Patent ID: 6930312

Claim:
A method of correcting aberrations in a charged-particle beam instrument having: an aberration corrector fitted with four stages of multipole units each having plural pole elements to which at least octupole component-activating potentials for correcting third-order aperture aberrations in a beam of charged particles are applied; an objective lens mounted on a rear side of the aberration corrector and acting to focus the accelerated beam of charged particles onto a specimen; a control portion for controlling the activation potentials applied to the pole elements of the stages of multipole units; and an operation portion for varying one of an accelerating voltage of the beam and a working distance that is a distance between the objective lens and the specimen; operating the control portion, said method further comprising the steps of: adjusting a resultant magnification of the aberration corrector and the objective lens when one of the accelerating voltage and the working distance is varied by the operation portion; and maintaining constant the octupole component-activating potentials applied to the pole elements of at least one stage of the multipole units.