| 摘要 |
PURPOSE:To execute easily and exactly a measurement by deriving a beam spot diameter from a square wave current for oscillating a beam spot. CONSTITUTION:A beam spot diameter measuring device 2 is placed on the center area on the outside face of a face panel 7 of a sample image receiving tube 1. The measuring device 2 is provided with a U-shaped magnetic material piece 3, a coil 4 wind-installed to its two leg parts 3a, 3b, a variable square wave current generating source 5 connected to the coil 4, and a magnifying lens 6. An electronic beam going toward a phosphor film area 13 from an electronic needle 11 is oscillated by making a variable square wave current flow to the coil 4 and generating an alternating deflection magnetic field 10. As a result, two beam spots 14 are generated in two places like time division. Subsequently, magnitude of a square wave current in case when both beam spots are armoured is measured by adjusting an output current of the current generating source 5. Basing on this measured value, a beam spot diameter is obtained. |
