Phenomenon Of Double Refraction Research Articles

Physical, Thermal and Biological Properties of Yellow Dyes with Two Azodiphenylether Groups of Anthracene.

Two yellow bis-azo dyes containing anthracene and two azodiphenylether groups (BPA and BTA) were prepared, and an extensive investigation of their physical, thermal and biological properties was carried out. The chemical structure was confirmed by the FTIR spectra, while from the UV–Vis spectra, the quantum efficiency of the laser fluorescence at the 476.5 nm was determined to be 0.33 (BPA) and 0.50 (BTA). The possible transitions between the energy levels of the electrons of the chemical elements were established, identifying the energies and the electronic configurations of the levels of transition. Both crystals are anisotropic, the optical phenomenon of double refraction of polarized light (birefringence) taking place. Images of maximum illumination and extinction were recorded when the crystals of the bis-azo compounds rotated by 90° each, which confirms their birefringence. A morphologic study of the thin films deposited onto glass surfaces was performed, proving the good adhesion of both dyes. By thermal analysis and calorimetry, the melting temperatures were determined (~224–225 °C for both of them), as well as their decomposition pathways and thermal effects (enthalpy variations during undergoing processes); thus, good thermal stability was exhibited. The interaction of the two compounds with collagen in the suede was studied, as well as their antioxidant activity, advocating for good chemical stability and potential to be safely used as coloring agents in the food industry.

Dynamics of Light Induced Reorientation of Nematic Liquid Crystals in Spatially Confined Beams

Optically induced reorientation dynamics in a nematic liquid crystal is investigated for circularly polarized laser beams with spot sizes smaller than the sample thickness. Various dynamical regimes, such as periodic, quasi-periodic, intermittent, self-organized and possibly chaotic regimes are observed. The role finite beam size is identified and a qualitative interpretation based on the spatial walk-off of the ordinary and extraordinary beams arising from double refraction phenomenon is proposed.

DOUBLE REFRACTION PHENOMENON OF ELECTRORHOLOGICAL FLUIDS

In this paper, the adjustable double refraction phenomenon of Electrorhological fluids (ERF) was investigated. The measurements have been made of He-Ne laser through suspension of silica and pentaerythrite in silicone oil. When electric field was applied perpendicular to the laser beam, it was found that no light gets through the pair of perpendicular polarizing plate and analyzer plate without electric field. But when ERF is brought to bear electric field, the transmission light intensity increases with the electric field to be rising. For ERF of the same material, the double refraction phenomenon is more obviously to the low concentration. It is thought that the double refraction phenomenon of ERF is due to the fact that the particles link together to form thin chains or thick columns.

The measurement of complex permittivity of anisotropic dielectrics by means of an electromagnetic open resonator

By applying the perturbation method and the complex-source-point theory, the theoretical research of measurement of complex permittivity of uniaxial anisotropic materials by means of an electromagnetic open resonator has been made, and the double refraction phenomenon due to anisotropy of measured dielectric materials has been quantitatively analyzed. Finally, measurements have been made on some single-crystal quartz specimens using an automated open resonator measurement system at 8mm band.

Double refraction near a rough bottom in isothermal waters

The occurence of a boundary wave during low‐frequency grazing scatter from rough rigid surfaces has been described by Tolstoy and experimentally verified by Medwin et al. [J. Acoust. Soc. Am. 66, 1131–1134 (1979)] for a homogeneous medium overlying the surface. Tolstoy [J. Acoust. Soc. Am. 69, 1290–1298 (1981)] has also shown that, when the velocity in the medium decreases away from the ocean bottom, tunneling into the shadow zone takes place, for source and receiver on the bottom. We re‐examine this case but for the source and receiver near the ocean surface and for bottoms of lesser roughness. It is predicted that, under certain conditions of velocity gradient, frequency, and bottom roughness, the boundary wave mode causes a splitting of the limiting ray above the rough bottom. As a result, two refracted rays would reach the ocean surface: a primary ray (classical limiting ray for smooth bottom), and a secondary ray with a significantly greater skip distance. This double refraction phenomenon should be detectable at sea, under suitable experimental conditions. [Research supported by ONR.]

Double Refraction on Optical Second Harmonic in Thin Crystals

THE first observations of second harmonic generation of light (SHG) were made with a high-power pulsed ruby laser. Since then these nonlinear effects have been successfully observed with continuous wave He–Ne gas lasers1. Recently, the so-called aperture effect of SHG, which had been predicted2 and which is equivalent to the familiar phenomenon of double refraction, was experimentally observed3 in long crystals (of length 5 to 10 cm). We report here that SHG double refraction has been detected in thin crystals 1 mm to 2 mm thick, using as an input beam the light from a gas laser.

Dispersion for Double Refraction in Electron Diffraction by Magnesium Oxide Crystal

Fourier potentials, or Fourier coefficients of the periodic potential in a crystal, may be determined through the double refraction phenomenon of electrons by crystal wedges. The values of Fourier potentials V 000 and V 220 of MgO for the electron energy range 20∼300 keV were obtained by the measurements of (220) refraction multiplets in electron diffraction patterns given from smoke samples. It is expected that the experimentally obtained Fourier potentials are accompanied by an energy dependence by influence of the additional dispersion terms which were theoretlcally introduced by Yoshioka. In the present study, it is found that the values of the experimental Fourier potentials, obtained with the due relativistic correction, show a change with electron energy, but the change does not behave in proportion to λ(1+ h 2 / m 0 2 c 2 λ 2 ) 1/2 as required by the relations calculated by Yoshioka, where λ is the electron wave-length, m 0 , the rest mass of electron, h , Planck constant, and c , the light velocity.

Dynamic-Photostress Analysis of Velocity Transformers

Certain transparent materials and certain strained plastics demonstrate the phenomenon of double refraction or birefringence. They divide an incident ray of light into two beams which travel at different speeds through the material. This means that one beam will be retarded in relation to the other while traveling through the plastic. In addition, the two beams transmitted through the doubly refractive materials are polarized at right angles to each other. The direction of polarization corresponds to the direction of principal strains or stress in the materials. These materials make the stress visible as colored fringe patterns. With the aid of this technique, the stress distribution and particle amplitude on four types of help wavelength velocity transformers (namely stepped, conical, exponential, and calenoidal) were observed and photographed. These experimental results were compared to those calculated from theory.

Ultrasonic Double Refraction in Worked Metals

In the first part of this work the double refraction observed while measuring the attenuation of ultrasonic transverse waves in heat-treated 4150 steel was investigated. Although the data are not complete, they suggest that this double refraction phenomenon can be utilized to detect the amount of preferred orientation of the crystallites in rolled steel when this orientation is small. Calculated values of fractional velocity differences are given. In the second part the theory of ultrasonic wave propagation in polycrystalline metal is discussed, and the effect of preferential orientation of crystallites on fractional velocity changes is indicated. The use of ultrasonic double refraction data for determining the extent of preferential orientation is discussed.

The Kerr Effect in Optically Active Liquids

WHEN polarised light passes through an optically active liquid in an electrostatic or a magnetic field the phenomenon of double refraction observed with a non-active substance is complicated by the optical rotation, and the only method employed to study the birefringence has been to mix equal quantities of right- and left-handed samples of the compound to be investigated, so as to obtain a non-active liquid.. M. R. de Mallemann, in the Annales de Physique for July-August, making use of the Airy-Gouy principle that on the element of path dl the double refraction and the rotation act independently of one another, and that the resultant effect can be calculated by compounding the elementary vectors representing the two effects, derives formulae by means of which the true double refraction of the liquid can be derived from the observations. Measurements are described on pinene, turpentine, ethyl tartrate, carvone and camphor, in which Panthener's method of instantaneous charge was used, which, in spite of certain difficulties, gives fairly satisfactory results in all cases, and enables the birefringence of imperfect insulators to be determined. I

Memoirs: Engelmann on Contractility and Double Refraction

ABSTRACT After referring to Boeck’s original discovery of the phenomenon of double refraction in muscles, and to Brücke’s classical memoir, Engelmann states that in spite of proofs being brought forward of the association of other forms of contractile phenomena with the presence of double refraction, e. g. in the muscles of certain infusoria, the results were almost all negative. In consequence, the opinion prevailed that the presence of anisotropous elements in muscle was a curious rather than an important phenomenon. This point of view was modified when it was shown by Engelmann himself (Pflüger’s ‘Archiv,’ Bd. 7) that contraction is exclusively connected with the double-refracting layers in striped muscle. The supposition then arose that, as a general law, contraction might be dependent on the presence of double-refracting particles, especially as the boundaries between different forms of movement in protoplasm and in muscle formerly assumed to be so sharply defined had broken down.

XXV.—Experiments on the Ordinary Refraction of Iceland Spar

According to the theory devised by Huygens, to explain the phenomenon of double refraction in Iceland spar, a pencil of light transmitted through that substance is divided into two pencils; the index of refraction for the one being constant, while for the other it varies with the inclination of the transmitted light to the optical axis of the crystal.Dr Wollaston, in 1802, verified the spheroidal form of the wave of light, which Huygens had assumed to account for the refraction of the extraordinary pencil, by a careful experimental investigation, conducted by means of his elegant instrument for “examining refractive and dispersive powers by prismatic reflection.” In 1810, Malus, in his Théorie de la Double Réfraction, also demonstrated experimentally the accuracy of the Huygenian law for the extraordinary pencil. I have not had an opportunity of consulting the memoir of Malus, so as to know the precise nature of his experiments, with reference to the refraction of the ordinary ray; but the object of Dr Wollaston's researches was simply to prove the law of extraordinary refraction, and the constancy of the index of refraction for the ordinary ray, is therefore tacitly assumed by him.

On the methods of cutting rock crystal for micrometers

For the purpose of examining the phenomenon of double refraction, it is easy to combine a wedge of rock crystal with one of crown glass, so that a luminous object seen through them shall appear in its true place by ordinary refraction, accompanied by a second image produced by extraordinary refraction. In consequence of the dispersion of colours which occurs in employing different substances, such a combination is not suited for the micrometer invented by Abbé Rochon; but it is not difficult to obtain such a section of rock-crystal as may be substituted for the glass wedge, so that the pencil of light shall be colourless without diminishing the separation of the images. But since the degree to which the double refraction of rock crystal separates the two portions of a beam of light transmitted through it, is sometimes not sufficiently great, it becomes desirable to increase it; and though the means of effecting this have not been described, the author proceeds to explain the method that he has found advantageous, and which he regards the same as that of M. Rochon.