L.G. Gasparyan

• PhD
• Senior Researcher at Yerevan State University

The influence of an external electric field on refractive indices of ordinary and extraordinary waves is investigated by means of the method of X-ray interferometry. The decrements of E7 type nematic liquid crystal were calculated for different values of external electric field strength and it was established that with increasing electric field str...

The influence of external electric field on the anisotropy of a layer of nematic liquid crystal (NLC) was investigated by means of X-Ray interferometric method. It was shown that in Xray range of the spectrum NLC E7 is a positive anisotropic medium. The decrements of a layer of NLC subjected to the electric field were calculated. As a result of reo...

The refractive index of nematic liquid crystal (NLC) E7 in the X-ray spectral range using the X-ray interferometric method, was measured experimentally. It was shown that NLC E7 is anisotropic medium for X-rays. This method is sensitive to reorientation of the molecules of liquid crystals and allows to measure the refractive index of homogeneously...

The anisotropy of 5CB type nematic liquid crystals was investigated by the X-ray interferometry method. The refractive indices n 0 and n e were determined and it was established that 5CB type nematic liquid crystals is X-ray optically positive anisotropic medium.

In the present work the X-ray optical anisotropy of 5CB type liquid crystals has been investigated based on the method of X-ray interferometry. In this way Moire fringes have been obtained both in the absence and presence of specimens with different orientations of optical axes. The relative displacement of Moire fringes enabled us to observe and i...

X-ray diffraction patterns obtained from a plane-parallel crystalline plate with a spherical cavity and from a wedge-shaped crystal have been investigated depending on the collimation of the primary incident beam. It is shown that in the case of ribbon-like incident beam the sectional topograms, obtained from the wedge-shaped crystal, have the form...

A new method for studying the X-ray optical anisotropy of materials which is based on the X-ray interferometric technique of measurement is described. Unlike the existing methods, in which the sample under study is placed in the path of one of the interfering beams, the test samples in the proposed method are placed directly in the path of two inte...

The effect of ultrasound artificial anisotropy of crystals in X-ray frequency range was observed and an effort to theoretically interpret this effect in Bragg-Laue diffraction case was made. It was established that an isotropic crystal optically turns into an artificially anisotropic one with optical axis along the direction of applied external inf...

The effect of artificial temperature anisotropy of crystals in X-ray frequency range was observed for the first time and an effort to theoretically interpret this effect in Bragg-Laue diffraction case was made. It was established that an isotropic crystal optically turns into an artificially anisotropic one with optical axis along the direction of...

A novel approach to the investigation of X-ray optical anisotropy of materials is proposed that is based on X-ray interferometric method of measurements. Unlike the existing methods, where the specimen to be tested is placed in the way of one of interfering beams, in the proposed approach the specimens under investigation are placed directly in the...

A novel approach to the investigation of X-ray optical anisotropy of materials is proposed that is based on X-ray interferometric method of measurements. Unlike the existing methods, where the specimen to be tested is placed in the way of one of interfering beams, in the proposed approach the specimens under investigation are placed directly in the...

The effect of artificial temperature anisotropy of crystals in X-ray frequency range was observed for the first time and an effort to theoretically interpret this effect in Bragg-Laue diffraction case was made. It was established that an isotropic crystal optically turns into an artificially anisotropic one with optical axis along the direction of...

The phenomenon of artificial temperature anisotropy has been observed at X-band frequencies and an attempt was made to give a theoretical explanation to this phenomenon in case of Bragg-Laue diffraction. The studies of this kind are important since in the Bragg case an anomalously transmitted beam may be used to examine interatomic lattice defects,...

Phenomenon of artificial ultrasound anisotropy is revealed in crystals in the range of X-ray frequencies and an attempt is made to explain this effect theoretically for the case of the Bragg-Laue diffraction. It is established that an isotropic crystal becomes, under action of ultrasound, optically anisotropic like a uniaxial crystal with the optic...

The Bragg-Laue diffraction in finite size crystal taking into account absorption effect is studied theoretically and experimentally. It is shown that besides the Bragg reflected wave the part of energy of diffracted wave penetrates inside the crystal and propagates with certain trajectory depending on the incident angle. In the case of point source...

The influence of dilatation and defocusing on interference lines obtained with LLL interferometers having different-thickness mirror blocks is studied both theoretically and experimentally. These interferens lines are known to be V-shaped. It is shown that the vertices of V-shaped bands are displaced along the diraction of the diffraction vector an...

The X-ray diffraction in interferometric systems consisting of mirror block parts having different thicknesses is investigated. By means of these systems, V-shaped interference patterns are obtained and they are shown to be due to rotations of reflecting planes when the mirror system has different thickness parts. With the change in sign of this di...