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A method for measuring large aberrations up to second order (defocus, 2-fold astigmatism and axial coma), which uses a through-focus series of Ronchigrams, is proposed. The method is based on the principle that line-focus conditions in Ronchigrams can be locally detected and low-order aberrations can thereby be measured. The proposed method provides auto-tuning of large low-order aberration; in particular, iterative aberration measurement and correction reduce low-order aberrations from several thousand nanometers to less than a few hundred nanometers, which can be handled by conventional fine-aberration tuning methods. [ABSTRACT FROM PUBLISHER]

We developed a 1 MV field-emission transmission electron microscope. This paper reports details and specifications of the instrument. The microscope was designed to obtain a bright and coherent electron beam by using the field emission gun equipped with a pre-accelerating magnetic lens and the highvoltage power supply with high stability (0.5 ppm min−1). Using this microscope, the brightness of 1.8×1010 A cm−2 sr−1 and the lattice resolution of 49.8 pm were attained. [ABSTRACT FROM PUBLISHER]

A method of confirming information transfer in spatial frequency regions higher than 10 nm-1 by the objective lens of an electron microscope is introduced. Two electron-diffraction waves, 000 and hkl, from a crystalline specimen are selected by an objective aperture inserted asymmetrically on the back-focal plane, and a lattice image is observed at appropriate defocus values to prove that information corresponding to the spatial frequency of hkl diffraction has been transferred. We confirmed that information for 15.6 nm-1 (0.064-nm-spacing fringes in real space) and less could be transferred in a 1-million-volt field emission electron microscope. [ABSTRACT FROM AUTHOR]

An electron biprism for a 1 million-volt field-emission electron microscope was developed. This biprism is controlled similarly as a specimen holder so that it can be driven and rotated precisely and is tough against mechanical vibration and stray magnetic field. We recorded the maximum number of interference fringes by using this biprism in order to confirm the overall performance as a holography electron microscope, and obtained a world record of 11 000 interference fringes. [ABSTRACT FROM AUTHOR]