利用二维光谱色散和透镜列阵改善靶面辐照均匀性

利用二维光谱色散平滑技术和透镜列阵(LA)来改善激光驱动器中靶面的辐照均匀性。通过消衍射透镜列阵可得到包络陡峭且中小空间尺度均匀性较好的焦斑。当在光路中加入二维光谱色散平滑单元后,光束在两个互相垂直的方向发生光谱色散,多光束干涉所引起的细密条纹也将在很大程度上被抹平,如果把横向热传导平滑效应也考虑在内,高空间频率的强度波动可进一步被消除。二维理论模拟结果表明采用该方案可获得顶部平坦边缘陡峭的焦斑,而且该方案无需仔细调整靶面的位置,实际应用较方便。

The target irradiation uniformity is improved by using two-dimensional smoothing by spectral dispersion and a lens array (LA). A pattern of steep edges and good middle-scale uniformity is obtained with a diffraction-weakened lens array. When two-dimensional spectral dispersion is employed in the laser chain, the beams experience spectral dispersion in two vertical directions, and the fine stripes caused by beamlets interference are smoothed out greatly. If the effect of lateral thermal conduction smoothing is taken into account, the high spatial-frequency intensity fluctuation can be eliminated further. Two-dimensional theoretic results indicate that a flat-topped and steep-edged target pattern can be achieved in this scheme. Because the position of the target does not require adjustment with high precision, the implement of this scheme is comparatively convenient.