球差和光束空间相干性对激光从太空轨道到地面大气传输自聚焦效应的影响

发布时间：2018-02-24 23:21

本文关键词： 强激光大气传输自聚焦效应球差光束空间相干性　出处：《四川师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：能源和环保问题是人类今后将面临的两大严峻问题。地球之外有丰富的太阳能,利用激光辐射把转换的太阳能输运到地面上是一个全球性的再生能源新概念。之前的工作仅限于提出了利用自聚焦效应可减少对发射器和接收器尺寸的要求,将强激光束从空间轨道输运到地面。然而,对于强激光大气传输,光束畸变以及光束的部分空间相干性等因数对光束质量的影响是十分显著的。本论文主要研究了球差和光束空间相干性对激光从太空轨道到地面大气传输自聚焦效应的影响,具体研究工作包括:1、球差效应对激光从太空轨道到地面大气传输自聚焦效应影响的研究。自行编制了激光从太空到地面通过大气传输的模拟仿真程序,用数值模拟方法研究了球差效应对强激光大气传输能量输运的影响。研究发现:地面上压缩光斑半径不仅与太空轨道发射器尺寸有关,还与激光的球差大小有关。地面上压缩光斑半径随太空轨道发射器尺寸的增大而减小,但球差效应对地面上压缩光斑半径的影响还与太空轨道发射器尺寸有关。对于大尺寸太空轨道发射器,无球差高斯激光比球差高斯激光压缩更厉害,此时应该避免球差。然而,对于小尺寸太空轨道发射器,负球差使得激光光斑压缩效果更好,光斑能够比衍射极限更小,因此实际中可利用负球差达到更好压缩光斑的目的。值得指出的是,激光成丝崩塌的阈值临界功率与压缩光斑大小成反比。因此,实际中必须同时考虑这两个因素,即最佳激光发射功率必然涉及地面上光斑大小与阈值临界功率之间的权衡。所得研究结果对强激光大气传输能量输运具有重要意义。2、光束空间相干性对激光从太空轨道到地面大气传输自聚焦效应影响的研究。自行编制了部分空间相干光从太空到地面通过大气传输的模拟仿真程序,用数值模拟方法研究了光束空间相干性对强激光大气传输能量输运的影响。研究发现:相干性越差的激光其自聚焦效应越弱(即部分空间相干光较完全空间相干光不会减小太空轨道发射器尺寸和地面接收器尺寸),即便如此,部分空间相干光达到地面上的光斑尺寸仍然可以小于衍射极限。特别地,相干性越差的激光能够承受的成丝崩塌的阈值临界功率越大,即有利于把更高强度的激光输运到地面。3、光束空间相干性与激光最大发射功率和太空轨道发射器尺寸关系的研究。推导出了获得最大光束压缩并保证光束质量(无成丝和崩塌)时激光的发射功率、空间轨道发射器尺寸与光束空间相关长度应满足的关系式,并用数值计算证明了该解析关系式的正确性。该理论结果对实际强激光大气传输能量输运应用具有重要的指导作用。
[Abstract]:Energy and environmental protection are two major problems facing mankind in the future. There is abundant solar energy outside the earth. The use of laser radiation to transport converted solar energy to the ground is a new global concept of renewable energy. Previous work was limited to the idea that the use of self-focusing could reduce the size of transmitters and receivers, Transport a strong laser beam from space orbit to the ground. However, for intense laser atmospheric transmission, The influence of beam distortion and partial spatial coherence on beam quality is very significant. In this paper, the effect of spherical aberration and beam spatial coherence on the self-focusing effect of laser propagation from orbit to atmosphere is studied. The specific research work includes: 1, the influence of spherical aberration effect on the self-focusing effect of laser transmission from space orbit to ground atmosphere. A simulation program of laser transmission from space to ground through atmosphere has been compiled by ourselves. The effect of spherical aberration on the energy transport of intense laser in atmosphere is studied by numerical simulation. It is found that the radius of compressed spot on the ground is not only related to the size of space orbit launcher. It also depends on the spherical aberration of the laser. The radius of the compressed spot on the ground decreases with the size of the orbital launcher. However, the effect of spherical aberration on the radius of compressed spot on the ground is also related to the size of space orbit launcher. For large size space orbit launchers, Gao Si laser without spherical aberration is more compressed than Gao Si laser without spherical aberration, so the spherical aberration should be avoided at this time. For small space orbit launchers, the negative spherical aberration makes the laser spot compression better and the spot can be smaller than the diffraction limit, so the negative spherical aberration can be used to achieve the purpose of better compression of the spot in practice. It is worth noting that, The threshold critical power of the laser filament collapse is inversely proportional to the size of the compressed spot. Therefore, in practice, these two factors must be considered simultaneously. That is, the optimal laser emission power must involve the tradeoff between the spot size and the threshold critical power on the ground. The results obtained are of great significance for the transport of energy from the atmosphere to the intense laser, and the spatial coherence of the beam is of great significance to the laser from the terabyte. Study on the effect of autofocus effect on Atmospheric Transmission from Space-Orbital to ground. A simulation program for the propagation of partially spatially coherent light from space to the ground through the atmosphere has been compiled by ourselves. The effect of beam spatial coherence on the energy transport of intense laser propagation in atmosphere is studied by numerical simulation. It is found that the less coherent the laser is, the weaker the self-focusing effect is (that is, the partially spatially coherent light is more fully spatially coherent than the complete spatial coherence). Light will not reduce the size of the orbital launcher and the size of the ground receiver, even so, The speckle size of partially spatially coherent light on the ground can still be smaller than the diffraction limit. In particular, the lower the coherence, the greater the threshold critical power of filamentous collapse. The relationship between beam spatial coherence and laser maximum emission power and space orbit launcher size is studied. The maximum beam compression is obtained and the beam quality is guaranteed. The emission power of a laser without wire formation and collapse, The relationship between the size of space orbital launcher and the spatial correlation length of beam is satisfied, and the correctness of the analytical formula is proved by numerical calculation. The theoretical results are important for guiding the application of energy transport in atmospheric transmission of intense laser.
【学位授予单位】：四川师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN241

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