The invention relates to a charged particle apparatus equipped with a charged particle source (202) for emitting a beam of charged particles, downstream of said beam followed by condenser optics (208), followed by a sample position, followed by an objective lens (214), followed by imaging optics (216), and followed by a detector system (218, 224), in which, between the objective lens and the detector system, a first stigmator (250) is positioned for reducing astigmatism when imaging a sample (210) on the detector system and a second stigmator (252) is positioned for reducing astigmatism when the diffraction plane is imaged on the detector system, characterized in that a third stigmator (254) is positioned between the objective lens and the detector system, as a result of which a third degree of freedom is created for reducing the linear distortion.;The invention further relates to a method of using said three stigmators, the method comprising exciting the first stigmator to reduce astigmatism when imaging the sample and exciting the second stigmator to reduce astigmatism when imaging the diffraction plane, characterized in that the method comprises exciting the third stigmator to reduce the linear distortion.
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