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Extraordinary beam

Polarized light is obtained when a beam of natural (unpolarized) light passes through some types of anisotropic matter. In optical instruments this is usually a birefringent crystal which splits the incident unpolarized beam into two beams of perpendicular linear polarization, known as the ordinary and extraordinary beams. Anisotropy can also be created by the effect of an electric field, this being known as the Kerr effect. [Pg.24]

A light beam falling normally on the entrance face of the polarizer is split into ordinary and extraordinary beams that propagate together until they reach the oblique face where the ordinary beam experiences total reflection. The extraordinary beam polarized perpendicularly to the optical axis of the crystal enters the second triangle prism and emerges from it with unchanged polarization. The symmetric construction of the polarizers ensures that both sides can be used as a beam entrance. [Pg.92]

Figure 4.6-5 Infrared linear dichroism of a nematic sample (EBBA/MBBA equimolar mixture of N-(p-ethoxybenzylidene)-//- -butylaniline and its methoxy analogue 2 of Table 4.6-1 Riedel-de Haen) expressed as the difference of the absorption indices k and ke (imaginary part of the complex refractive index) for the ordinary and the extraordinary beam, resp. the temperature increases and thus, the degree of order decreases from spectrum a to spectrum d, the latter was taken close to the clearing point F, where the order and consequently the anisotropy vanishes (Reins et al., 1993). Figure 4.6-5 Infrared linear dichroism of a nematic sample (EBBA/MBBA equimolar mixture of N-(p-ethoxybenzylidene)-//- -butylaniline and its methoxy analogue 2 of Table 4.6-1 Riedel-de Haen) expressed as the difference of the absorption indices k and ke (imaginary part of the complex refractive index) for the ordinary and the extraordinary beam, resp. the temperature increases and thus, the degree of order decreases from spectrum a to spectrum d, the latter was taken close to the clearing point F, where the order and consequently the anisotropy vanishes (Reins et al., 1993).
Little is known about infrared refractive indices of organic compounds, and only very few such studies related to liquid crystals are reported. To some extend this is due to the fact that special techniques and even dedicated equipment are required. On the other hand birefringence can be derived from the polarization pattern produced by the phase difference between the ordinary and the extraordinary beam. This experiment had been outlined by Born and Wolf (1980) and was applied to liquid crystals by Wu et al. (1984). The procedure is primarily suitable in transparent regions, for a more comprehensive optical characterization it should be extended to complete ellipsometry (Reins et al., 1993). Results obtained by infrared-spectroscopic ellipsometry are shown in Figs. 4.6-5 and 4.6-6. [Pg.332]

Figure 4 An acousto-optic tunable filter [a, tellurium dioxide (Te02) crystal b, incident or input beam c, acoustic transducer d, rf input e, monochromatic light (ordinary beam) f, nonscattered light beam g, monochromatic light (extraordinary beam) h, acoustic wave absorber]. Figure 4 An acousto-optic tunable filter [a, tellurium dioxide (Te02) crystal b, incident or input beam c, acoustic transducer d, rf input e, monochromatic light (ordinary beam) f, nonscattered light beam g, monochromatic light (extraordinary beam) h, acoustic wave absorber].
Figure 2. Schematic of the vacuum UV CD apparatus (A) 200-W deuterium lamp (B) CaFi collimating lens (C) McPherson 218 monochromator vacuum chamber (D, E) focusing mirrors (F) plane grating (G) MgFe rochon polarizer (H) modulator (I) CaF, lens (J) sample chamber at atmospheric pressure (K) mask for extraordinary beam, (L) photomultiplier (6). Figure 2. Schematic of the vacuum UV CD apparatus (A) 200-W deuterium lamp (B) CaFi collimating lens (C) McPherson 218 monochromator vacuum chamber (D, E) focusing mirrors (F) plane grating (G) MgFe rochon polarizer (H) modulator (I) CaF, lens (J) sample chamber at atmospheric pressure (K) mask for extraordinary beam, (L) photomultiplier (6).
A more common way of building an intensity modulator uses two LiNbOj crystals in tandem. The crystals are arranged in a set-up similar to that in an amplitude modulator and are positioned so that the external field is applied parallel to the optical axis and the light beam travels perpendicular to it. However, the crystals are positioned so that the x- and y-axes are arranged at an angle of 45° to each other. The entry beam is accurately polarised vertically so that its electric vector bisects the x-andy-directions (Figure 9.12). This will split into an ordinary and extraordinary ray, each with polarisation normal to the other as it enters the first crystal. The second crystal is oriented so that the ordinary and extraordinary rays in the first crystal, defined by their relative polarisation, swap and become the extraordinary and ordinary rays in the second crystal. In this way, the ordinary and extraordinary beams travel identical optical paths. On emerging, the ordinary and extraordinary waves will have a phase difference due to the imposed values of the external electric field and will be linearly polarised perpendicular to one another. [Pg.298]

In the shortened notation (ooe, eoe,. .. ). the frequencies satisfy the condition wavelength radiation, and the last symbol refers to the shortest-wavelength radiation. Here the ordinary beam, or o-beam is the beam with its polarization normal to the principal plane of the crystal, i. e. the plane containing the wave vector k and the crystallophysical axis Z (or the optical axis, for uniaxial crystals). The extraordinary beam, or e-beam is the beam with its polarization in the principal plane. The third-order term is responsible for the optical Ken-effect. [Pg.826]

For uniaxial crystals, the difference between the refractive indices of the ordinary and extraordinary beams, the birefringence An, is zero along the optical axis (the crystallophysical axis Z) and maximum in a direction normal to this axis. The refractive index for the ordinary beam does not depend on the direction of propagation. However, the refractive index for the extraordinary beam n (6>), is a function of the polar angle 6 between the Z axis and the vector k ... [Pg.826]

A convenient way to attain a very high degree of linear polarization is to use prisms made of the birefringent material calcite (CaCOs). The arrangements in Glan-Taylor and Glan-Thompson polarizers are shown in Fig. 6.46. Both these polarizers consist of a combination of two prisms, in the first type air-spaced, in the second case cemented. The prism angle has been chosen such that the ordinary beam is totally internally reflected and absorbed laterally in the prism, while the extraordinary beam is transmitted into the... [Pg.141]

A nematic liquid crystal with a uniform alignment of the director n behaves like a uniaxial crystal with positive optical anisotropy > <, (where He = i is the refraction index for the extraordinary beam and <, = is the refraction index for the ordinary beam). We can consider the cholesteric structure as a special case of a nematic structure when the director n describes a helix. As is shown in Figure 6.1, the optical anisotropy in CLCs is negative, i.e., rioh > K /i, where tiei, = np and n h = xa are the refractive indices for the extraordinary and ordinary beams, respectively. The index h indicates that the macroscopic optical axis corresponds to the direction of... [Pg.162]

Because the electric vector of the light has components normal to the beam, in anisotropic materials they feel different electronic polarizabilities, i.e., different refractive indices. For this reason, the speed of the light of different polarization directions will be different Vo = c/n describes the speed of the "ordinary" wave, and Ve = c/n relates to the "extraordinary" beam, which exists only in anisotropic materials. Due to the differences of the speeds, there will be a phase difference between the ordinary and extraordinary vvaves. Since the wavevector k of the light relates to the wavelength, X as k =k = n = n-, the difference between the phases (the so called retardation) of the ordinary and extraordinary waved can be expressed as ... [Pg.161]

The elementary Lyot filter consists of a birefringent crystal placed between two linear polarizers (Fig.4.55). Assume that the two polarizers are both parallel to the electric vector E(0) of the incoming wave. Let the crystal with length L be placed between x = 0 and x = L. Because of the different refractive indices nQ and n for the ordinary and the extraordinary beams, the two partial waves at x = L,... [Pg.177]

In the crystals described there are one or two directions along which the double refraction does not occur. These directions are referred to as the optical axes of a crystal (in Figure 6.26 and further defined by line MN). Certainly, they are determined by the atomic stracture of a crystal. If the crystal has one such direction it is referred to as a single-axis crystal there are also biaxial crystals with two such directions. Any plane which runs through the crystal s optical axis is referred to as the main section or the main plane. Most interesting is the main section containing the light beam. The plane of the vector E oscillations in an ordinary beam is perpendicular to the main section and in extraordinary beam lies in the main plane. [Pg.391]


See other pages where Extraordinary beam is mentioned: [Pg.681]    [Pg.20]    [Pg.495]    [Pg.219]    [Pg.220]    [Pg.458]    [Pg.470]    [Pg.328]    [Pg.476]    [Pg.420]    [Pg.157]    [Pg.826]    [Pg.33]    [Pg.435]    [Pg.183]    [Pg.744]    [Pg.165]    [Pg.826]    [Pg.159]    [Pg.160]    [Pg.177]    [Pg.181]    [Pg.391]    [Pg.393]    [Pg.393]   
See also in sourсe #XX -- [ Pg.141 ]




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