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THE CM30-SUPERTWIN: A DEDICATED ULTRA-HIGH RESOLUTION TRANSMISSION ELECTRON MICROSCOPE MAX T. OTTEN Philips Analytical, Electron Optics Application Laboratory, Building AAE, 5600 MD Eindhoven, The Netherlands ABSTRACT The CM30-SuperTWIN Transmission Electron Microscope achieves a point resolution of 0.19 nm as shown by standard and unique TWIN lens Young's fringes diffractograms. Thanks to its concept, the instrument combines ultra-high resolution with excellent performance in numerous other operational modes, including scanning, diffraction and micro-analysis. Coma-free alignment, providing accurate objective-lens centring, is standard on the CM30. Complete microprocessor control yields ease of operation, accurate and reproducible microscope control and connection with peripheral equipment. INTRODUCTION Increasingly, the TEM is becoming an all-round research microscope, combining many techniques in a single instrument. Improvements in the design of the objective lens have reached the stage where lenses compatible with micro-analysis and scanning equal or surpass dedicated high-resolution objective lenses in performance. In the foreseeable future, microscopes capable only of high-resolution imaging will be replaced by versatile, ultra-high resolution instruments. An instrument of latter category is the CM30-SuperTWIN, combining ultra-high resolution capabilities with micro-analysis and scanning modes. THE CM30-SuperTWIN The CM30-SuperTWIN is the latest addition to Philips' CM series Transmission Electron Microscopes. The instrument can be either a TEM or a full TEM/STEM system, with the former being upgradable to STEM. Both TEM and STEM versions are compatible with micro-analysis without any compromise in ultra-high maximum accelerating voltage resolution performance. With its of 300 kV and low-Cs SuperTWIN objective lens, the microscope is dedicated to ultra-high resolution. The theoretical point resolution of the CM30-SuperTWIN is 0.20 nm, while experimental results have shown the instrument capable of achieving a point resolution of 0.19 nm. The point resolution of the CM30-SuperTWIN has been tested using an amorphous carbon foil with small oriented gold islands for calibration. Optical diffractograms clearly show that at zero Scherzer defocus [taken as 1.2*(Cs* X)1/ 2 ], the first crossing of the contrast transfer, which defines the point resolution, lies beyond 0.19 nm (Fig. 1), implying a Cs value of 0.9 mm or better. Young's fringes diffractograms (Fig. lb) are useful additions to the standard diffractograms, because they allow a better distinction to be made between information and noise. Young's fringes are obtained with two micrographs Mat. Re& Soc. Syrmp. Proc. Vol. 139. c1919 Malerials Research Society

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together in the optical diffractometer. When the micrographs have been recorded on the same area of the specimen and under exactly the same microscope conditions, they contain the same information, while the noise, being unrelated to the contrast is different. When the two transfer of the microscop