The Effects Of Turbulence On Laser Transmission Quality And Improvement

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, it will produce beam jitter, intensity fluctuations, drift, beam expansion and a series of atmospheric turbulence effects when the beam through the refractive index of the different vortex element. To overcome the effects of atmospheric turbulence for the problems, there are many ways to choose from. Census drawn up, these methods can be divided into two basic types: (1) phase compensation. Choose to launch the initial wave-front laser beam to remove part of the phase distortion; (2) intensity rehabilitation. Modified the light intensity distribution of laser beam emitted ,obtain the phase change that can be trimmed in the beam propagation path,in order to increase the laser intensity that can reach the focal plane. Adaptive optical method and the multi-beam launch are designed based on these two types.Multi-beam emission means launch unrelated multi-beam laser from some mirrors that the transmitter aperture is greater than the distance between the emission of atmospheric coherence length, non-coherent superposition of the receiver in the far field ,to overcome the atmospheric laser transmission turbulence effects, to achieve effective compensation of atmospheric channel. Multi-beam emission is essentially a non-coherent superposition of technology, which can effectively reduce the receiving end of the light intensity fluctuation effects. In this paper, the calculation and the discution of far-field beam quality parameter verify the superiority of multi-beam emission . Adaptive optics method, the core is the real-time induction phase distortion arising to the introduction of phase shift control circuit, making the signal to launch the wave laser beacon of light before and conjugate wave front, to compensate the effect of the beam phase fluctuations .The purpose is to target the maximum power density.Text is divided into there chapters, the main research says:1. Describe the main factors of light intensity fluctuation that caused in the process of laser propagation in the atmosphere . 2. Describe beam propagation rules in turbulent atmosphere by statistical theory ;3. Describe the principle of multi-beam emission technology and verify the multi-beam methord has advantages in reduced light intensity fluctuations by calculating the far-field beam quality parameter .4. Described the principle of adaptive optics method and analysis of its limitations.