Computer Aided Simulation to Study the Effect of Atmospheric Turbulence on Ideal Gaussian Laser Beam Using Matlab and Lab-View

Gaussian Beam is a beam of electro-magnetic radiation whose traverse (Electric field & Intensity) disturbance are well approximated by Gaussian Function. In this paper, we simulated the effect of the atmospheric turbulence on the propagation of an ideal Gaussian Beam. To do this we created a Kolmogorov phase screen and integrated with an Ideal Gaussian Beam Using MATLAB and Lab-VIEW Integration. This will help in great deal to understand the propagation of laser beams in turbulent atmosphere with graphical appearance i.e., Beam Profiling. . Lab-VIEW (Laboratory Virtual Instrumentation Engineering Workbench) is a graphical programming language where flow of data determines the execution. A number of applications have been built using the Lab-VIEW like: Robotics, Instrumentation and Control, Signal processing etc. For the integration of MATLAB Program in Lab-VIEW We used LabVIEW Mathscript RT Module. Introduction:While propagating through the atmosphere, Laser spreads laterally due to diffraction. Because of the unique properties of Laser Beams, such as high brightness, a laser beam is relatively sensitive with respect to the microstructure of the atmospheric Turbulence. It is often observed, however, that laser beams have a tendency to wander randomly about their propagation direction (rectilinear path) while propagating through the atmosphere, and appear to accumulate fluctuations in their light intensity, called scintillation (see Fig 1 and 2) While atmospheric turbulence is a stochastic process, there is ‘structure’ in randomness. Kolmogorov considered the simplified problem of a non-viscous and isotropic atmosphere, i.e., that the outer scale is infinity and the inner scale is zero. These assumptions indicates well-defined distribution for the randomness in the refractive index of the atmosphere, that can be applied in the laboratory Experiment. One of the key findings of Kolmogorov has been that the turbulence strength can be described by a single parameter, the atmospheric structure constant, Cn2 . Large Cn2 indicates strong turbulence , and vice versa. Matlab® stands for Matrix LABoratory and the software is built up around vectors and matrices. It is widely used in all areas of education, applied mathematics and research at universities, R&D Departments and in the industry. The software particularly useful for linear algebra but MATLAB is also a great tool for solving algebraic and differential equations and for numerical integration. MATLAB has excellent graphic tools and can produce nice 2D and 3D pictures. MATLAB is also useful for signal & image processing, and optimization, etc . In MATLAB we coded for generating a Kolmogorov phase screen and generating an Ideal Gaussian Beam. Lab-VIEW stands for Laboratory Virtual Instrumentation Engineering Workbench. It is a platform and development environment for a visual programming language from National Instruments. The graphical language is named as ‘G’. It has a broad field of application in education and research to work in real time environment. It has two panels namely Front Panel (where the real time observations are taken) and the Block Diagram (where the graphical programming is done). In Lab-VIEW we designed a Virtual Instrument to observe the Kolmogorov turbulence in ideal Gaussian Beam that generates a 3D surface view of ideal Gaussian Beam, Kolmogorov phase screen and the turbulence affected Beam. We used Lab-VIEW MATHSCRIPT RT Module to integrate Matlab Programming with the Lab-VIEW graphical program. Lab-VIEW MATHSCRIPT RT can deploy .m file scripts as a part of Lab-VIEW application and combining graphical & textual programming. This can be done using Mathscript Node.