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采用大型透镜阵列对激光波前进行采样,实现了对宽光束的测量。大口径激光束经过大型透镜阵列进行采样形成光斑点阵,通过成像系统,获取点阵图像,得到激光束波前信息,根据激光传输理论和光学系统像差理论,已知激光束的波前函数和强度分布时,可以求出激光束会聚后在焦面处任意位置的光强,因此激光束的波前、发散角、近场分布、远场分布等参数能够通过测量求解得到。 相似文献
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分析了楔形镜和中性玻璃衰减片组对光束的衰减原理,采用反射式楔形镜作为无像差定量衰减器,并同时使用中性玻璃衰减片组微调光束能量。实验测量了LD泵浦激光模式发生器基模和高阶模条件下激光束的M2因子,结果表明:楔形镜反射式衰减器对光束质量无显著影响,将楔形镜第一次表面反射作为无像差定量衰减,入射角在0~55°范围内,单棱镜表面反射光束能量为入射光能量的4.3%,通过多块组合可以得到更大的衰减;可采用中性玻璃衰减片组对激光光束的衰减进行精细控制,使其满足CCD探测器动态范围要求。该结论可为高精度激光参数测量装置光衰减系统的研制提供理论依据。 相似文献
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用Hartmann-Shack(H-S)波前传感器可以准确测量穿过超声速流场的激光波面及其变化过程,进一步计算可以获得光束质心漂移、远场分布等数据。给出了H-S方法测量穿过超声速流场激光波面的原理,采用模式法进行了波前重构,计算了在几种流场条件下的激光波面像差特性PV值,RMS值和Zernike像差系数、Strehl比和环围能量曲线等。结果表明,H-S法可以很好地反映流场建立、稳定和结束过程中Zernike像差的变化。比较无流场和给定参数的超声速流场,激光穿越后产生的最明显的像差变化为离焦和低阶像散的增大。在相同流场参数下,无模型时光束质量好于有模型时光束质量。 相似文献
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高功率激光光束特性对激光加工的影响 总被引:4,自引:0,他引:4
决定光与物质相互作用的激光束的波长、入射角、偏振特性以及时间和空间特性是激光材料加工的主要光束特性。激光束的光束质量是其空间特性的量化反映。通过对两种不同激光加工系统输出激光光束质量进行测量和计算,根据多模激光束的聚焦理论,以及对激光深熔焊接实验结果的分析,研究了光束质量对深熔焊接焊缝成形的影响。结果表明,光束质量对聚焦光束的焦斑、聚焦角和焦深的影响不仅体现了激光源的可聚焦性,而且也标志了激光源的可加工能力,这是聚焦系统和焦点位置在选择过程中应该考虑的重要因素。 相似文献
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以广义惠更斯-菲涅尔衍射理论为基础,采用Zernike多项式描述像差光束畸变波前相位,研究超高斯光束因卡式系统加工和装调导致波像差劣化后,通过传输在远场聚焦性能。分析主次镜系统波像差下降到1/13λ左右时,对应像散和慧差对聚焦位置处光强分布和光斑桶中功率PIB影响。结果表明:相对理想系统,像差会导致聚焦位置处光束展宽,80%处桶中功率PIB下降明显,但对应95%能量范围光斑直径在设计值允许范围内,仍然满足总体使用要求。 相似文献
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基于衍射理论和神光II升级激光装置的光路结构及光学元件波前像差,建立了激光装置光束波前像差传输计算模型,用以获取在实验中难以取得,但对激光系统设计和安全运行非常重要的变形镜校正面型、放大器动态波前像差、空间滤波器波前像差和焦斑形态等过程数据。利用该模型对激光装置常规运行时的静态传输、变形镜加压静态传输和大能量发射3种状态下的波前传输进行理论分析,计算结果与实验测量相一致,并在此基础上对变形镜未加压大能量发射波前传输进行计算。计算模型可用于指导相关器件的设计,优化激光运行控制模式,有利于提高激光装置输出波前质量。 相似文献
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为了了解光束在尾流气泡中的传输特性,为前向光尾流的探测提供理论依据,研究了光束在尾流中传输时传播方向上和横截面方向上的辐射强度分布特性.基于辐射传输方程的小角度近似解,得到了探测截面上的约化强度和漫射强度的表达式,其中漫射强度表征了复散射的强弱;针对典型的尾流气泡分布,通过数值计算分析了光束传输方向上的约化强度和漫射强度与接收视场角、光学厚度和光束大小的关系,也计算分析了光束横截面方向上的辐射强度随光束大小和横向距离的变化关系.结果表明,光束在尾流气泡中传输时复散射效应明显,且复散射的强弱与接收视场角、光束直径、光学厚度和横向距离密切相关. 相似文献
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It is shown that the possibility of changing a laser light beam intensity distribution exists when the output mirror transmittance depends on the transverse plane coordinates. Methods of manufacture of inhomogeneously transmitting laser mirrors with constant phase of the reflected beam over the whole surface are described. Two examples of application of such systems are considered: one for obtaining a laser beam with constant intensity distribution in the transverse plane, the other for single-segment energy extraction from high-order transverse modes. The total laser output power is shown to be almost the same as for use of a homogeneous output mirror. 相似文献
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利用Richards-Wolf矢量衍射积分公式,获得线偏振贝塞耳-高斯光束经具有初级慧差的高数值孔径系统聚焦后的三维光场复振幅函数,根据复振幅函数模拟了不同慧差系数下线偏振贝塞耳-高斯光束各分量及总光场在焦平面上的光强分布模式。研究结果表明,初级慧差使线偏振贝塞耳-高斯光束聚焦光场在焦平面的分布由双轴对称变成单轴对称,光强模式发生改变;各分量及总光场的光强模式中的光斑位置随初级慧差系数的增大偏离光轴;大的初级慧差使焦平面出现干涉条纹。 相似文献
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We describe an adaptive aberration correction technique based on an ant colony algorithm for solid-state lasers and a general class of other adaptive optics systems. We show that it is possible to compensate phase aberrations without wavefront sensing in this approach, which iteratively adjusts the control voltages of a deformable mirror to maximize certain system performance metrics of the far-field intensity distribution of the laser beam. The effectiveness of this approach is analyzed numerically by use of a 37-element piezoelectric deformable mirror and a variation of the Strehl ratio as the metric. Results demonstrate that this approach can effectively compensate the phase distortions of laser beams and significantly improve beam quality. A comparison indicates that this approach is much faster than a genetic algorithm while achieving almost the same beam quality. 相似文献
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Guiyan Zhao 《Optik》2011,122(1):29-32
The effect of tilt and astigmatism aberration of the turbulent atmosphere on the intensity distribution of a focused vortex carrying Gaussian beam was investigated based on the extended Fresnel-Kirchhoff diffraction integral and the quadratic approximation of phase structure function. Our results have shown that the intensity distribution on the focal plane in the effect of tilt aberration changes with the turbulent strength, the propagation distance and the topological charge of the initial beam. The propagation distance is larger, the focal spot size will be larger, and the central dip will be less deep. It is also noticed that the intensity distribution of a beam with single topological charge is affected more by tilt aberration in comparison to the beam with double topological charge. The effect of astigmatism on the intensity distribution is quite less than that of tilt aberration. For focused beam propagation in atmosphere, the effect of the tilt aberration on the intensity distribution of optical vortex beam is the main effect of total turbulent aberration. 相似文献
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The normalized intensity distributions at the focal plane of a vortex carrying Gaussian beam propagating in weak/middle turbulent atmosphere channel with z-tilt aberration, defocus aberration, astigmatism aberration or total turbulent aberration are discussed by numerical calculation. Our results show that the effect of z-tilt aberration on the intensity distribution of optical vortex beam is main effect of total turbulent aberration. In weak turbulent region, the effects of defocus and astigmatism aberration on the intensity distribution of a vortex carrying Gaussian beam can be ignored. In middle turbulent region, the effect of z-tilt aberration is still the most significant, but the effects of defocus and astigmatism aberrations, specially the effect of astigmatism on the center dark core of the intensity distribution at focal plane, can no longer be disregarded. Our results also show that for three low order aberrations, the beam with values of the topological charge, the beam have larger beam-radius and undergo smaller effects of z-tilt turbulent aberration on the doughnut distribution. For defocus aberration, the radius of the center dull of beam intensity increases with the values of topological charges increasing. And for astigmatism aberration, the beam with odd number topological charges, the center dull speck of beam intensity becomes to the bright speck. But for even number topological charges, the center dull speck of beam intensity maintains the dull one. 相似文献
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The beam quality of the laser beams after spectral beam combining (SBC) has been analyzed in this paper. Based on the propagation model of the spectral beam combining system, the expression for the output field of an individual beam passing through the spectral beam combining system with lens aberration has been given and the intensity distribution of the combined beam has been studied by the principle of incoherent superposition. Consequently, according to the intensity second-order moments method, the M2-factor of the combined beam has been calculated and the effect of lens aberration on the characteristics of the combined beam has been analyzed quantitatively. It can be shown that the SBC system can improve the beam quality of laser array significantly, and the M2-factor of the combined beam passing through the ideal spectral beam combining system is almost the same as that of an individual beam. For the spectral beam combining system with lens aberration, the spherical aberration has greater effect on the off-axis beam than on the on-axis beam, and the beam quality of combined beam degrades with increase in lens aberration. 相似文献
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In this paper, taking the partially coherent flat-topped (PCFT) beam as an example, we investigate the intensity distribution of broadband beams with astigmatic aberration propagating through a turbulent atmosphere. The analytic expressions for the intensity of the beams propagating through the turbulent atmosphere are derived. It is shown that the intensity distribution of the broadband aberrated PCFT beams in the turbulent atmosphere are closely related with the astigmatism aberration, the strength of atmospheric turbulence, the order of flatness, the correlation of source and the bandwidth of PCFT beams. It is important to note that the position of the focal plane of the broadband aberrated (or not) PCFT beams can be modulated by changing the aberration, the order of flatness, the correlation and the bandwidth of PCFT beams. 相似文献
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A.B. Schvartsburg 《Optics Communications》1974,10(2):127-132
In this paper the aberrations of a centered axially symmetric electromagnetic wave beam in a nonlinear medium are examined. A formula is obtained, which describes the intensity distribution of the beam near the aberration point. The procedure for investigating high-order aberrations is demonstrated. The influence of the initial distribution of the intensity and the phase on the picture of the aberration is examined. 相似文献