Thermal Deformations Influence Of Reflector On Propagation Properties Of Laser Beams Through Turbulent Atmosphere

With the development of laser technology, in laser systems, such as laser measure, laser radar, photoelectric counterwork, photoelectric exploration and so on, an atmospheric target is needed to be captured, tracked, measured and explored exactly in order to make the beam steady. In ideal condition, the phase of the beam is no aberration, intensity is invariable and the required information is incepted exactly. In actually, laser transmitting in the air is affected by the linear and non-linear optic effects, such as refraction, absorption, turbulence, thermal blooming and atmospheric breakdown. In the recent several years, there have been substantial interests studying the propagation of partially coherent light in the free space and turbulent atmosphere, On the other hand, because of the impact of the laser on the atmosphere is significant, using the laws mentioned above, the laser beams or other light source can be a useful tool for atmospheric detection. Therefore, it is important to study and analyze laser propagation in atmosphere in laser equipment application and the result can be used designing of the laser system.Based on the laser fields from a positive confocal unstable resonator (ab initio), and considered the internal resonator mirror thermal distortion effects on the beam, the propagation characteristics of the beam through turbulent atmosphere are investigated by means of fast Fourier transform algorithm (FFT). The intensity distributions of the output laser far-field are obtained to analyze the propagation characteristics of laser beam through the turbulent atmosphere as functions of different propagation distances. The results show that the peak intensity of the laser pattern becomes depressed, the spread of the far field diagram patterns is broaden, with increasing of the transmission distance and the thermal distortion of the laser resonator.βparameter and strehl ratio are introduced to estimate the beam quality characteristics. It is found that the quality of the beam through strong turbulence is affected much less obvious than the beam through weak turbulence against thermal distortion. In the same atmospheric conditions, a certain distance, the greater the mirror thermal distortion, the worse the beam quality characteristics.