为了更好地研究神光Ⅲ原型实验中激光与等离子体相互作用产生的散射光，研制了新的全孔径背向散射诊断系统。该系统根据布里渊散射与拉曼散射的性质区别，使用二向色镜对散射光进行分光提纯，采用真空滤波器、挡光板、高反滤波片以及改变倍频晶体角度等进行消杂光处理，进而减少杂散光对测量结果的影响。同时，该系统采用特制的全口径大光斑激光器模拟打靶散射光对光路透过率进行标定。实验结果表明: 新的全孔径背向散射诊断系统工作状态稳定，明显减少了杂散光的影响，所测数据更加真实可靠。

In order to have an investigation for the scattering light produced by laser plasma interaction at Shenguang Ⅲ laser facility, a new full-aperture backscatter light diagnostic system was developed. According to the properties of Brillouin scattering and Raman scattering, the system gives multiple light splitting and purification, and avoids the effect of stray light. Thus the system has a calibration for the damping factor by using a tailor-made full-aperture laser. The results show that the new full-aperture backscatter light diagnostic system can work stably, and can significantly reduce the effects of stray light. So compared with the original system, the measured data of this system are more reliable.