The Influence Of Atmospheric Turbulence And Thermal Blooming On The Laser Beam Quality In The Far Field

When the high-power laser through the atmosphere, linearity and the non-linear effect have the influence to the laser propagation and the beam quality in the far field.In the field of atmospheric optics, atmospheric turbulence is the local temperature and pressure changes arising after the random changes in the refractive index. Many turbulent temperature, density and refractive index with a small difference between different vortex element, the vortex element, such as wind speed and constant movement of the rapid emergence and disappearance, when the beam through the vortex of different refractive index will have a beam element of jitter, intensity fluctuations, drift, such as beam expansion and a series of atmospheric turbulence effects.Thermal blooming is a very important nonlinear effect. When the high-power laser propagation in the atmosphere, the molecular and atmospheric aerosol particles will absorb laser energy with heating expansion and density decreased, resulting in decreased local refractive index, which is equivalent to a normally formed in the atmosphere from the negative thermal lens, beam caused by expansion of bending distortion is refracted beam change in a very complex shape. It is the existence of such phenomena, to a certain extent, that hampered the high-power laser propagation.The influence of atmospheric turbulence and thermal effect on the laser beam quality in the far field in this thesis. Propagation of laser beam through atmospheric turbulence and thermal effect are treated with phase screen approximation. The main results achieved in this thesis can be summarized as follows:1. Beam quality parameters in the far field versus time for the influence of atmospheric turbulence and thermal effect.2. Without the consideration of turbulence, this thesis studies the influence of thermal effect on the beam quality in the far field and analyzes the beam quality parameters variation with the change of time by two methods.3. With the consideration of thermal effect, it studies the influence of turbulence on the laser beam quality in the far field and analyzes the laser beam quality parameters variation with the change of time by two methods.