Optical zoom system for a light scanning electron microscope

An optical zoom system for use in a confocal light scanning electron microscope with point plotting light source distribution and having an illuminating beam path and an objective for capturing an object to be imaged, the illuminating beam path having an illuminating beam path entrance pupil, and the objective having an objective entrance pupil, the optical zoom system being adapted for positioning in the illuminating beam path in front of the objective, the optical zoom system comprising:

• optical zoom entrance and exit pupils;
• means for adjusting the image magnification;
• means for adjusting the distance between the optical zoom entrance pupil and the optical zoom exit pupil in such a manner that an axially varying pupil position of the entrance pupil of the objective can be equilibrated;
• and
• means for maintaining the position of the objective entrance pupil while the means for adjusting the image magnification and the means for adjusting the imaging length are being adjusted,
• whereby the optical zoom system produces an intermediate image of the object and images an entrance pupil of the illuminating beam path with at least one of a variable magnification and a variable imaging length into an exit pupil.

A confocal scanning electron microscope, comprising:

• scanning means for guiding an illumination beam in the form of a point group over an object to be imaged,
• an illuminating beam path having an illuminating beam path entrance pupil,
• an objective for capturing the object to be imaged, the objective having an objective entrance pupil, and
• an optical zoom system adapted positioned in the illuminating beam path in front of the objective and including:
• optical zoom entrance and exit pupils;
• means for adjusting the image magnification;
• means for adjusting the distance between the optical zoom entrance pupil and the optical zoom exit pupil in such a manner that an axially varying pupil position of the entrance pupil of the objective can be equilibrated;
• and
• means for maintaining the position of the pupil while the means for adjusting the image magnification and the means for adjusting the imaging length are being adjusted,
• whereby the optical zoom system produces an intermediate image of the object and images an entrance pupil of the illuminating beam path with at least one of a variable magnification and a variable imaging length into an exit pupil.