棱镜扩束器(PBE)广泛用在准分子激光腔内光谱压窄系统中，可以有效降低光束发散角和系统内能量密度。为了实现窄线宽激光输出并降低腔内损耗，需要对棱镜扩束器的棱镜个数、单棱镜扩束倍数和棱镜顶角进行优化设计。根据棱镜扩束倍数的理论，数值分析了入射角、顶角和出射角对棱镜扩束倍数的影响，并在实验上很好地验证了扩束倍数与入射角的关系。此外，推导了激光器线宽压窄系统实现一定激光线宽输出所需的总棱镜扩束倍数。优化设计了扩束倍数M为13.3的氟化钙消色散棱镜扩束器，在此基础上，实现了0.915 pm的窄线宽ArF激光输出，实验结果与理论设计吻合。

Prism beam expander (PBE) is widely used in the spectral narrowing module of excimer lasers. The beam divergence and fluence could be reduced by the prism beam expander. The prism number, magnification of single prism and apex angle of the PBE should be optimized to improve the efficiency of the laser. Based on the magnification theory of the prism, the impact of the incidence angle, apex angle and exit angle of the prism on magnification are analyzed by numerical simulation. The dependence of magnification on incidence angle is demonstrated experimentally. Furthermore, to achieve a given linewidth of the laser, the minimal magnification of the line narrowing module is deduced. In addition, CaF2 prism beam expander with magnification of 13.3 is designed. Finally, 0.915 pm linewidth ArF laser is obtained using the designed PBE. The experimental results agree with the theoretical analysis.