中文摘要：

243 nm是氢原子1S—2S能级跃迁光谱波长。本文利用Pound-Drever-Hall稳频技术将972 nm光栅反馈外腔半导体激光稳定在一个高精细度低膨胀系数的超稳法布里-珀罗腔上，通过锥形放大器放大和腔内两次共振增强倍频得到243 nm激光，最终实现用于探测氢原子1S—2S双光子跃迁的243 nm窄线宽激光。

英文摘要：

The two-photon spectroscopy of 1S—2S transition in atomic hydrogen needs a narrow linewidth laser at the wave-length of 243 nm. In order to reduce the linewidth to several tens hertz level, a free operation CW ECDL 972 nm laser has been locked to a high fineness ultralow expansion reference cavity by using the Pound-Drever-Hall technique. And the part of 972 nm laser output is set into the tapered amplifier and the two enhanced doubling frequency stages to obtain the output of purple light at 243 nm. It is estimated that such a narrow linewidth laser system at 243 nm can be used well in the detection of the 1S—2S transition of hydrogen.