在几何光学近似下,研究了非稳腔中的离焦像差的演化,解析地给出了正支共焦非稳腔中离焦像差的线性修正公式。结合氧碘化学激光器的模拟结果表明:光腔的放大率越小,像差演化的影响越明显;变形镜直接放在凹面镜处的补偿效果最好。对比直接补偿,考虑像差演化的补偿可以使光束质量的β值平均降低35%。 Under the geometrical optics approximation, the evolution of defocus aberration in unstable cavity is studied, and the linear correction formula of defocus aberration in positive steady-state confocal resonator is analytically given. The simulation results with the oxygen-iodine chemical laser show that the smaller the magnification of the optical cavity, the more obvious the effect of aberration evolution. The compensation effect of the deformable mirror placed directly on the concave mirror is the best. In contrast to direct compensation, the compensation of aberration evolution can reduce the beam quality β by an average of 35%.