The OAM or the One Anstrom Microscope. The One-Angstrom Microscope is a mid voltage transmission electron microscope or TEM. This type of microscope is capable of producing images with sub angstrom resolution. The basic instrument is a modified TEM with a field emission electron source and an ultra twin objective lens with low spherical aberration of 0.60 mm. It has a point-to-point resolution of 1.7 Angstrom. It is known to have highly stable power supplies for the objective lens and for high voltage power produce an information limit of 0.8 Angstrom. A 2048 by 2048 pixel charge coupled device or CCD camera digitally records images from this microscope up to a maximum magnification of 38M times. The OAM microscope can operate at an acceleration voltage of either 300kV or 150 kV and can produce aberration corrected exit wave images with 0.8-Angstrom resolution. The OAM can operate several modes including Focal series restoration from lattice images, using focal-series reconstruction, Electron holography, Annular dark field TEM imaging, Energy filtered imaging and spectroscopy and Electron tomography.The images recorded at different defocus settings in this OAM contain differently phased spatial frequencies. Generating one image with sub Angstrom resolution requires extraction and combination of the correct band of frequencies from members of a focal series. For focal series reconstruction, the OAM uses software to process focal series acquired automatically from the microscope under computer control, thereby establishing the exit surface wave. This process can correct residual lens aberrations due to 2 and 3 fold astigmatism, coma, and spherical aberration.Electron holography can produce high-resolution type of images by recording images or holograms that have been multiplexed with a suitable high frequency carrier. The carrier frequency is then removed with image processing. This then yields a complex image. The complex image is corrected for the phase changes imposed by the microscope imaging system to produce the corrected image at enhanced resolution. The microscope uses an energy filtered imaging. Its 2k Gatan imaging filter or GIF can be used to map chemical elements at near atomic resolution up to less than 10 Angstrom. Images are acquired with the multiscan CCD camera and can be read under computer control. Local chemical concentrations using the OAM can be quantified using the GIF in EELS mode to access the spectroscopic signatures of light elements.
Annular dark field transmission electron microscopy imaging enables Z contrast imaging without scanning noise and with reduced sample contamination.
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