Mismatch in refractive indices

Figure 5. Possible origins of light scattering in the composite film (1) a spatial distortion of nematic directors, (2) a discontinuous change of nematic directors among different LC domains and (3) the mismatch in refractive indices of the components. Also, the turbid and transparent changes are shown under the conditions of off- or on-a.c. electric fields, and mesomorphic- or isotropic- phases.

Although the liquid-liquid two-fluid flow has the same phase in the viewpoint of state of matter, some problems might be encountered when utilizing PIV to measure the velocity field(s) in one or both of fluid flows, such as mismatching of refractive indices of the two fluids, physical properties that influence the mixing of seeding particles, resolving the two fluids from each other, etc. 

PDLCs comprise LC droplets dispersed in a polymer matrix. Random director orientation leads to the scattering of light due to refractive index mismatch between LC and polymer. A field applied across the film orients the LC so that the refractive indices match and the scattering is reduced, rendering the film transparent. 

Hence, extrapolating to 100 C, the refractive index would be about 1.375 which is a sizable change in refractive Index units. Although the refractive indicies may be matched at room temperature, at elevated temperature there develops a mismatch and consequently there is an increase in haze. The new silica filler compositions show some temperature dependent haze, however not to as great an extent as compositions which depend upon matched refractive indices to achieve optical clarity. Table IX shows these differences in temperature dependent haze. For applications which require optical transparency over a range of temperatures, the new silica filled compositions offer a distinct advantage. 

This approach to assessing STH from two overlayed three-electrode measurements often overestimates the true two-electrode performance, mainly because integration of multiple material components is rarely a perfect process. Factors include lost illumination (e.g. catalyst shadowing, mismatched refractive indices resulting in increased reflection, absorption mismatched band gaps), ohmic resistance (iR) losses, and non-ideal interfacial engineering of the various... 

In examining unstained and otherwise transparent biological objects, where contrast in the image must be achieved by phenomena other than the differential absorption of light, contrast will be increased according to the degree of mismatch between the refractive indices of specimen components and mountant, as discussed below for nonbiological objects. 

One very important advantage of FLCPs over amorphous poled polymers is the possibility of phase matching, which is a precondition for efficient SHG. The mismatch of the refractive indices of the fundamental wave and the second harmonic due to the dispersion may be overcome using the birefringence of the FLC material in the geometry shown in Fig. 37 [15]. Due to the C2 symmetry of the unwound smectic C phase (achieved by surface stabilization or by application of a DC electric field along the y direction), the tensor has only four independent elements, which may be denoted in the contracted d tensor notation as... 

Fig. 5.14. A polymer dispersed liquid-crystal (PDLC) device consisting of a microdispersion of a low molecular weight nematic fluid (MLC) in a conventional transparent polymer host matrix sandwiched between thin coats of transparent, conducting tin oxide. On the left is shown the off state with a refractive-index mismatch between the dispersion and the host that scatters incident light. On the right is shown how an external electric held aligns the director of the nematic matching the refractive indices of the dispersion and the host, yielding an optically transparent medium.

The parameters and are close to 1 if the refractive indices of successive media are not very different and A2 1. In this case, Eq. (13) can be represented graphically in complex plane as shown in Fig. 9, where the angle represents the phase mismatch between fundamental and harmonic waves... 

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