| 摘要 |
PROBLEM TO BE SOLVED: To make detectable a signal up to one having a high frequency component by improving the high frequency characteristics of a detected signal in an electrical index method. SOLUTION: A beam shield 27, which has been conventionally connected directly to an anode, is connected to the anode through a resistor R1 for improving characteristics. Thereby, shunt effect caused by stray capacities C0, C1 is alleviated, and high frequency characteristics of an index detecting signal is improved without lowering a signal amplitude (signal level). At this time, the shielding function itself of an electron beam by the beam shield 27 is not impaired at all. COPYRIGHT: (C)2004,JPO |
