Optical zooming based on focusing grating in direct drive ICF.
Optical zooming based on focusing grating in direct drive ICF.
复制标题
直驱ICF中基于聚焦光栅的光学变焦。
作者：
Xiaoxia Huang;D. Hu;Wei Zhou;W. Dai;X. Deng;Q. Yuan;Qihua Zhu;F. Jing
在直接驱动 ICF 中，光学变焦是通过在目标压缩时减小激光束的光斑尺寸来减轻交叉光束能量转移并提高流体动力效率的有效方法。本文提出了一种新颖的光学变焦方案，该方案采用聚焦光栅来聚焦宽带激光脉冲，从而改变单束内目标上的光斑尺寸。实验上，在准直光后放置40mm×40mm洁净孔径的聚焦光栅，成功实现了在1052.43nm~1053.23nm波长范围内散焦波前分布的峰谷为0.73μm。扩展到360mm×360mm激光束的全尺寸聚焦光栅，得出3次谐波光范围从350.81 nm到351.08 nm，焦点光斑减少达到21.8%，使用300 µm整形连续相位板从375 µm减少到294 µm。
In direct drive ICF, optical zooming is an effective way to mitigate cross-beam energy transfer and increase the hydrodynamic efficiency, by reducing the spot size of the laser beams while target compressing. In this paper, a novel optical zooming scheme is proposed, which employs a focusing grating to focus the broadband laser pulse, changing the spot size on the target within single beamlet. Experimentally, a focusing grating with clean aperture of 40-mm × 40-mm placed after the collimated light successfully realized the peak-valley of defocusing wavefront distribution of 0.73 µm as the wavelength ranging from 1052.43 nm to 1053.23 nm. Extended to the full-sized focusing grating with laser beam of 360-mm × 360-mm, it is derived that the focal spot reduction reaches to 21.8% with the 3rd harmonic light ranging from 350.81 nm to 351.08 nm, decreasing from 375 µm to 294 µm with 300 µm shaping continuous phase plate.