Charged particle microscope for examining a specimen, and method of determining an aberration of said charged particle microscope

A charged particle microscope for examining a specimen, comprising:

• an optics column, including a charged particle source and an illuminator for directing a beam of charged particles emitted from said charged particle source onto a specimen;
• a specimen stage positioned downstream of said illuminator and arranged for holding said specimen;
• a detector device for detecting emissions originating from said specimen in response to the incidence of charged particles emitted from said charged particle source;
• and
• a control unit with instructions saved on a non-transitory memory, the control unit is configured to:
• acquire a set of image data with the detector device during a dedicated use of said charged particle microscope, wherein the dedicated use includes navigating the specimen with the charged particle microscope and/or adjusting a focus setting of the charged particle microscope;
• process said set of image data to determine an aberration while acquiring the set of image data during the dedicated use;
• and
• adjust a focus lens and a stigmator of said charged particle microscope based on said aberration after the dedicated use.