Dynamic focusing technique with magnification adjustment in an electro-optical lense

Abstract

In a scanning electron microscope, secondary electrons emitted from the specimen are collected at PMT, later being converted into electron signal to form an image. Usually, most surface perpendicular to the electron beam can be easily measured, however, side surface is not possible to be measured without rotating the specimen. With this forceful rotation (tilt), the original focusing depth is changed, which makes the image blurry or mismatched with original specimen. In this article, an adjustment technique is introduced, yielding the consistent image acquisition for various changes of focusing depth due to the specimen tilting.