Loss mechanisms refraction

Core and cladding materials are selected not only on the basis of their refractive index, but also for their processability, attenuation loss, mechanical properties, and dispersion properties. However, density, p, and refractive index, n, are critical and have been correlated for over 200 optical glasses, for which the following formula... 

After subjecting the two materials to ultrasonic irradiation, the formation of anthracene was confirmed by photoluminescence spectroscopy. The photoluminescence intensity increases with increasing sonication time (Fig. 30b), which confirms the arm-loss mechanism. Quantifying anthracene (using the photoluminescence intensity at 411 nm) yields two similar reaction constants (3.20 0.14) X 10 and (3.26 0.09) x 10 min for the star and linear polymers, respectively. Boydston also calculated the reaction constant based on refractive index signals (change of M. Again, he obtained two similar reaction constants (3.13 0.11) x 10 and (3.27 0.38) x 10 min for star and linear polymers, respectively. His result reveals the equivalence between star-shaped polymers and linear polymers in terms of chain scission rate if of star-... 

With a test sample on the optically flat top surface of the bar, the pulse echo train is reduced in amplitude. This attenuation is owing to the refraction of part of the ultrasonic wave into the test sample at the frequency used. The ratio of successive peak amplitudes may be measured on the oscilloscope and expressed in decibels loss per echo. From this, the loss per echo with no sample on the bar can be substracted to give a value Adb which is related to the mechanical shear impedance of the sample. Rapid changes can be conveniently monitored by a recorder which follows the peak signal of a selected echo. 

For the selection of optical windows, besides such parameters as useful spectral range, mechanical resistance and solubility, the refractive index also has to be taken into account The refractive index of the windows should match that of the liquid sample in order to minimize reflection losses, stray light and distortions of band shapes (Christiansen effect). NaCl and KBr are very suitable for organic analytes. Inorganic analytes may have much higher refractive indices. The higher the refractive index, the higher the reflection losses for the incident IR radiation. 

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