Techniques for accurately measuring laser beam width with commercial CCD cameras

1998 ◽  
Author(s):  
Carlos B. Roundy
Keyword(s):  
Laser Beam ◽  
Beam Width ◽  
Ccd Cameras

scholarly journals Self-Focusing of Hermite-Cosh-Gaussian Laser Beams in Plasma under Density Transition

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Manzoor Ahmad Wani ◽  
Niti Kant
Keyword(s):  
Laser Beam ◽  
Plasma Density ◽  
Focal Spot ◽  
Beam Width ◽  
Spot Size ◽  
Laser Beams ◽  
Equation Approach ◽  
Focal Spot Size ◽  
Self Focusing ◽  
Small Spot

Self-focusing of Hermite-Cosh-Gaussian (HChG) laser beam in plasma under density transition has been discussed here. The field distribution in the medium is expressed in terms of beam-width parameters and decentered parameter. The differential equations for the beam-width parameters are established by a parabolic wave equation approach under paraxial approximation. To overcome the defocusing, localized upward plasma density ramp is considered, so that the laser beam is focused on a small spot size. Plasma density ramp plays an important role in reducing the defocusing effect and maintaining the focal spot size up to several Rayleigh lengths. To discuss the nature of self-focusing, the behaviour of beam-width parameters with dimensionless distance of propagation for various values of decentered parameters is examined by numerical estimates. The results are presented graphically and the effect of plasma density ramp and decentered parameter on self-focusing of the beams has been discussed.

scholarly journals Relativistic ponderomotive self-focusing of quadruple Gaussian laser beam in cold quantum plasma

2018 ◽  
Vol 36 (3) ◽  
pp. 353-358 ◽  
Author(s):  
Richa ◽  
Munish Aggarwal ◽  
Harish Kumar ◽  
Ranju Mahajan ◽  
Navdeep Singh Arora ◽  
...  
Keyword(s):  
Refractive Index ◽  
Laser Beam ◽  
Electron Temperature ◽  
Density Perturbation ◽  
Beam Width ◽  
Quantum Plasma ◽  
Gaussian Laser Beam ◽  
Self Focusing ◽  
Linear Differential ◽  
Paraxial Ray

AbstractIn the present paper, we have investigated self-focusing of the quadruple Gaussian laser beam in underdense cold quantum plasma. The non-linearity chosen is associated with the relativistic mass effect that arises due to quiver motion of electron and electron density perturbation caused by ponderomotive force. The non-linearity modifies the plasma frequency in the dielectric function and hence the refractive index of the medium. The focusing/defocusing of the quadruple laser depends on the refractive index of the medium. We have set up non-linear differential equation that controls the beam width parameter by using well-known paraxial ray approximation and Wentzel–Krammers–Brillouin approximation. The effect of intensity parameter and electron temperature is observed on laser beam self-focusing in the presence of cold quantum plasma. From the results, it is revealed that electron temperature and the initial intensity of the laser beam control the profile dynamics of the laser beam.

Factors Affecting the Accurate Measurement of Laser Beam Width with CCD Camera

2014 ◽  
Vol 41 (2) ◽  
pp. 0208002 ◽  
Author(s):  
王艳萍 Wang Yanping ◽  
王茜蒨 Wang Qianqian ◽  
马冲 Ma Chong
Keyword(s):  
Laser Beam ◽  
Ccd Camera ◽  
Beam Width ◽  
Factors Affecting

INVESTIGATION OF PECULIARITIES OF LIGHT SCATTERING BY NANOSTRUCTURAL CHANGES IN THE CRYSTAL LATTICE OF FERROELECTRIC BARIUM SODIUM NIOBATE CRYSTAL

2004 ◽  
Vol 03 (06) ◽  
pp. 815-818 ◽  
Author(s):  
S. V. IVANOVA
Keyword(s):  
Light Scattering ◽  
Laser Beam ◽  
Beam Width ◽  
Far Field ◽  
Sodium Niobate ◽  
Incident Laser Beam ◽  
Incident Laser ◽  
Elastic Light Scattering ◽  
Temperature Range ◽  
Thermal Changes

Thermal changes of light scattering images in the far-field were observed under steady illumination by an incident laser beam of finite beam width on barium sodium niobate crystals in the temperature range of 20–500°C. Different patterns of light scattering in far-field were observed — from striped to round-like form with dependence on temperature, conditions of grown, direction of beam and polarization. The round-like form was observed on cooling from 450°C to 240°C. Striped forms of light scattering were observed below 200°C. Correlation of the behavior of elastic light scattering was observed in this temperature range.

scholarly journals Dynamics of Gaussian spikes on Gaussian laser beam in relativistic plasma

2009 ◽  
Vol 27 (4) ◽  
pp. 587-593 ◽  
Author(s):  
A. Singh ◽  
M. Aggarwal ◽  
T.S. Gill
Keyword(s):  
Differential Equations ◽  
Laser Beam ◽  
Nonlinear Differential Equations ◽  
Beam Width ◽  
Main Beam ◽  
Gaussian Laser Beam ◽  
Runge Kutta Method ◽  
Self Focusing ◽  
Gaussian Perturbation ◽  
Paraxial Ray

AbstractIn the present paper, we have investigated the growth of a Gaussian perturbation superimposed on a Gaussian laser beam. The nonlinearity we have considered is of relativistic type. We have setup the nonlinear differential equations for beam width parameter of the main beam, growth and width of the laser spike by using the WKB and paraxial ray approximation. These are coupled ordinary differential equations and therefore these are simultaneously solved numerically using the Runge Kutta method. It has been observed from the analysis that self-focusing/defocusing of the main beam and the spike determine the growth dynamic of the spike.

scholarly journals Combined effect of relativistic and ponderomotive nonlinearity on self-focusing of Gaussian laser beam in a cold quantum plasma

2016 ◽  
Vol 34 (3) ◽  
pp. 426-432 ◽  
Author(s):  
H. Kumar ◽  
M. Aggarwal ◽  
Richa ◽  
T.S. Gill
Keyword(s):  
Laser Beam ◽  
Beam Width ◽  
Combined Effect ◽  
Quantum Plasma ◽  
Gaussian Laser Beam ◽  
Relativistic Case ◽  
Self Focusing ◽  
Ponderomotive Nonlinearity ◽  
Paraxial Ray ◽  
The Impact

AbstractIn the present paper, we have investigated self-focusing of Gaussian laser beam in relativistic ponderomotive (RP) cold quantum plasma. When de Broglie wavelength of charged particles is greater than or equal to the inter particle distance or equivalently the temperature is less than or equal to the Fermi temperature, quantum nature of the plasma constituents cannot be ignored. In this context, we have reported self-focusing on account of nonlinear dielectric contribution of RP plasma by taking into consideration the impact of quantum effects. We have setup the nonlinear differential equation for the beam-width parameter by paraxial ray and Wentzel Kramers Brillouin approximation and solved it numerically by the Runge Kutta Fourth order method. Our results show that additional self-focusing is achieved in case of RP cold quantum plasma than relativistic cold quantum plasma and classical relativistic case. The pinching effect offered by quantum plasma and the combined effect of relativistic and ponderomotive nonlinearity greatly enhances laser propagation up to 20 Rayleigh lengths.

scholarly journals TEM modes influenced electron acceleration by Hermite–Gaussian laser beam in plasma

2016 ◽  
Vol 34 (3) ◽  
pp. 385-393 ◽  
Author(s):  
Harjit Singh Ghotra ◽  
Niti Kant
Keyword(s):  
Laser Beam ◽  
Beam Width ◽  
Electron Acceleration ◽  
Particle Simulation ◽  
Electron Interaction ◽  
Electron Dynamics ◽  
Gaussian Laser Beam ◽  
Trapping Force ◽  
Tem Mode ◽  
Transverse Electromagnetic

AbstractElectron acceleration by a circularly polarized Hermite–Gaussian (HG) laser beam in the plasma has been investigated theoretically for the different transverse electromagnetic (TEM) mode indices (m, n) as (0, 1), (0, 2), (0, 3), and (0, 4). HG laser beam possesses higher trapping force compared with a standard Gaussian beam owing to its propagation characteristics during laser–electron interaction. A single-particle simulation indicates a resonant enhancement in the electron acceleration with HG laser beam. We present the intensity distribution for different TEM modes. We also analyze the dependence of beam width parameter on electron acceleration distance, which effectively influences the electron dynamics. Electron acceleration up to longer distance is observed with the lower modes. However, the higher electron energy gain is observed with higher modes at shorter distance of propagation.

VARIATION OF BEAM DIVERGENCE AS A FUNCTION OF DISCHARGE GAP DISTANCE FOR A NITROGEN LASER

2009 ◽  
Vol 23 (11) ◽  
pp. 1457-1466 ◽  
Author(s):  
H. GOLNABI ◽  
M. R. NOURANI
Keyword(s):  
Laser Beam ◽  
Beam Width ◽  
Propagation Distance ◽  
Beam Divergence ◽  
Divergence Angle ◽  
Nitrogen Laser ◽  
Geometrical Method ◽  
Short Side ◽  
Discharge Gap

A simple geometrical method is used here for divergence determination of a TEA N 2 laser. Using beam cross-section (rectangle) monitoring on the fluorescence paper and geometrical method, the laser beam divergence is determined. Variations of the laser beam width (W) and height (H) with respect to the gap distance are investigated for propagation distances of 10, 30, and 50 cm from the laser aperture. For the 0.52 mm gap, the beam width (W) at a distance of 10 cm is about 2 cm and height is also 2 cm (H = 2 cm ), while both increase to about W = 3.125 cm , and H = 2.4 cm at a distance of 50 cm. At 50 cm distance, for a gap distance range of 0.52 mm, W = 3.125, H = 2.4 cm , which increases to W = 18.5 cm , H = 3.6 cm for gap distances of 1.3 mm. Variations of the defined aspect ratio (H/W) as a function of electrode separation and beam propagation distance are also investigated. Variation of the divergence angle along the short and long side of the rectangular beam is investigated. The divergence angle along the long side for the 0.52 mm gap is about 0.0281 rad, and increases with gap value, and for the 1.3 mm gap is 0.284 rad, corresponding to an average divergence of 0.156 rad in this range. The average divergence in the short side is about 0.01 rad, which is much smaller than the divergence angle along the long side (0.156 rad). This study shows that the discharge gap distance, in addition to its important role in N 2 laser output power, it also plays an important role in the beam divergence, especially in the horizontal plane.

Terahertz generation by the high intense laser beam

2012 ◽  
Vol 78 (5) ◽  
pp. 553-558 ◽  
Author(s):  
MUNTHER B. HASSAN ◽  
A. H. AL-JANABI ◽  
MONIKA SINGH ◽  
R. P. SHARMA
Keyword(s):  
Laser Beam ◽  
Coupling Efficiency ◽  
Beam Width ◽  
Intense Laser ◽  
Thz Radiation ◽  
Electron Mass ◽  
Intense Laser Beam ◽  
Paraxial Ray ◽  
Initial Power ◽  
Frequency Radiation

AbstractThe terahertz (THz) frequency radiation produced as a result of nonlinear interaction of high intense laser beam with low-density ripple in collisionless magnetoplasma has been studied under the paraxial ray approximation. The relativistic change of electron mass leads to self-focusing of laser beam when the initial power of laser beam is greater than its critical power. The self-focused laser beam couples with the pre-existing density ripple to produce a nonlinear current driving the THz radiation at different frequency. The applied magnetic field enhances the nonlinear coupling efficiency. Appropriate expressions for the beam width parameter of the laser beam and the electric vector of the THz wave have been evaluated. Theory and numerical simulations show that this THz source is capable of providing power of Giga watt level.

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