【摘要】 基于非稳光场的相干光理论,研究了部分空间和部分时间相干高斯-谢尔模型脉冲光束在大气湍流中的光谱变化规律。给出了两者在大气湍流中的光谱传输公式。数值计算结果表明,由于光阑衍射效应的影响,光谱沿轴向、径向均出现蓝移或红移,随着相对传输距离z/z0、空间相干参数β和折射率结构常数C2n的增大,脉冲时间相干长度Tc的减小,轴向光谱蓝移量(或红移量)逐渐增大,由明显的起伏逐渐趋于稳定并且沿径向出现了光谱开关。其数目随着截断参数δ的增大,光阑的衍射效应减弱而逐渐增多,光谱跃迁量△逐渐减小;随着脉冲时间相干长度的增大,光谱跃迁量逐渐减小,开关位置逐渐靠近z轴;而随着折射率结构常数的增大,光谱跃迁量逐渐减小,开关位置逐渐远离z轴。随着相对传输距离的增大,大气湍流对光谱的影响逐渐增大而光阑衍射效应逐渐减小,因此,光阑衍射在近场区对光谱影响较大,而大气湍流在远场区对光谱影响较大。更多还原

【Abstract】 Based on the coherent theory of non-stationary light wave fields,the characteristic of spectral change of diffracted spatially and temporally partially coherent Gaussian-Schell model pulsed beams through atmospheric turbulence was studied and the analytical expression was derived.Analytical results show that as a result of the influence of diffractive aperture,both on-axis spectrum and radial spectrum appear blue-shifted(or red-shifted).Blue-shifted value(or red-shifted value) of on-axis spectrum increases gradually with the increase of the relative distance z/z0,spatial coherence parameter β andrefractive index constant,and the decrease of the temporal coherence length Tc,and goes to stabilization from clearly undulation and shows spectral switches on radical direction at last.The numbers of spectral switches increase and the spectral transition height △ decrease with the increase of truncation parameter δ and diffractive effect.The positions of spectral switches gradually approach to z axes as temporal coherence length Tc increases and the spectral transition height △ decrease.The positions of spectral switches is gradually far from z axes as refractive index constant Cn2 increases.With the increase of the relative distance z/z0,influence of atmospheric turbulence on spectrum increases and the effect of diffractive aperture decreases.Therefore,influence of diffractive aperture on spectrum is larger in the near field than that in the far field while the influence of atmospheric turbulence on spectrum is larger in the far field than that in the near field.更多还原