Laser beam surveying, refractive index measurements and the making of a 360 degree reflection hologram

1993 ◽  
Author(s):  
David Foster
Keyword(s):  
Refractive Index ◽  
Laser Beam ◽  
Reflection Hologram

Relativistic self-focusing of a rippled laser beam in a plasma

1999 ◽  
Vol 62 (4) ◽  
pp. 389-396 ◽  
Author(s):  
M. V. ASTHANA ◽  
A. GIULIETTI ◽  
DINESH VARSHNEY ◽  
M. S. SODHA
Keyword(s):  
Refractive Index ◽  
Laser Beam ◽  
The Self ◽  
Laser Beams ◽  
Radial Dependence ◽  
Main Beam ◽  
Gaussian Laser Beam ◽  
Self Focusing ◽  
Saturation Effects ◽  
Paraxial Ray

This paper presents an analysis of the relativistic self-focusing of a rippled Gaussian laser beam in a plasma. Considering the nonlinearity as arising owing to relativistic variation of mass, and following the WKB and paraxial-ray approximations, the phenomenon of self-focusing of rippled laser beams is studied for arbitrary magnitude of nonlinearity. Pandey et al. [Phys. Fluids82, 1221 (1990)] have shown that a small ripple on the axis of the main beam grows very rapidly with distance of propagation as compared with the self-focusing of the main beam. Based on this analogy, we have analysed relativistic self-focusing of rippled beams in plasmas. The relativistic intensities with saturation effects of nonlinearity allow the nonlinear refractive index in the paraxial regime to have a slower radial dependence, and thus the ripple extracts relatively less energy from its neighbourhood.

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.

Estimates of the Refractive Index and Regular Refraction of Optical Waves in the Atmospheric Boundary Layer: Part 2, Laser Beam Refraction

2018 ◽  
Vol 31 (5) ◽  
pp. 445-450 ◽  
Author(s):  
S. L. Odintsov ◽  
V. A. Gladkikh ◽  
A. P. Kamardin ◽  
V. P. Mamyshev ◽  
I. V. Nevzorova
Keyword(s):  
Boundary Layer ◽  
Refractive Index ◽  
Laser Beam ◽  
Atmospheric Boundary Layer ◽  
Optical Waves

Fluidic Laser Beam Shaper by Using Thermal Lens Effect

2011 ◽  
Author(s):  
Hong Duc Doan ◽  
Yoshihiko Akamine ◽  
Kazuyoshi Fushinobu
Keyword(s):  
Refractive Index ◽  
Pump Power ◽  
Absorption Coefficient ◽  
Laser Beam ◽  
Probe Beam ◽  
Thermal Lens ◽  
Refractive Index Distribution ◽  
Index Distribution ◽  
Thermal Lens Effect ◽  
Flat Top Beam

Laser measurement and laser processing techniques have been gaining strong attention from various applications [1,2]. This research aims at the development of a fluidic laser beam shaper, and in order to fulfill the objective, characteristics of the thermal lens effect are studied. This phenomenon has the optical property of a concave lens since the refractive index distribution on the optical axis is formed when the liquid is irradiated. One reason for the refractive index distribution in the liquid is the temperature distribution in the liquid when it is irradiated. In this research, effects of the pump power and propagation distance of the probe beam to probe beam profile are investigated experimentally and theoretically, in order to develop fluidic laser beam shaper. It is indicated that, by controlling some parameters in thermal lens system as pump power (in the regime of linear optics) and absorption coefficient, input Gaussian beam can be converted into flat-top beam profile. The relationship among the distance to obtain a flat-top beam, pump power and absorption coefficient is investigated to show the flexibility of fluidic laser beam shaper in many fields of laser application.

scholarly journals Drift Reduction of a 4-DOF Measurement System Caused by Unstable Air Refractive Index

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6329
Author(s):  
Ruijun Li ◽  
Yongjun Wang ◽  
Pan Tao ◽  
Rongjun Cheng ◽  
Zhenying Cheng ◽  
...  
Keyword(s):  
Refractive Index ◽  
Laser Beam ◽  
Measurement System ◽  
Degrees Of Freedom ◽  
Cost Effective ◽  
Control Mode ◽  
Detection Accuracy ◽  
Long Distance ◽  
Cost Effective Method ◽  
Novel Method

Laser beam drift greatly influences the accuracy of a four degrees of freedom (4-DOF) measurement system during the detection of machine tool errors, especially for long-distance measurement. A novel method was proposed using bellows to serve as a laser beam shield and air pumps to stabilize the refractive index of air. The inner diameter of the bellows and the control mode of the pumps were optimized through theoretical analysis and simulation. An experimental setup was established to verify the feasibility of the method under the temperature interference condition. The results indicated that the position stability of the laser beam spot can be improved by more than 79% under the action of pumping and inflating. The proposed scheme provides a cost-effective method to reduce the laser beam drift, which can be applied to improve the detection accuracy of a 4-DOF measurement system.

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