Charge-coupled device (CCD) cameras have found wide application in electron microscopy. They provide much faster availability of image and diffraction data than photographic film, and this improvement in turnaround time has allowed a tremendous increase in the efficiency of specimen evaluation, microscope operation and automation, and data recording. For some types of work the data collected with a CCD is of higher quality than that recorded on film. However, the CCD performance is seriously compromised when the microscope is operated much above 100 kV, due to the decrease in efficiency of the scintillator. The higher voltages result in a decrease of the signal level and introduction of noise, as well as an increase in lateral scattering of the electrons within the scintillator, which decreases the resolution. Together these effects can produce a detective quantum efficiency (DQE) which is far below that of film, and indeed too low for work such as low-dose imaging of proteins. The use of Intermediate Voltage Electron Microscopes (IVEMs) operating at 300 - 400 kV is increasing as the many advantages of the higher accelerating voltage become more widely recognized, so the CCD performance on these microscopes is becoming more of a limitation. We are building a new CCD camera system designed to overcome the poor performance of CCD cameras on IVEMs by decelerating the electrons before they reach the camera. We mount the CCD so that it can be floated to around 200 kV, so that when the microscope is operated at 300 kV we obtain the advantages of the IVEM but the camera should perform as well as on a 100 kV microscope. Further improvements will be made to the scintillator to produce even better signal and resolution characteristics than currently available. This advance will, in turn, allow us to utilize the newest, very large format CCDs that are fabricated with smaller pixels. These adaptations will produce substantial benefits in work ranging from high-resolution structural studies of proteins and viruses to the three dimensional study of cell ultrastructure. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM075519-02
Application #
7227877
Study Section
Microscopic Imaging Study Section (MI)
Program Officer
Flicker, Paula F
Project Start
2006-05-01
Project End
2010-04-30
Budget Start
2007-05-01
Budget End
2008-04-30
Support Year
2
Fiscal Year
2007
Total Cost
$334,100
Indirect Cost
Name
Lawrence Berkeley National Laboratory
Department
Neurosciences
Type
Organized Research Units
DUNS #
078576738
City
Berkeley
State
CA
Country
United States
Zip Code
94720