提出了一种通过扫描滤波来提高啁啾脉冲对比度的方法，并分析了该方法的原理。与传统的非线性滤波技术不同，扫描滤波方法消除预脉冲时，选通原理是基于光的频率而不是强度。以电光双折射扫描滤波器为例，说明了扫描滤波法的具体应用。通过数值模拟及实验研究，发现电光双折射扫描滤波法可以有效地消除主脉冲以前几百ps的预脉冲，并且主脉冲同时还能保证较高的透过率。

A method using scanning filter to improve the contrast of chirped pulse is proposed, and the principle of this method is analyzed. The scanning filter is compared with the existing pulse-picking technique and nonlinear filtering technique. The scanning filter is a temporal gate that is independent on the intensity of the pulses, but on the instantaneous wavelengths of light. Taking the electro-optic birefringence scanning filter as an example, the application of scanning filter methods is illustrated. Based on numerical simulation and experimental research, it is found that the electro-optic birefringence scanning filter can eliminate a prepulse which is several hundred picoseconds before the main pulse, and the main pulse can maintain a high transmissivity.