利用部分相干光和同心角偏差透镜列阵实现二维靶面均匀辐照

摘要

A method of employing a lens array（LA） and partially coherent light（PCL） is presented for uniform irradiation on targets in inertial confinement fusion.Quasi-near field spots with a profile of sharp edge and flat top can be obtained with an LA,while the spatial coherence of the incidence beam is reduced by PCL.An appropriate concentricity deviation（CD） of LA results in the superposition of beamlets at the focus dislocated by a small amount each other and the CD and PCL reduce the fringe separations,thus the interference fringes become denser and the small-scale intensity non-uniformity of intensity distribution is suppressed.Based on the generalized diffraction integral theory,the intensity distribution of a Gaussian Schell Beam（GSB）,point focused by an LA and a spherical lens is investigated in detail by two-dimensional simulation.And irradiation uniformity effects are compared with coherent light and partially coherent light after the LA.Numerical results indicate that using an appropriate CD and moving the target slightly from the exact focal plane of the principal focusing,a well-irradiated laser spot and great energy efficiency can be obtained.%提出利用部分相干光通过透镜列阵系统实现靶而的均匀辐照,透镜列阵能获得边缘陡峭且顶部较平坦的准近场焦斑,透镜列阵的适当同心度偏差又使各子束的斑纹相互稍微错开,使干涉斑纹变密,而入射的激光是空间相干性减少了的部分相干光,可进一步抑制了透镜列阵系统焦斑的小尺度不均匀性.使用广义衍射积分理论,对高斯-谢尔光束通过透镜列阵光学系统的焦斑光强分布进行了详细的二维模拟研究,比较了完全相干光与部分相干光经过透镜列阵的匀滑效果.数值模拟表明,应用同心度偏差和适当离焦时,可实现焦斑均匀性和能量利用率同时达到最佳的效果.