Embodiments of the present invention provide an apparatus employing an electron beam to expose the structure of a micro device and produce an image of the structure. The apparatus includes an electron gun producing the electron beam; an electron beam column having one or more segments that shape, focus and/or deflect the electron beams; and one or more center tubes along the electron beam column that provides a high vacuum environment for and guiding the electron beam to a target object coated with an electron sensitive resist. At least one of the center tubes is a carbon tube made of solid carbon material.