Reconstructed linear absorption

The reconstructed linear absorption values for a cross section of the jet (12.7mm above the exit plane) for the case of twelve angles is shown in Figure 3. Qualitatively the reconstructed field shows the expected jet jrofile. Using an absorption coefficient of 10 atm cm extrapolated from the results of McMahon et.al. (5), the center line concentration of methane is found to be 9.6%. Since the measurements were taken close to the jet exit the potential core of the flow is observed to survive to the measurement point. Thus the methane concentration would be expected to be the 10% initially introduced. Therefore good agreement is observed with respect to concentration measurement. The position of the jet center line was obtained from the location of the peak values of the linear absorption coefficients. This approach yielded a position of 19 1.3 mm which compares quite well with the known position of 19 mm. This is further confirmation of the accuracy of the reconstruction algorithm. 

The mathematical reconstruction of a property field, F(x,y), from its projection in the 0 direction is the basis of "Computerized Tomography" (1,2). An identical technique can be used to reconstruct a field of linear absorption coefficient functions in a combusting flow field from multiangular path integrated absorption measurements. The linear absorption coefficient is the familiar N.Q. product, where is the concentration of species i and Q. is the absorption cross section of species i at the frequency v. The Bouguer-Lambert-Beer law states that... 

The linear absorption coefficient functions can thus be reconstructed using only projection data. 

After creating the concentration profiles (Figure 6), an absorption profile was generated fi-om the pure component spectra using eq 9, and the spectral data matrix was reconstructed as a linear combination of the component spectra. The best fit was obtained using the simplest mechanism, A - B C, and was taken as the plausible mechanism. Using this mechanism and the extinction profiles, absorption spectra at different time points were calculated (Figure 7). TTie SVD derived kinetic parameters were compared with those obtained (7) from the... 

Two-Photon Confocal Microscopy. Confocal microscopy provides the possibilities of optical sectioning of a sample by the use of a spatial filter to improve axial resolution of the optical microscope (20). These optical sections can be used to reconstruct the 3D structure of a polymeric specimen. Confocal microscopy using fluorescence is usually performed by a single-photon excitation (linear absorption) of a fluorophore which may be chemically an integral part of the system (polymer) being investigated or just... 

It can be seen that the maximum values ratio of the measured values is basically coincide with the theoretically analyzed one. Only for parallel linearly polarization hologram, in the orthogonal linearly polarization reconstruction condition C 0 / / R), the diffraction efficiency is lower than parallel linearly polarization reconstruction condition (C//0//R). Itis because that, in calculation the affection of C is not considered, which can be proved to be very small when the Ic=Io/ 100=Ir/ 100 comparing to the affection of non-linear absorption of the film, whose detail calculation progress will not be given here, where it also can be deduced that the reading beam affection is larger in C O // R condition than in C//0//R condition. 

These results were further confirmed using the LPSIRS technique developed by Kunimatsu. In this technique, the change of reflectance is recorded at various fixed wavenumbers, while the electrode potential is varied linearly. It is then possible to reconstruct the absorbance spectrum at a particular potential by taking the difference between the reflectance at this potential and that at a reference potential where no adsorbed species exists. This gives normal absorption spectra, displaying the same type of bands as in EMIRS measurements. 

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