scholarly journals Simple and Efficient Realization of Transverse Linear Dark Beams by Azimuthal Phase-Shifted Square Zone Plate

2021 ◽  
Author(s):  
Shahrbanoo Asghari ◽  
Arash Sabatyan
Keyword(s):  
Grating Period ◽  
Experimental Results ◽  
Zone Plate ◽  
Dark Line ◽  
Dark Zone ◽  
Straightforward Method ◽  
Diffractive Element ◽  
Efficient Realization

Abstract Herein, we are about to introduce a novel, reliable and straightforward method to create controllable dark lines employing an azimuthal square zone plate. As a matter of fact, this diffractive element is a square zone plate whose zones are phase-shifted azimuthally. As we illustrate, one way to construct it is combining a square zone plate and radial grating having period m. Considering its focusing behavior, we came to the result that a dark line surrounded by linear bright zones is generated for odd m, as well as a cross-like dark zone is produced when m is even. Furthermore, we illustrate that the length of the dark lines depends on the grating period. Finally, the simulation predictions are verified by experimental results.

Méthode du moment angulaire inversé. Partie II : Application aux problèmes hyperfins diatomiques

1975 ◽  
Vol 53 (5) ◽  
pp. 542-552 ◽  
Author(s):  
J-L. Féménias ◽  
C. Athénour
Keyword(s):  
Angular Momentum ◽  
Experimental Verification ◽  
Experimental Results ◽  
Matrix Elements ◽  
Intensity Factors ◽  
Method Of Calculation ◽  
Straightforward Method ◽  
Mi Theory

We present a straightforward method of calculation in rotational molecular problems based on the theory of reversed angular momentum (MI theory) previously discussed. After some general remarks and calculations, we test this method by calculating some well known hyperfine matrix elements in diatomic problems, showing thus its easy handling. The first experimental verification relative to intensity factors in hyperfine diatomic transitions that the method enabled us to calculate, is presented with a brief survey of the recent experimental results obtained from the analysis of the [Formula: see text] system of NbN.

DOUBLE PHASE CONJUGATE MIRROR AT 1.55 μm BETWEEN SINGLE MODE FIBERS WITH CdZnTe: V

1996 ◽  
Vol 05 (03) ◽  
pp. 603-610
Author(s):  
G. MARTEL ◽  
N. WOLFFER ◽  
J.Y. MOISAN ◽  
P. GRAVEY
Keyword(s):  
Piezoelectric Effect ◽  
Coupling Efficiency ◽  
Single Mode ◽  
Grating Period ◽  
Experimental Results ◽  
Beam Direction ◽  
Phase Conjugate ◽  
Double Phase ◽  
Experimental Parameters ◽  
Phase Conjugate Mirror

We present experimental results of a double phase conjugate mirror (DPCM) in a crystal of Cd 0.96 Zn 0.04 Te:V operating at 1.55 μm. Elimination of conical diffraction has been obtained by cylindrical lenses and has allowed to measure a coupling efficiency between monomode fibers versus different experimental parameters. An oscillation of the diffracted beam direction at the frequency of the applied ac field has been observed. Perturbation of the grating period that satisfy the Bragg matching can be due to mechanical vibrations resulting from the piezoelectric effect. In a ring phase conjugate mirror (PCM) configuration, experimental results of the conversion efficiency and of the phase of the diffracted beam are also presented.

Experimental and Numerical Investigation of a Semispherical Solar Still, Chamber Stepwise Basin, with and without a PV Powered Electrical Heater

2022 ◽  
pp. 1-17
Author(s):  
Safa M Aldarabseh ◽  
Salah Abdallah
Keyword(s):  
Saline Water ◽  
Pure Water ◽  
Power Source ◽  
Experimental Results ◽  
Solar Still ◽  
Electrical Heater ◽  
Straightforward Method ◽  
Solar Intensity ◽  
Rate Of Evaporation ◽  
Mathcad Software

Abstract The world's need for drinkable water is increasing with a growing population. The desalination process using solar energy is the cheapest and most straightforward method that can be used to generate pure water from saline water by utilizing energy from the sun's free heat source. A semispherical and chamber stepwise basin solar still with an inclined glass cover, with and without PV powered electrical heaters as another power source can increase the rate of evaporation of saline water, thus increasing the productivity of semispherical solar still. In this investigation, a conventional solar still and semispherical solar still with and without PV-powered electrical heaters were invented and worked in parallel with the experimental setup to make a good comparison between these models. The experimental results show that stepped semispherical with PV-powered electrical heater and without PV-powered electrical heater solar stills enhanced the productivity of freshwater from a conventional solar still by 156.6% and 72.5%, respectively. The theoretically simulated model is obtained using Mathcad software, and is compared with experimental results. Semispherical solar still productivity increases with increased solar intensity and with a PV-powered electrical heater as an additional power source. The theoretical results concluded from the mathematical model are in good agreement with experimental results.

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

Observation of Phase Contrast Images in STEM and CTEM Modes by Using 100 kV Field Emission Electron Gun

1974 ◽  
Vol 32 ◽  
pp. 390-391
Author(s):  
Y. Harada ◽  
T. Goto ◽  
H. Koike ◽  
T. Someya
Keyword(s):  
Field Emission ◽  
Phase Contrast ◽  
Image Formation ◽  
Fresnel Diffraction ◽  
Experimental Results ◽  
Electron Gun ◽  
Scanning Microscopy ◽  
Emission Electron ◽  
Lattice Images

Since phase contrasts of STEM images, that is, Fresnel diffraction fringes or lattice images, manifest themselves in field emission scanning microscopy, the mechanism for image formation in the STEM mode has been investigated and compared with that in CTEM mode, resulting in the theory of reciprocity. It reveals that contrast in STEM images exhibits the same properties as contrast in CTEM images. However, it appears that the validity of the reciprocity theory, especially on the details of phase contrast, has not yet been fully proven by the experiments. In this work, we shall investigate the phase contrast images obtained in both the STEM and CTEM modes of a field emission microscope (100kV), and evaluate the validity of the reciprocity theory by comparing the experimental results.

A new dissociation mode for dislocations in silicon

1978 ◽  
Vol 36 (1) ◽  
pp. 346-347
Author(s):  
A. Ourmazd ◽  
G.R. Booker ◽  
C.J. Humphreys
Keyword(s):  
Detailed Examination ◽  
Experimental Results ◽  
Dislocation Network ◽  
Weak Beam ◽  
Phosphorus Doped

A (111) phosphorus-doped Si specimen, thinned to give a TEM foil of thickness ∼ 150nm, contained a dislocation network lying on the (111) plane. The dislocation lines were along the three <211> directions and their total Burgers vectors,ḇt, were of the type , each dislocation being of edge character. TEM examination under proper weak-beam conditions seemed initially to show the standard contrast behaviour for such dislocations, indicating some dislocation segments were undissociated (contrast A), while other segments were dissociated to give two Shockley partials separated by approximately 6nm (contrast B) . A more detailed examination, however, revealed that some segments exhibited a third and anomalous contrast behaviour (contrast C), interpreted here as being due to a new dissociation not previously reported. Experimental results obtained for a dislocation along [211] with for the six <220> type reflections using (g,5g) weak-beam conditions are summarised in the table below, together with the relevant values.

Imaging nanostructures on ablated kapton polymide

1993 ◽  
Vol 51 ◽  
pp. 872-873
Author(s):  
Daniel L. Callahan ◽  
H. M. Phillips ◽  
R. Sauerbrey
Keyword(s):  
Electron Microscopy ◽  
Polymer Surface ◽  
Grating Period ◽  
Laser Wavelength ◽  
Integrated Devices ◽  
Transmission Electron ◽  
Excimer Laser Irradiation ◽  
Produce Line ◽  
Line Patterns ◽  
Anisotropic Conduction

Excimer laser irradiation has been used to interferometrically ablate submicron line patterns on to Kapton polyimide. Such patterned material may exhibit highly anisotropic conduction as was predicted from previous studies showing enhanced conductivity from uniformly ablated material. We are currently exploiting this phenomenon to create integrated devices using conventional polymers as both dielectrics and conductors. Extensive scanning electron microscopy (SEM) and limited transmission electron microscopy (TEM) have been conducted in order to characterize the morphology of such patterned nanostructures as a function of processing conditions.The ablation technique employed produces an interference pattern on the polymer surface of period equal to half that of a diffraction grating period, independent of the laser wavelength. In these experiments, a 328 nm grating has been used to produce line patterns of 164 nm line-spacings as shown in Figures 1 and 2. A 200 Å Au coating has been used to both prevent charging and, perhaps more importantly, enhance contrast.

Multislice calculations of RHEED patterns from vicinal Si (001)

1993 ◽  
Vol 51 ◽  
pp. 1000-1001
Author(s):  
Scott Lordi
Keyword(s):  
Misorientation Angle ◽  
Incident Angle ◽  
Incident Beam ◽  
Experimental Results ◽  
Bragg Condition ◽  
Vicinal Surfaces ◽  
Kinematic Theory ◽  
Step Edges

Vicinal Si (001) surfaces are interesting because they are good substrates for the growth of III-V semiconductors. Spots in RHEED patterns from vicinal surfaces are split due to scattering from ordered step arrays and this splitting can be used to determine the misorientation angle, using kinematic arguments. Kinematic theory is generally regarded to be inadequate for the calculation of RHEED intensities; however, only a few dynamical RHEED simulations have been attempted for vicinal surfaces. The multislice formulation of Cowley and Moodie with a recently developed edge patching method was used to calculate RHEED patterns from vicinal Si (001) surfaces. The calculated patterns are qualitatively similar to published experimental results and the positions of the split spots quantitatively agree with kinematic calculations.RHEED patterns were calculated for unreconstructed (bulk terminated) Si (001) surfaces misoriented towards [110] ,with an energy of 15 keV, at an incident angle of 36.63 mrad ([004] bragg condition), and a beam azimuth of [110] (perpendicular to the step edges) and the incident beam pointed down the step staircase.

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