本文關(guān)鍵詞： 強(qiáng)激光大氣傳輸 自聚焦效應(yīng) 球差 光束空間相干性　出處：《四川師范大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：能源和環(huán)保問題是人類今后將面臨的兩大嚴(yán)峻問題。地球之外有豐富的太陽能,利用激光輻射把轉(zhuǎn)換的太陽能輸運(yùn)到地面上是一個(gè)全球性的再生能源新概念。之前的工作僅限于提出了利用自聚焦效應(yīng)可減少對發(fā)射器和接收器尺寸的要求,將強(qiáng)激光束從空間軌道輸運(yùn)到地面。然而,對于強(qiáng)激光大氣傳輸,光束畸變以及光束的部分空間相干性等因數(shù)對光束質(zhì)量的影響是十分顯著的。本論文主要研究了球差和光束空間相干性對激光從太空軌道到地面大氣傳輸自聚焦效應(yīng)的影響,具體研究工作包括:1、球差效應(yīng)對激光從太空軌道到地面大氣傳輸自聚焦效應(yīng)影響的研究。自行編制了激光從太空到地面通過大氣傳輸?shù)哪M仿真程序,用數(shù)值模擬方法研究了球差效應(yīng)對強(qiáng)激光大氣傳輸能量輸運(yùn)的影響。研究發(fā)現(xiàn):地面上壓縮光斑半徑不僅與太空軌道發(fā)射器尺寸有關(guān),還與激光的球差大小有關(guān)。地面上壓縮光斑半徑隨太空軌道發(fā)射器尺寸的增大而減小,但球差效應(yīng)對地面上壓縮光斑半徑的影響還與太空軌道發(fā)射器尺寸有關(guān)。對于大尺寸太空軌道發(fā)射器,無球差高斯激光比球差高斯激光壓縮更厲害,此時(shí)應(yīng)該避免球差。然而,對于小尺寸太空軌道發(fā)射器,負(fù)球差使得激光光斑壓縮效果更好,光斑能夠比衍射極限更小,因此實(shí)際中可利用負(fù)球差達(dá)到更好壓縮光斑的目的。值得指出的是,激光成絲崩塌的閾值臨界功率與壓縮光斑大小成反比。因此,實(shí)際中必須同時(shí)考慮這兩個(gè)因素,即最佳激光發(fā)射功率必然涉及地面上光斑大小與閾值臨界功率之間的權(quán)衡。所得研究結(jié)果對強(qiáng)激光大氣傳輸能量輸運(yùn)具有重要意義。2、光束空間相干性對激光從太空軌道到地面大氣傳輸自聚焦效應(yīng)影響的研究。自行編制了部分空間相干光從太空到地面通過大氣傳輸?shù)哪M仿真程序,用數(shù)值模擬方法研究了光束空間相干性對強(qiáng)激光大氣傳輸能量輸運(yùn)的影響。研究發(fā)現(xiàn):相干性越差的激光其自聚焦效應(yīng)越弱(即部分空間相干光較完全空間相干光不會減小太空軌道發(fā)射器尺寸和地面接收器尺寸),即便如此,部分空間相干光達(dá)到地面上的光斑尺寸仍然可以小于衍射極限。特別地,相干性越差的激光能夠承受的成絲崩塌的閾值臨界功率越大,即有利于把更高強(qiáng)度的激光輸運(yùn)到地面。3、光束空間相干性與激光最大發(fā)射功率和太空軌道發(fā)射器尺寸關(guān)系的研究。推導(dǎo)出了獲得最大光束壓縮并保證光束質(zhì)量(無成絲和崩塌)時(shí)激光的發(fā)射功率、空間軌道發(fā)射器尺寸與光束空間相關(guān)長度應(yīng)滿足的關(guān)系式,并用數(shù)值計(jì)算證明了該解析關(guān)系式的正確性。該理論結(jié)果對實(shí)際強(qiáng)激光大氣傳輸能量輸運(yùn)應(yīng)用具有重要的指導(dǎo)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.
【學(xué)位授予單位】：四川師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN241

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