Temperature Dependence of the Refractive Index

In 10 there a great variety of materials is used, and their optical constants may be affected e.g. by film deposition technologies. What is thus required is the access to data for material dispersion with relation to technological parameter as well, either as Sellmeier or related formula, or as tabulated values. Additionally, refractive indices respond to temperature, which may be intended for device operation in case of a TO-switch, or unintended in field use. The temperature dependence of the refractive index can be attributed to the individual material, simply, but the influence of heater electrodes needs special consideration. If an 10 design-tool comes with inherent TO or EO capabilities, those effects are taken into account in the optical design directly. 

The temperature dependence of the refractive index has been evaluated with the empirical Eykman equation ... 

Fig. 2. Temperature dependence of the refractive index of cured SIEL MPh compounds for different contents of methylphenylsiloxy units.

From these data determine the second virial coefficient and the theta temperature of poly(a-methyl styrene) in cyclohexane, knowing that K = K hl AhlAcf, where K = 18.17 mol cm , the refractive index increment (d /dc) is 0.199 ml gr, and the temperature dependence of the refractive index is expressed by = -0.0005327 x T (°C) + 1.446. Static light-scattering measurements were carried out by Zimm (1948b) on polystyrene in butanone at 340 K at two concentrations. 

Recently it has been observed that the thermal grating response of a nematic is unusually large. The property exploited is the temperature dependence of the refractive index. This effect has considerable history, where prior experiments used a solvent containing a dye, e.g., rhodamine 6G in ethanol. The optical energy is absorbed by the dye and then transferred to the solvent, resulting in a thermal grating and consequent index grating. The time constant of this process in ordinary liquids is of nanosecond order. 

FIG. 2. Shift of temperature dependence of the refractive index of an NLC with changing temperature of the phase transition temperature. The induced refractive index at a given temperature is determined by the shape of the n(r) curve and the value of the shift of, while the sign of t is determined by the sign of the change of. ... 

The same experimental set-up, as described above, was used, except the samples were now placed in a temperature-controlled chamber. As seen in figure 13, the temperature of a PLZT (9.5/65/35) was varied from 20°C down to -30°C, up to 60°C and down again to 20°C. Only a slight hysteresis was found for these results. The temperature dependence of the refractive index change An of PLZT (9.5/65/35), without any applied field, was found to be linear in the above range, with a positive slope of An / AT in equation (8), which corresponds to the approximately 11% to the calculated slope. 

Fig, 19.24, Temperature dependence of the refractive index of EuO, EuS and EuSe prismatic single crystals. In the dash-dotted part of the curves appreciable light scattering due to magnetic domains occurred (after Wachter, 1968b). 

Temperature Dependence of the Refractive Index. The refractive index is also dependent on temperature. This temperature dependence is represented by Awrei/ AT for an air pressure of 1013.3 hPa and Awabs/AT in vacuum. The following equation is derived from the Sellmeier formula and is valid with the given coefficients in the temperature range —40 °C[Pg.548]

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