PURPOSE: To make the degree of vacuum in and around a sample part or the like inside a scope measurable without deteriorating the capacity of the electron microscope, by setting up the specified electrode group in a vacuum measuring spot, confining a termion inside, and measuring the degree of vacuum upon collecting and measuring the gas ionized.
CONSTITUTION: An electrode group consisting of an anode 3 and the cathode installed at both sides of this anode 3 is set up in a vacuum measuring spot inside an electron microscope. And, a thermion is confined between the electrode group by magnetic field forming the electrode group and a lens system of the electron microscope, and the gas ionized by the termion confined is collected, measuring an ion current. That is to say, a quantity of the ionized gas is measured by a micro-ammeter 7 or the like as an ion current, and since this ion current and gas pressure are expressed with a fixed formula, pressure in and around a sample part or the like, namely, vacuum is made measurable. With this constitution, the degree of vacuum inside the electron microscope in and around the sample part or the like can be measured without deteriorating capacity of the electron microscope.
HASHIMOTO MOTOYUKI
NISHIMURA EIICHI
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