针对高能窄带激光系统对光谱纯度检测的需求，提出通过精确测量激光光谱能量分布情况分析光谱纯度的方法，并进行了相关实验研究。该光谱纯度检测装置主要由中阶梯光栅、精密移动刀口、灵敏功率计等组成，实验利用该装置分析了复合腔结构准分子激光系统输出激光的光谱纯度，实验结果表明通过精确测量激光中各光谱成分所占的能量比例可实现光谱纯度的检测。该光谱纯度检测装置结构紧凑、成本较低、测量准确度高，在高能窄带激光系统搭建过程中具有重要的应用价值。

For the demand of spectral purity detecting in high-energy narrow-line width laser system, a method of spectral purity analysis by measuring the spectral energy distribution is reported and experimentally studied. The spectral purity analysis device is mainly composed of echelle grating, moveable blade, sensitive power meter,etc. The output spectrum of excimer laser system with a compound cavity is analysed by using this device. The experimental results show that the spectral purity detection can be achieved by accurately measuring the energy ratio of the spectral components. The spectral purity analysis device has the advantages of compact structure, low cost and high accuracy, which has important application in the building process of high-energy narrow-linewidth laser system.