神光Ⅱ升级装置远场准直系统研究

Far field auto-alignment system used in SG-Ⅱ-Up system

用于实现光束调整的自动准直系统不仅是保证高功率激光装置高效、安全、可靠运行的关键子系统,同时也是保证光束近场和远场质量的关键要素之一.通过巧妙的光栅制作和照明成像系统设计,实现了高精度、模块化的远场准直系统.其特点在于利用光栅的衍射特性,实现了远场焦斑和基准的同时离轴取样.此系统在神光Ⅱ升级装置预放系统的实验结果表明,其光栅基准的复位精度优于8μm,准直过程中基准的抖动低于0.59μm;准直完成后,焦斑中心和基准中心的最大偏差优于10μm.此系统在实现了高精度取样、准直的前提下,不仅降低了对成像系统稳定性的要求,同时节省了巨大空间,为保证神光Ⅱ升级装置的顺利研制,以及实现整个系统的集成化、模块化提供了有力支撑.

The auto alignment system,which is used for the beam adjustment in high power laser system,is not only the key subsystem ensuring the routine operation effectually and safely,but also the key element involved in improving the far-field and near-field beam quality.Based on a skillful design of the grating and illumination-image system,a far field alignment system is realized.This system,which is based on a diffraction function of the grating,is characterized by the high performance and the simultaneous off-axis sample of the focus and the reference.The results,which are obtained when the system is used in pre-amplifier system of the SG-Ⅱ-Up,show that the reposition accuracy of the grating reference is better than 8μm,the jitter amplitude is less than 0.59 μm.After the alignment,the deviation of the beam focus from the grating reference is no more than 10 μm.