A contribution to the unsolved problem of a high-tilt fully eucentric goniometer stage

A design is presented of a high-angle fully eucentric tilting stage (±45. ±23° around two orthogonal axes) for a transmission electron microscope. The concurrent design of suitable objective-lens pole pieces has been made in order to get the best compromise between electron optical performances and the difficulties inherent in the construction of the stage. A resolution of 3 A is calculated at an accelerating voltage of 200 kV. The design exploits the space both above and in the middle of the objective pole-piece assembly: the space above is used to house the stage, while the space in the lens gap serves the purpose of loading the specimen. In this way the incorporation of an x, y, z specimen traverse stage inside the high-tilt universal suspension appears to be a practical proposition. Although the details of the stage have been worked out with the JEOL JEM 100 and 2000 series of electron microscopes in mind, the working principles of the design can be applied to other types of microscopes.