FOCUSING DEVICE FOR SCANNING ELECTRON MICROSCOPE

摘要

PROBLEM TO BE SOLVED: To simplify focusing during high-powered observation by adjusting the focus of an image on the center of a observing monitor for obtaining an image of a normal-focus. SOLUTION: This scanning electron microscope 1 is constituted so that X, Y deflected signal generated by a deflection circuit 2 mounted in the scanning electron microscope 1 and a focus control signal generated by a focus control circuit 3 are input to a focus correcting circuit 4, and focus control correction associated with an image scanning speed and magnifying power is performed and the result is output when an auxiliary function for the focus is on for controlling the focus coil 5 so that parts except the vicinity of the center are set in insufficient focus if normal-focus is obtained.