The CM120-Biofilter: Digital Imaging of Unstained Specimen, a Comparison of Zero-Loss and Unfiltered Images
A new system for energy-filtered electron microscopy (EFTEM) has been developed, adapted for the study of life science specimens. Attention has been given to integration, ease of use and the typical problems encountered while investigating unstained and cryo-specimens. Low-dose, cryo-capabilities and a high contrast objective lens have been combined with an imaging energy filter, digital image recording with phosphorus scintillator and advanced image processing capabilities. The CM120-BioFilter is an integration of the CM 120-BioTWIN with the Gatan post-column imaging filter GIF100. The BioTWIN objective lens (Cs=6.2 mm, f=5.9 mm) is optimized for high-contrast imaging. The GIF100 is a computer-controlled, second- order corrected energy filter with a cooled multiscan CCD for digital image recording. Improvement of the contrast can be achieved if inelastically scattered electrons are removed. A comparison of zero-loss filtered and unfiltered images from unstained specimens is presented.The contrast of thick, unstained specimens is limited by the high amount of inelastic scattering. Images from thick sections of unstained spleen tissue shown in Fig. 1 are compared by means of mean and standard deviation of multiscan CCD data.