Real refractive index

C REFMED = (REAL) REFRACTIVE INDEX OF SURROUNDING MEDIUM... 

The results of this model calculation can be used to extract unknown film properties, such as the film refractive index and thickness. Normally, however, an ellipsometer will yield only two independent observables (the two ellipsometric angles defined in equation (3.6), for example). For that reason, only two film properties can be extracted from a single measurement. If the film is nonabsorbing with a real refractive index, an ellipsometric measurement can provide the real part of the refractive index, n, and the thickness. For... 

For water droplets (m = 1.33), a plot of Qext versus a is shown in Fig. 16.3. Oscillations in the value of Qext are due to internally reflected light being in or out of phase during scattering. Also shown is a plot for a material having the same real refractive index as water but a small and intermediate absorption component (m = 1.33 - O.Oli and m = 1.33 - O.lz). The effect of absorption on oscillations in Qext as the absorption component increases can be clearly seen. 

The considerations before refer to the non-absorbing case when and n are real quantities. In order to characterize the optical properties completely absorption must be included. This can be achieved by taking the optica] and dielectric functions to be complex quantities comprising two real figures each. The (real) refractive index n is complemented by the real absorption index k to constitute the complex refractive index... 

For the weak oscillator the shapes of all graphs related to h and e are symmetrical with respect to the resonance frequency, pairwise similar, and no distinctive wavenumber shift is found. The reflectance spectrum resembles closely the dispersion anomaly of the (real) refractive index. The spectral variations of the components of the dielectric function are... 

For the strong oscillator the n and k spectra are asymmetric. The shift of the k maximum away from the resonance frequency is particularly obvious. In such a case a reliable representation of the vibrational structure cannot be derived from transmittance spectra and thus, from the absorption index k alone. Another peculiarity of the strong oscillator is the spectral range where the (real) refractive index is below unity. This renders... 

V indicates the principal value) are applied to a function F = F + F" (Bode, 1950 Smith, 1985 Hopfe et al., 1981). Such so-called dispersion relations exist between the (real) refractive index and the absorption index. Dedicated software programs are available, also specially for (infrared) spectroscopic purposes (Hopfe, 1989), a generalization for oblique incidence on layered systems was given by Grosse and Offermann (1991). 

The above relationships (Figure 1.10) show that the optical pigment properties depend on the particle size D and the complex refractive index n = n (1 - i/c), which incorporates the real refractive index n and the absorption index k. As a result, the reflectance spectrum, and hence the color properties, of a pigment can be calculated if its complex refractive index, concentration, and particle size distribution are known [1.40]. Unfortunately, reliable values for the necessary optical constants (refractive index n and absorption index k) are often lacking. These two parameters generally... 

At mtermediate electrolyte concentrations ( 10 mol dm" ) and at low volume fractions of the dispersed phase, the charged particles occupy random positions in the system and undergo continuous Brownian motion with transient repulsive contacts when the particles approach each other. The range of the electrostatic repulsive forces is represented by the dashed circle in Fig. 1. which implies that when a similar circle on another particle overlaps with it on a collision trajectory, a transient electrostatic repulsion occurs and the particles move out of range. With most latices the particles. have a real refractive index and their visual appearance is milky white. 

Ferrare R. A., Meffi S. H., Whiteman D. N., Evans K. D., Poellot M., and Kaufman Y. J. (1998b) Raman hdar measurements of aerosol extinction and backscattering 2. Derivation of aerosol real refractive index, single-scattering albedo, and humidification factor using Raman hdar and aircraft size distribution measurements. J. Geophys. Res. 103, 19673-19689. 

In Eig. 1 the beam trajectories are sketched for a wave incident on a plane interface between two media having a real refractive index rij and H2, respectively. The incoming beam with amplitude El is reflected by the interface, giving a reflected beam with amplitude E2 and a transmitted beam with amplitude E3. 

Figure 2 The scattering problem illustrated for a spheroidal particle with orientation e and effective refractive index = n — i k. The surrounding medium is nonabsorbing, with the real refractive index ne, The speed of light within the medium is c = Co/r e, where Cq is the speed of light in vacuum. The incident plane wave has frequency v (ie, wavelength X = dv) and a wave vector collinear to o. A propagation direction of the radiation scattered by the particle is denoted as a. 0 is the angle between a and co. ...

As a result, the angles cpt become complex. It is not expedient to undertake doubtful attempts to interpret the complex angles of incidence and refraction they should simply be considered as mathematical representations. The real angle of refraction of the beam in an absorbing medium is calculated on the basis of the Huygens-type construction via the effective (real) refractive index of the medium, which is not equal to either , or n, [9, 52]. 

From Equations (8.23), (8.28), and (8.29), the required film thicknesses depend on the incident angle Oq, the film s refractive indices a+,e> a+,o. a-,e. and na-o, and the polarizer s average real refractive index tip. Therefore, once we know the refractive indices of both the films and the polarizer, as well as the intended viewing angle for LCD optimization, we can determine the required film thickness from Equations (8.23), (8.28), and (8.29). By using the parameters listed in Table 8.2 and choosing 0o = 70°, the required film thicknesses as... 

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