| 摘要 |
PURPOSE:To remove easily astigmatism and enable stereoscopic observation of a sample with a big solid angle and high resolving-power by correcting astigmatism synchronizing with two-dimensional scanning of the means for two- dimensionally scanning electron rays refracted on the sample surface. CONSTITUTION:The image observation is performed by two-dimensionally scanning electron rays on a sample 4 by means of a deflector 6 for scanning while being electrically controlled by a signal generator 9 for scanning and the signal generator 10 for refraction synchronized therewith. At the same time, an astigmatism correction signal generator 11 is made to work for correcting astigmatism of electron rays generated on the sample surface through the astigmatism corrector 7 in synchronization with the genrators 9 and 10. Said correction signal works as a function of the scanning positions (X and Y) while being + or -corresponding to + or - of a refraction angle t. Thereby, astigmatism at the time of measurement can be removed thus to obtain high resolving-power. |
