We have developed an automatic beam-focusing system to reduce the experimental configuration time for a sub-micrometer-scaled beam probe of MeV ions with various analytical applications. Parasitic aberration due to misalignment and astigmatism must be eliminated or minimized to obtain an ideal beam spot size of less than 1 × 1 µm², because astigmatism from excitation error and axial misalignment broaden the beam. The system involves a two-stage process of contrast and phase-difference detection that includes an automated minimization algorithm for astigmatism. The process can identify misalignments of axial rotation by measuring the line profiles of a fine mesh grid. The contrast method focused a proton microprobe to approximately 1 μm² within 30 min, without the need for manual control when rotational misalignment was not present, while the phase-difference method successfully reduced the rotational error of lenses.

我们开发了一种自动束聚焦系统，以减少具有各种分析应用的MeV离子亚微米级束探针的实验配置时间。为了获得小于1×1 µm ²的理想束斑尺寸，必须消除或最小化由于未对准和像散引起的寄生像差，因为激发误差和轴向未对准引起的像散会加宽光束。该系统涉及对比度和相位差检测的两阶段过程，该过程包括用于散光的自动最小化算法。该过程可以通过测量细网格的线轮廓来识别轴向旋转的未对准。对比法聚焦的质子探针至约1μm ² 在30分钟内，无需旋转不对准时就无需手动控制，而相差法则成功地减少了镜片的旋转误差。