提出了一种基于光谱色散原理调节激光相干长度的固体激光器。采用传统色散元件（光栅和多块三角棱镜）组成相干长度调节模块，通过将其置于激光谐振腔内代替一面腔镜，利用棱镜的扩束特性和光栅的色散特性实现对激光相干长度的连续调节。以NdYAG晶体作为增益介质，搭建激光谐振腔，进行了相干长度调节实验，得到了功率稳定性小于0.5%，相干长度调节范围为10~50 cm的1064 nm输出激光。理论及实验结果验证了输出激光的相干长度与调节模块中棱镜组的扩束倍率存在良好的线性关系。

A coherence length tunable solid-state laser based on the spectral dispersion principle is reported. A grating and several right-angle prisms are taken as the coherence length tunable module, which is then put in the laser resonant cavity to replace a mirror. The beam expanding characteristics of prisms and the dispersion characteristics of the grating are used to continually tune the coherence length of the laser. A resonant cavity based on NdYAG is established. An output laser of 1064 nm with power stability less than 0.5% and tunable coherence lengthes from 10 cm to 50 cm are achieved. Both the experimental results and the theoretical analysis show that there is a good linear relationship between the coherence length and the magnification of prism expander.