JPS58184761U - Automatic gain level control device for scanning electron microscope - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Brief explanation of the drawing]

Fig. 1 is a diagram for explaining normal signals and defective signals, Fig. 2 is a diagram for showing an embodiment of the present invention, and Fig. 3 is a diagram for illustrating output signals from each circuit. It is a diagram. 1: Electron gun, 2: Converging lens, 3: Objective lens, 4: Sample, 5: Electron beam, 6: Deflection coil, 7: Magnification control circuit,
8: Secondary electron detector, 9: Variable gain amplifier, 10: L
/Bevel straightener, 11: Mixer, 12: Switching circuit, 13:
Cathode ray tube, 14: Bad signal detection circuit, 15, 16: Scanning circuit, 17.18: Comparison circuit, 19: Upper limit level output circuit, 20: Lower limit level output circuit, 21, 22: Gate circuit, 23, 24 Nifritz Pflop circuit, 25: OR circuit, 26: Planking signal generator, 27: automatic gain level control circuit. −−−−−−1↑T−□Time− 111111Bto c−−

Claims (1)

[Scope of utility model registration request] An electron beam is scanned two-dimensionally on a sample surface, an information signal obtained from the sample during the scanning is detected by a detector, the detected signal is amplified and the level is adjusted, and the amplification and level A device comprising an automatic gain level control circuit that monitors the adjusted signal and automatically adjusts the gain and level adjustment amount of the amplifier so that the signal returns to the normal range when it deviates from a preset normal range, means for monitoring the level of the amplified and level-adjusted signal and automatically increasing the scanning speed of the electron beam at the moment the level of the signal goes out of a normal range; and a gain control circuit for automatically increasing the scanning speed of the electron beam. means for automatically restarting scanning of the electron beam from the original scanning position at the original scanning speed as soon as the level control is completed; and means for automatically restarting the cathode ray tube during the gain level control period by the automatic gain level control circuit. 1. An automatic gain level control device for a scanning electron microscope, comprising means for blanking the scanning electron microscope.