APERTURE DEVICE OF OPTICAL APPARATUS

PURPOSE: An aperture device of an optical apparatus is provided which prevents decrease of the resolution by preventing coulomb interaction of electron beams passing through beam apertures of a beam passing part even if a beam current is increased. CONSTITUTION: An aperture device of an optical apparatus is constructed in a manner that a beam passing part(22) is formed at the center of a beam shielding part(23). The beam passing part is configured of a plurality of beam apertures(21). The coulomb force of electron beams that pass through the beam apertures of the beam passing part is reduced so that high resolution can be obtained with the same beam current. The diameter of each beam aperture is smaller or identical than or to the height of the beam apertures. Each of the beam apertures has a circular or rectangular shape.