| 摘要 |
PURPOSE:To improve the convergence detecting accuracy by attaching a slit with a hole to the upper face of a phosphor, arranging a photodetector corresponding to the hole, in a fluorescent state detecting part, and also making the fluorescent substance of the phosphor correspond to the hole and the photodetector. CONSTITUTION:In a fluorescent light emission detector 11 which is placed in the beam photodetecting part of an electron beam welder in order to detect its converging state, a slit 21 having a hole 22 is attached to the upper face of the phosphor 17, and the photodetector 20 corresponding to the hole 22 by (1:1) is arranged in a fluorescent state detecting part 18. Also, the fluorescent substance 23 of the phosphor 17 is arranged so as to correspond to the hole 22 and the photodetector 10 by (1:1). Only an electron beam which is through the hole 22 makes the corresponding fluorescent substance 23 emit a light, and it is detected by the photodetector 20, therefore, an influence by an irregular light emission of the fluorescent substance 23 is eliminated, and the electron beam convergence detecting accuracy is improved.
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