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.
|Number of pages||8|
|Journal||Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms|
|Publication status||Published - 2021 Jun 1|
- Automatic beam focusing
ASJC Scopus subject areas
- Nuclear and High Energy Physics