成像型任意反射面速度干涉仪的散斑抑制

Speckle suppression in imaging velocity interferometer system for any reflector

成像型任意反射面速度干涉仪(VISAR)是激光驱动聚变实验中诊断冲击波速度的重要设备。由于采用了激光照明靶面的方式,所获得的速度条纹图中不可避免有激光散斑的干扰,严重影响动态条纹的质量。介绍了该系统的激光散斑形成原因和散斑对速度分析的影响,提出了一种频谱面滤波的方式去除高频散斑噪声的方法,并通过搭建散斑光路、合理设置滤波孔位置和大小,对该方法进行了验证。结果表明,该方法对影响条纹图的高频散斑噪声具有抑制作用,适合应用于成像型VISAR系统。

Imaging velocity interferometer system for any reflector （VISAR） is a typical facility for diagnosing shock wave velocity in ICF experiments. Due to the using of lighting laser in the system, the obtained velocity streak images are affected by laser speckle, and the velocity analysis is influenced for this reason. The formation reason of the laser speckle in the system and the effect in velocity analysis are introduced in the paper. A lowpass filter located at the Fourier frequency plane of the imaging system is used to filter the high frequency speckle noise. An optical path of the interferometer used in the VISAR is put forward and the real path is simulated. The results shown in the paper indicate that the filter used in the system obviously suppresses the speckle noise in the imaging VISAR.