以常见的三种类型的激光束，即非稳腔产生的环形激光束、稳定腔产生的高斯光束以及多路高斯光束的相干合成光束作为研究和讨论的对象，针对涉及能量集中度的应用，分析了现有各种评价指标的优缺点和适用性，并对评价指标定义中若干关键问题进行了分析计算。结果表明，激光束的亮度或靶目标上光斑能量密度是评价激光系统效能发挥的重要评价参数，该评价指标不仅可以用于衡量同一激光系统的光束质量，也可以客观地评价不同激光系统间性能优劣。

According to application purposes concerning focusability of laser energy, three kinds of lasers, i. e., the annular lasers generated from unstable resonators, Gaussian lasers generated from stable resonators and combined lasers of several Gaussian lasers are taken as analyzing objects. The advantages and drawbacks of beam quality parameters available are discussed, and some key issues on definition of beam quality are calculated and analyzed. The results show that, the parameter of laser brightness or laser energy density on the target is a very important standard for evaluating the performances of laser systems, which is suitable for measuring performance of the same system, as well as different systems objectively.