US 4,788,425 AGranted

Optical axis adjusting apparatus for electron microscope

AssigneeHitachi, Ltd.

InventorHiroyuki Kobayashi

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Abstract

An optical axis adjusting apparatus for an electron microscope for aligning the optical axis of a radiation lens system and the optical axis of an imaging lens system with each other is disclosed. A magnetization current of an objective lens or an accelerating voltage is changed stepwise and an image by the electron microscope is taken in for each change step. The taken-in images are integrated and averaged to produce a blurred image which is in turn stored in an image memory. While displaying this blurred image on a CRT monitor together with a cross marker, the amount of deflection of an electron beam inputted from a deflection input device for moving the cross marker in an interlocking manner is changed so that a cross point of the cross marker is positioned to coincide with a current center or voltage center recognizable from the blurred image displayed. Thereby, the cross marker is moved by an amount equal to the amount of movement of the image due to the change of the deflection amount but in a direction reverse to the direction of the image movement.

Claims12

Dependent claims

An optical axis adjusting apparatus for an electron microscope for aligning an optical axis of a radiation lens system and an optical axis of an imaging lens system with each other, said apparatus comprising:

an electron gun applied with an accelerating voltage for emitting an electron beam;
said radiation lens system for irradiating a specimen with the electron beam from said electron gun;
an electron beam deflector for providing a predetermined deflection to the electron beam;
said imaging lens system for forming an enlarged image of said specimen, said imaging lens system including an objective lens;
display means for displaying the enlarged image;
means for changing one of a magnetization current of said objective lens and said accelerating voltage;
image taking-in means for taking in a plurality of images in the course of the change by said changing means and storing an image in a superimposed form of said plurality of images;
image output means for causing the image stored in said image taking-in means to be displayed on said display means;
and
optical axis adjustment means for aligning the optical axis of said radiation lens system and the optical axis of said imaging lens system with each other on the basis of the image displayed on said display means.

7 more elements

Dependencies are inferred from the claim text.