scholarly journals Fine structure of perturbed Laguerre–Gaussian beams: Hermite–Gaussian mode spectra and topological charge

2020 ◽  
Vol 59 (25) ◽  
pp. 7680 ◽  
Author(s):  
A. Volyar ◽  
E. Abramochkin ◽  
Yu. Egorov ◽  
M. Bretsko ◽  
Ya. Akimova
Keyword(s):  
Fine Structure ◽  
Topological Charge ◽  
Gaussian Beams ◽  
Gaussian Mode

scholarly journals Coaxial propagation of Laguerre–Gaussian (LG) and Gaussian beams in a plasma

2015 ◽  
Vol 33 (1) ◽  
pp. 123-133 ◽  
Author(s):  
Shikha Misra ◽  
Sanjay K. Mishra ◽  
P. Brijesh
Keyword(s):  
Beam Width ◽  
Phase Evolution ◽  
Spot Size ◽  
Spatial Soliton ◽  
Gaussian Beams ◽  
Mode Propagation ◽  
Intensity Maximum ◽  
Coupled Mode ◽  
Non Linear ◽  
Gaussian Mode

AbstractThis paper investigates the non-linear coaxial (or coupled mode) propagation of Laguerre–Gaussian (LG) (in particular L01 mode) and Gaussian electromagnetic (em) beams in a homogeneous plasma characterized by ponderomotive and relativistic non-linearities. The formulation is based on numerical solution of non-linear Schrödinger wave equation under Jeffreys–Wentzel–Kramers–Brillouin approximation, followed by paraxial approach applicable in the vicinity of intensity maximum of the beams. A set of coupled differential equations for spot size (beam width) and phase evolution with space corresponding to coupled mode has been derived and numerically solved to determine the propagation dynamics. Using focusing equation a critical condition describing the self-trapped (i.e., spatial soliton) mode of laser beam propagation in the plasma has been discussed; as a consequence oscillatory focusing/defocusing of the beams in coupled mode propagation have been analyzed and presented graphically. As an important outcome, significant enhancement in the intensity of LG beam is noticed when it is coupled with the Gaussian mode.

scholarly journals Sorting Laguerre-Gaussian beams by radial numbers via intensity moments

2020 ◽  
Vol 44 (2) ◽  
pp. 155-166
Author(s):  
A.V. Volyar ◽  
M. Bretsko ◽  
Ya. Akimova ◽  
Yu. Egorov
Keyword(s):  
Spectral Line ◽  
Information Entropy ◽  
Topological Charge ◽  
Amplitude Spectrum ◽  
Gaussian Beams ◽  
Digital Analysis ◽  
Correlation Degree ◽  
Amplitude Spectra ◽  
A New Technique ◽  
Measure Of Uncertainty

We propose and experimentally implement a new technique for digitally sorting Laguerre-Gaussian (LG) modes by radial number at a constant topological charge, resulting from the pertur-bation of the original LG beam, or superposition thereof, by passing them through a thin dielectric diaphragm with various aperture radii. The technique is based on a digital analysis of higher-order intensity moments. Two types of perturbed beams are considered: non-degenerate and degenerate beams with respect to the initial radial number of the LG beam superposition. A diaphragm with a circular pinhole causes the appearance of a set of secondary LG modes with different radial num-bers, which are characterized by an amplitude spectrum. The digital amplitude spectrum makes it possible to recover the real LG modes and find the measure of uncertainty due to perturbation by means of information entropy. It is found that the perturbation of a complex beam leads to the appearance of a degenerate am-plitude spectrum since a single spectral line corresponds to a set of modes generated by M original Laguerre-Gaussian beams with different radial numbers. For the spectrum to be deciphered, we use M keys represented by the amplitude spectra of the nondegenerate perturbed beams in our ex-periment. However, the correlation degree decreases to 0.92.

Oriented Gaussian beams for high-accuracy computation with accuracy control of X-ray propagation through a multi-lens system

2019 ◽  
Vol 26 (2) ◽  
pp. 363-372
Author(s):  
P. Wojda ◽  
S. Kshevetskii
Keyword(s):  
Fine Structure ◽  
Electric Field ◽  
Focal Plane ◽  
Accurate Method ◽  
Gaussian Beams ◽  
X Rays ◽  
Accuracy Control ◽  
X Ray ◽  
Local Direction

A highly accurate method for calculating X-ray propagation is developed. Within this approach, the propagating wave is represented as a superposition of oriented Gaussian beams. The direction of wave propagation in each Gaussian beam agrees with the local direction of propagation of the X-ray wavefront. When calculating the propagation of X-ray waves through lenses, the thin lens approximation is applied. In this approximation, the wave parameters change discontinuously when the wave passes through a lens; the corresponding explicit formulae are derived. The theory is applied to highly accurate calculation of the focusing of X-rays by a system of many beryllium lenses. Fine structure of the wave electric field on the focal plane is revealed and studied. The fine structure is formed due to the diffraction of waves at the edges of the lens apertures. Tools for controlling the calculation accuracy are proposed. The amplitude of the electric field on the focal plane and the focal spot width are shown to be very sensitive to the quality of the calculation, while the best focus position can be obtained even from simple calculations.

scholarly journals Topological charge of two parallel Laguerre-Gaussian beams

2021 ◽  
Author(s):  
Victor Kotlyar ◽  
Alexey Kovalev ◽  
POURIA AMIRI ◽  
Peyman Soltani ◽  
Saifollah Rasouli
Keyword(s):  
Topological Charge ◽  
Gaussian Beams

Fine Structure of Platelet Interaction with a New Microcrystalline Collagen Preparation

1974 ◽  
Vol 32 ◽  
pp. 58-59
Author(s):  
W. H. Zucker ◽  
R. G. Mason
Keyword(s):  
Fine Structure ◽  
Platelet Aggregation ◽  
Hydrochloric Acid ◽  
Whole Blood ◽  
Platelet Adhesion ◽  
Hemostatic Agent ◽  
Native Collagen ◽  
Fibrillar Morphology ◽  
Clinical Interest ◽  
New Form

Platelet adhesion initiates platelet aggregation and is an important component of the hemostatic process. Since the development of a new form of collagen as a topical hemostatic agent is of both basic and clinical interest, an ultrastructural and hematologic study of the interaction of platelets with the microcrystalline collagen preparation was undertaken.In this study, whole blood anticoagulated with EDTA was used in order to inhibit aggregation and permit study of platelet adhesion to collagen as an isolated event. The microcrystalline collagen was prepared from bovine dermal corium; milling was with sharp blades. The preparation consists of partial hydrochloric acid amine collagen salts and retains much of the fibrillar morphology of native collagen.

Pituitary Follicular Cells: Their Origin, Possible Function and Fate

1974 ◽  
Vol 32 ◽  
pp. 34-35
Author(s):  
E. Horvath ◽  
K. Kovacs ◽  
G. Penz ◽  
C. Ezrin
Keyword(s):  
Fine Structure ◽  
Secretory Granules ◽  
Follicular Cells ◽  
Human Pituitary ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Junctional Complexes

Follicular structures, in the rat pituitary, composed of cells joined by junctional complexes and possessing few organelles and few, if any, secretory granules, were first described by Farquhar in 1957. Cells of the same description have since been observed in several species including man. The importance of these cells, however, remains obscure. While studying human pituitary glands, we have observed wide variations in the fine structure of follicular cells which may lead to a better understanding of their morphogenesis and significance.

Ultrastructure and Staining of Developing Elastic Tissue

1971 ◽  
Vol 29 ◽  
pp. 244-245
Author(s):  
E. N. Albert
Keyword(s):  
Fine Structure ◽  
Phosphotungstic Acid ◽  
Staining Method ◽  
Rat Aorta ◽  
Uranyl Acetate ◽  
The Other ◽  
Elastic Fibers ◽  
Elastic Tissue ◽  
Lead Citrate ◽  
New Born

Silver tetraphenylporphine sulfonate (Ag-TPPS) was synthesized in this laboratory and used as an electron dense stain for elastic tissue (Fig 1). The procedures for the synthesis of tetraphenylporphine sulfonate and the staining method for mature elastic tissue have been described previously.The fine structure of developing elastic tissue was observed in fetal and new born rat aorta using tetraphenylporphine sulfonate, phosphotungstic acid, uranyl acetate and lead citrate. The newly forming elastica consisted of two morphologically distinct components. These were a central amorphous and a peripheral fibrous. The ratio of the central amorphous and the peripheral fibrillar portion changed in favor of the former with increasing age.It was also observed that the staining properties of the two components were entirely different. The peripheral fibrous component stained with uranyl acetate and/or lead citrate while the central amorphous portion demonstrated no affinity for these stains. On the other hand, the central amorphous portion of developing elastic fibers stained vigorously with silver tetraphenylporphine sulfonate, while the fibrillar part did not (compare figs 2, 3, 4). Based upon the above observations it is proposed that developing elastica consists of two components that are morphologically and chemically different.

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