A novel specimen stage permitting high-resolution electron microscopy at low temperatures

Abstract

Low-temperature specimen stages are advantageous for various applications of electron microscopy. The problems arising in the construction of such devices are surveyed and solutions involving some new principles and methods are indicated. These are discussed for the case of a helium-cooled stage constructed for a Hitachi high-voltage electron microscope. This device allows cooling in the temperature range from 300 to 5 K under full preservation of the optical resolution of the microscope. The fundamentals of the construction may easily be applied to the construction of cooling stages for other microscopes. The new cooling stage presented here has the following main features. Highly concentric mounting is ensured by using isolating hollow cylinders as supports. The specimen can be tilted +or- 30 degrees in each direction and can be translated +or- 1 mm in all directions perpendicular to the electron beam. Specimen exchange is simple and requires merely the insertion of a light specimen holder into the stage via an airlock mechanism. A vibration-free and thermally extremely stable cooling is achieved over the whole temperature range by using cold helium gas.