本文讨论了具有一定频谱宽度的超短激光脉冲经过一对平行光栅后的空间展宽特性. 首先应用经典的光栅方程推导了脉冲光经过光栅对后在空间上展宽的计算公式. 结果表明随着光栅对之间距离的增加，输出脉冲光斑的横轴长度会随之增加，理论结果与实验结果基本一致.最后利用光纤光谱仪逐点测量了展宽后脉冲光斑的空间光谱分布特性，验证了其空间啁啾特征的出现.

Spatial broadening of ultrashort laser pulses with a certain spectral width is studied after passing through a pair of parallel gratings. Firstly，the formulas for calculating the spatial broadening of ultrashort laser pulses after passing through a pair of gratings are derived by using the conventional grating equation and geometric optics knowledge. The experimental results also show that with an increase of the distance between grating pair，the transverse axis length of the pulsed spot increases and fits very well with the theoretical value. Finally，the spatial spectral distribution of the broadened pulsed spot is measured point by point by a fiber spectrometer，and the result verifies appearance of the spatial chirp characteristics.