such as absorption and scattering coefficients can create distortions in measured spectra. This section provides a brief overview of techniques to correct turbidity-induced spectral and intensity distortions in fluorescence and Raman spectroscopy, respectively. In particular, photon migration... 

In fluorescence spectroscopy, however, diffuse reflectance correction of spectral distortions in biological media has been studied extensively. Analytical models based on photon migration theory,44 diffusion theory46,60,61 as well as empirical models,62 have been reported to obtain intrinsic fluorescence. In the following, we will review a particular correction method based on photon migration theory for fluorescence spectroscopy and introduce its Raman counterpart. 

Das, B.B., Liu, R, and Alfano, R.R. (1997) Time-resolved fluorescence and photon migration studies in biomedical and model random media. Reports on Progress in Physics, 60, 227-292. 

A method for on-line monitoring of particle size distribution and volume fraction in real time using frequency domain photon migration measurements (FDPM) has been described. In FDPM the time dependence of the propagation of multiply scattered light provides measurement of particle size distribution and volume fraction. The technique has been applied to a polystyrene latex and a titanium dioxide sluny at volume concentrations in the range 0.3 to 1% [341]. 

The technique is fast and the equipment relatively inexpensive. Moreover, since photon migration measures the time it takes for light to travel through the sample rather than the intensity of the detected signal, it is self-calibrating. 

The fetus was considered in a paper by Vishnoi et al. [147]. In this paper, they describe the measurement of photon migration through the fetal head in utero using a continuous-wave NIR system. The same topic was addressed by Ramanu-jam et al. [148], using antepartum, transabdominal NIR spectroscopy. A similar paper by Calvano et al. [149] discusses am-nioscopic endofetal illumination with infrared (NIR) guided fiber. 

Milne et al. [154] have developed stereotactically guided laser thermotherapy for breast cancer in situ measurements. They determine the temperature field within the breast to highlight potential tumors. A review paper by Tromberg et al. [155] discusses the noninvasive in vivo characterization of breast cancer tumors using photon migration spectroscopy. They compare the use of this technique with straightforward NIR spectroscopy. 

C. H. Barlow et al., Tissue Temperature by Near-Infrared Spectroscopy, in Optical Tomography, Photon Migration, and Spectroscopy of Tissue and Model Media (B. Chance and R. R. Alfano, eds.), SPIE, 2389, 818 (1995). 

G. Vishnoi, A. H. Hielscher, N. Ramanujam, and B. Chance, Photon Migration Through Fetal Head in Utero Using Continuous Wave, Near-Infrared Spectroscopy Development and Evaluation of Experimental and Numerical Models, J. Bio-med. Optics, 5(2), 163-172 (2000). 

N. Ramanujam, H. Long, M. Rode, I. Forouzan, M. Morgan, and B. Chance, Antepartum, Transabdominal Near-Infrared Spectroscopy Feasibility of Measuring Photon Migration Through the Fetal Head in utero, J. Maternal-Fetal Med., 8(6), 275-288 (1999). 

B. J. Tromberg, N. Shah, R. Lanning, A. Cerassi, J. Espinoza, T. Pham, L. Svaasand, and J. Butler, Non-Invasive in vivo Characterization of Breast Tumors Using Photon Migration Spectroscopy, Neoplasia, 2(1-2), 26-40 (2000). 

Several deep, noninvasive approaches have been developed following earlier extensive investigahons into the photon migration process [3,10-12]. The methods can be divided into two basic classes, namely temporal and spatial. 

Phase shift fluorimetry, the other important method for measuring fluorescent lifetimes, also continues to be developed and improved. The effects of Inaccurate reference lifetimes on the interpretation of frequency domain fluorescence data can be removed or minimized by a least squares analysis method.The direct collection of multi-frequency data for obtaining fluorescence lifetimes can be achieved by the use of digital parallel acquisition in frequency domain fluorimetry. Frequency domain lifetime measurement has been used for on-line fluorescence lifetime detection of eluents in chromatography. An unusual use of frequency domain measurement which has been reported is for the examination of photon migration in living tissue. Photons in the... 

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