针对平行光栅对结构的压缩器和圆形入射光束，建立了光栅拼缝所引起的光谱剪切的数学模型，并模拟了该光谱剪切对压缩脉冲信噪比的影响。与双曲正割型脉冲相比，光栅拼缝对高斯型脉冲信噪比的影响较小。随着光栅拼缝宽度的减小与光束口径的增大，压缩脉冲信噪比得到提高。对于确定的拼接光栅压缩器和光束直径，当脉冲中心波长与光谱剪切中心波长（受到光谱剪切作用的波段的中心波长）相等时，可以得到最高的压缩脉冲信噪比。

The model of spectral clipping due to the tiled-grating gap of parallel grating pair compressor is established for the circular input beam, and the signal-to-noise ratio caused by the spectral clipping is simulated. Compared with sech2 pulse, the impact of tiled-grating gap on the signal-to-noise ratio of Gaussian pulse is less serious. With the tiled grating gap width decreasing and the beam diameter increasing, the signal-to-noise ratio of the compressed pulse can be improved. For a certain tiled-grating compressor and beam diameter, the highest signal-to-noise ratio is available with the central wavelength of the pulse equal to the central wavelength of the spectral clipping (the central wavelength of the wave band clipped by the tiled-grating gap).