Hitachi, Ltd.

Yasushi Saito

Masahide Okumura

Toshihiro Furuya

Shoji Kamimura

Seishiro Sato

A charged particle apparatus wherein a charged particle beam irradiates an object to be observed and secondary emissions such as secondary electrons thus emitted from a surface layer of the object are detected. A signal indicative of the detected secondary emissions is applied to a control grid of a cathode ray tube to modulate an electron beam irradiating a fluorescent screen thereof. A detector detects the electron beam intensity of the cathode ray tube and minimum and maximum or peak values of the detected electron beam intensity are compared with predetermined reference signals to obtain deviation signals indicative of the difference therebetween. The signal applied to the control grid of the cathode ray tube is controlled in accordance with the deviation signals.

SEM having D-C bias of video signal controlled by maximum and/or minimum

A condenses lens system condenses an elctron beam onto a specimen. The electron beam thus transmitted through the specimen is magnified by a magnifying lens system. The magnified electron beam is projected onto a fluorescent screen, and the image of the specimen is visually observed. The quantity of electrons per unit area in the magnified electron beam is detected by an electron beam detector. In response to the detected signal, the condenser lens system is controlled so as to make constant the quantity of electrons per unit area in the magnified electron beam.

Electron microscope

A beam of electrically charged particles for illuminating a specimen is deflected by a deflection means so that the specimen is scanned with the beam bi-dimensionally. The information signal thus produced by the specimen is detected by a detector means and fed to a display apparatus incorporating therein another deflection means. The information signal is deflected by the latter deflection means to scan the display screen and is displayed thereon as an information image. A wave form of a signal produced in the latter deflection means is detected by a wave form detector means, the output of which is applied to the first mentioned deflection means to thereby deflect the electrically charged particle beam with a signal having a wave form similar to the detected one.

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Mito, Japan

Yasushi Saito