为研究空间光强分布不均匀对二阶单次自相关脉宽测量的影响,分析了二阶单次自相关测量脉宽的原理,重点讨论了周期性调制和局部暗区/强区对脉宽测量的影响,用数值模拟的方法分析了不同调制形式以及不同调制度可能引起的测量误差,并进行了初步的实验验证。结果表明,当近场空间光强分布有周期性条纹状调制时,在一定范围内条纹越稀疏,调制度越大,CCD的测量值偏差越大; 当近场有局部暗区(强区)调制时,在暗区宽度不大的前提下,暗区宽度越宽或强区宽度越窄,调制度越大, CCD的测量值偏差越大。

To study the influence of the spatial irregular distribution of the fundamental beams on the measurement of pulse duration of the second-order autocorrelator, the principle of single-shot second-order autocorrelator was analyzed. The influences of periodical modulation and local dim /bright region on the measurement of pulse duration were discussed numerically. The results show that when the intensity was modulated periodically, at certain extent the higher the modulation and the sparser the strips, the bigger the autocorrelator measurement warp will be. When the intensity was modulated by local dim /bright region and the dim region is not large, the wider the dim region or the narrower the bright region, as well as the higher the modulation, the bigger the autocorrelator measurement warp will be.