Characteristic Parameters of a Beam with a Gaussian Irradiance Distribution

1972 ◽  
Vol 50 (3) ◽  
pp. 301-302 ◽  
Author(s):  
John W. Y. Lit ◽  
Russell Boulay
Keyword(s):  
Beam Waist ◽  
Beam Axis ◽  
Circular Aperture ◽  
Characteristic Parameters ◽  
Simple Method ◽  
Optical Wave ◽  
Diffraction Wave

This describes a simple method to find two important characteristic parameters of a beam with a Gaussian irradiance profile—the position of the plane of the beam waist and the value of ω0 in that plane. It is necessary to observe the positions of maximum or minimum irradiances along the beam axis in the field diffracted by a circular aperture. These positions occur at places where the direct geometric-optical wave is in phase or out of phase with the boundary-diffraction wave.

Field of a Truncated Gaussian Beam as Given by the Boundary-Diffraction-Wave Theory

1972 ◽  
Vol 50 (3) ◽  
pp. 259-263 ◽  
Author(s):  
Russell Boulay ◽  
John W. Y. Lit
Keyword(s):  
Gaussian Beam ◽  
Incident Wave ◽  
Wave Theory ◽  
Numerical Results ◽  
Circular Aperture ◽  
Diffraction Wave ◽  
Kirchhoff Integral ◽  
Truncated Gaussian ◽  
Good Agreement

The field of an incident wave with a Gaussian irradiance distribution diffracted by a circular aperture has been evaluated by using the boundary-diffraction-wave theory. Numerical results of the irradiance distributions, both along the axis and in transverse planes, are compared with those given by the Kirchhoff integral. Good agreement is obtained in all cases over wide regions of the diffracted field.

A NOTE ON THE DIFFRACTION OF A SCALAR WAVE BY A SMALL CIRCULAR APERTURE

1961 ◽  
Vol 39 (7) ◽  
pp. 1065-1070 ◽  
Author(s):  
R. A. Hurd
Keyword(s):  
Power Series ◽  
Plane Wave ◽  
Transmission Coefficient ◽  
Series Solution ◽  
Recurrence Relations ◽  
Power Series Solution ◽  
Circular Aperture ◽  
Scalar Wave ◽  
Simple Method ◽  
Plane Wave Incident

The power series solution for the diffraction of a scalar plane wave incident normally on a small circular aperture in a hard screen is extended to include terms of order α12 in the aperture field, and to terms of order α10 in the transmission coefficient (α = 2π × radius of aperture/wavelength). To do this, a set of recurrence relations is developed, and a relatively simple method of obtaining the transmission coefficient is devised.

scholarly journals Characteristic parameters of optical wave and short-term beam spreading in oceanic turbulence

2018 ◽  
Vol 67 (22) ◽  
pp. 224206
Author(s):  
Wu Tong ◽  
Ji Xiao-Ling ◽  
Li Xiao-Qing ◽  
Wang Huan ◽  
Deng Yu ◽  
...  
Keyword(s):  
Characteristic Parameters ◽  
Short Term ◽  
Optical Wave ◽  
Beam Spreading ◽  
Oceanic Turbulence

MTU Laser-Based Direct-Write Techniques: Recent Development and Nanoparticles Patterning Results

2002 ◽  
Vol 758 ◽  
Author(s):  
Edward M. Nadgorny ◽  
Changgong Zhou ◽  
Jaroslaw Drelich ◽  
Randy Zahn
Keyword(s):  
Beam Waist ◽  
Laser Beams ◽  
Direct Write ◽  
Circular Aperture ◽  
Computational Results ◽  
Waist Size ◽  
Liquid Precursors ◽  
Gold Thiolate ◽  
Liquid Suspensions ◽  
Fraunhofer Approximation

ABSTRACTTwo laser-based direct-write techniques to guide particles from a mist source to a target substrate by laser beams were recently developed at Michigan Tech. The laser-guided direct-write (LGDW) technique uses a hollow optical fiber, while the laser-guided microsensor patterning (LGMP) technique uses a micrometer-sized aperture. The techniques are suggested to be utilized for patterning microstructures made of nanoparticles that are either crystallized from liquid precursors or directly deposited from nanoparticle-in-liquid suspensions. The computational results based on the paraxial Fraunhofer approximation of a Gaussian beam diffracted by a circular aperture and experimental measurements of corresponding deposition rate under different conditions suggest several factors for setup optimization of LGMP. The results indicate that among the most important factors are the aperture size relative to the laser beam-waist size and the divergence of the beam near the aperture. Examples of gold-thiolate, protein-coated polystyrene, and carbon-polymer composites deposition are presented.

Siphon Flows in Stratified Coronal Loops

1994 ◽  
Vol 144 ◽  
pp. 185-187
Author(s):  
S. Orlando ◽  
G. Peres ◽  
S. Serio
Keyword(s):  
Heat Flux ◽  
Scaling Laws ◽  
Flow Model ◽  
Supersonic Flows ◽  
Coronal Loops ◽  
Characteristic Parameters

AbstractWe have developed a detailed siphon flow model for coronal loops. We find scaling laws relating the characteristic parameters of the loop, explore systematically the space of solutions and show that supersonic flows are impossible for realistic values of heat flux at the base of the upflowing leg.

Axial Observation of X-Ray Spectra from a Beam-Foil Source

1988 ◽  
Vol 102 ◽  
pp. 339-342
Author(s):  
J.M. Laming ◽  
J.D. Silver ◽  
R. Barnsley ◽  
J. Dunn ◽  
K.D. Evans ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
Heavy Ion ◽  
Ion Beams ◽  
Beam Axis ◽  
Doppler Broadening ◽  
X Ray ◽  
Beam Foil

AbstractNew observations of x-ray spectra from foil-excited heavy ion beams are reported. By observing the target in a direction along the beam axis, an improvement in spectral resolution, δλ/λ, by about a factor of two is achieved, due to the reduced Doppler broadening in this geometry.

A simple way for producing holographic filters suitable for image improvement

1978 ◽  
Vol 36 (1) ◽  
pp. 226-227
Author(s):  
K.-H. Herrmann ◽  
E. Reuber ◽  
P. Schiske
Keyword(s):  
Transfer Functions ◽  
Diffraction Order ◽  
Lateral Position ◽  
Simple Method ◽  
Spatial Frequencies ◽  
Resolution Electron ◽  
Wiener Filters ◽  
Image Improvement ◽  
Optical Reconstruction ◽  
Set Up

Aposteriori deblurring of high resolution electron micrographs of weak phase objects can be performed by holographic filters [1,2] which are arranged in the Fourier domain of a light-optical reconstruction set-up. According to the diffraction efficiency and the lateral position of the grating structure, the filters permit adjustment of the amplitudes and phases of the spatial frequencies in the image which is obtained in the first diffraction order.In the case of bright field imaging with axial illumination, the Contrast Transfer Functions (CTF) are oscillating, but real. For different imageforming conditions and several signal-to-noise ratios an extensive set of Wiener-filters should be available. A simple method of producing such filters by only photographic and mechanical means will be described here.A transparent master grating with 6.25 lines/mm and 160 mm diameter was produced by a high precision computer plotter. It is photographed through a rotating mask, plotted by a standard plotter.

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