地基光学望远镜对天观测时, 大气湍流扰动引起星光波前畸变将导致其实际分辨率远低于物理极限, 这是急需解决的科学技术问题。采用钠信标激光激发海拔 80～105 km 大气电离层中的钠原子可产生高亮度的钠导引星, 可作为信标探测大气对光波的扰动, 再利用自适应光学技术进行校正, 能使望远镜克服大气扰动影响, 获得近衍射极限的分辨率。介绍了钠信标激光的特性与国内外研究进展, 尤其是中国科学院理化技术研究所激光物理与技术研究中心研制的钠 D2 线双峰谱型匹配的微秒脉冲钠信标激光器及其在大型望远镜上的应用情况。

The spatial resolution of the large ground-based optical telescope is far below its diffraction limitation because atmospheric turbulence distorts light waves from the observed space objects, which is a critical scientific and technological problem to be solved urgently. Using sodium beacon laser to excite sodium atoms in the upper atmosphere at an altitude of 80～105 km can create a high brightness sodium guide star, which can be used as a beacon to detect the wavefront aberration caused by atmospheric turbulence. As the wavefront aberration can be corrected by using adaptive optics system, the imaging resolution of large ground-based telescope will be significantly improved to be near its diffraction limitation. The development of sodium beacon laser is described in detail, especially the micro-second pulse sodium beacon laser with spectral format matched to the mesospheric D2 line developed in Research Center for Laser Physics and Technique, TechnicalInstitute of Physics and Chemistry, Chinese Academy of Sciences, as well as its successful application in some large ground-based optical telescopes.