1. Introduction 11.1 The ‘band gap’ in silicon 22. Principles of CCD detector operation 32.1 Direct detection 32.2 Electron energy conversion into light 42.3 Optical coupling: lens or fibre optics? 62.4 Readout speed and comparison with film 83. Practical considerations for electron microscopic applications 93.1 Sources of noise 93.1.1 Dark current noise 93.1.2 Readout noise 93.1.3 Spurious events due to X-rays or cosmic rays 103.2 Efficiency of detection 113.3 Spatial resolution and modulation transfer function 123.4 Interface to electron microscope 143.5 Electron diffraction applications 154. Prospects for high-resolution imaging with CCD detectors 185. Alternative technologies for electronic detection 235.1 Image plates 235.2 Hybrid pixel detectors 246. References 26During the past decade charge-coupled device (CCD) detectors have increasingly become the
preferred choice of medium for recording data in the electron microscope. The CCD detector
itself can be likened to a new type of television camera with superior properties, which makes
it an ideal detector for recording very low exposure images. The success of CCD detectors
for electron microscopy, however, also relies on a number of other factors, which include its
fast response, low noise electronics, the ease of interfacing them to the electron microscope,
and the improvements in computing that have made possible the storage and processing of
large images.CCD detectors have already begun to be routinely used in a number of important
biological applications such as tomography of cellular organelles (reviewed by Baumeister,
1999), where the resolution requirements are relatively modest. However, in most high-
resolution microscopic applications, especially where the goal of the microscopy is to obtain
structural information at near-atomic resolution, photographic film has continued to remain
the medium of choice. With the increasing interest and demand for high-throughput structure
determination of important macromolecular assemblies, it is clearly important to have tools
for electronic data collection that bypass the slow and tedious process of processing images
recorded on photographic film.In this review, we present an analysis of the potential of CCD-based detectors to fully
replace photographic film for high-resolution electron crystallographic applications.
Single-particle cryo-EM: alternative schemes to improve dose efficiency
