Method and apparatus for measuring degree of vacuum in an electr

Details Method and apparatus for measuring degree of vacuum in an electr Method and apparatus for measuring degree of vacuum in an electr

1987-07-07

1989-02-07

Anderson, Bruce C.

Radiant energy

Inspection of solids or liquids by charged particles

250307, 250310, 250311, 250397, G21K 100

Patent

active

048033561

ABSTRACT:
The present invention comprises disposing an electrode group consisting of an anode and cathodes provided on both sides of the anode at a portion where the degree of vacuum in an electron microscope is to be measured closing in thermal electrons between the electrode group and a magnetic field forming lens systems such as objective lens system, condenser lens system and the like of the electron microscope, collecting a gas ionized by the thermal electrons closed therebetween to measure an ionic current, thereby realizing measurement of a degree of vacuum on a sample specimen part or thereabout without deteriorating a performance of the electrons microscope. For generating the thermal electron, for example, an observing electron beam of the electron microscope is collided with cathodes of the electrode group. For measuring the degree of vacuum on the sample specimen part of thereabout, the anode is disposed between an objective lens pole piece and a sample specimen holder stage and the objective lens pole piece and the sample specimen holder stage are used as cathodes so that the degree of vacuum can simply be measured thereby.

REFERENCES:
patent: 4587433 (1986-05-01), Farley

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