Applications of pixel detectors to electron microscopy

There is a compelling need for developing high performance electronic detectors due to the increasing levels of automation in electron microscopy and requirements for large numbers of new biological structures to be studied. CCD-based detectors, which have many desirable properties, have become very well established, particularly for electron crystallography. There are, however, some shortcomings in the present generation of CCD detectors, e.g. poor spatial resolution relative to film, which make them less attractive for high-resolution imaging. Direct detection semiconductor detectors, which avoid the intermediate step of energy conversion into visible light, offer the prospect of improved resolution, though with certain other limitations. Preliminary results obtained by imaging 60 and 120 keV electrons in Medipix1, a hybrid pixel detector (64×64 pixels, 170 μm square) developed by the Medipix collaboration, are presented. A number of improvements to the design would lead to a viable detector for electron microscopy.