Friday August 24, 2012
“K2: A Super-Resolution Electron Counting Direct Detection Camera for Cryo-EM”
Christopher Booth, Product Manager Life Sciences, Gatan, Inc.
Directly-illuminated silicon-based detectors have great promise for improving resolution and sensitivity over levels so far achieved with indirectly coupled, scintillator-based cameras. The reduced electron scatter of silicon, the elimination of intermediate optics and the very high-gain detection of incoming electrons yield a significant increase in resolution and sensitivity as measured by DQE. Beyond this, the electron-energy-converting element can be thinned to reduce backscatter without a sacrifice in either sensitivity or resolution.
Gatan, Inc., in collaboration with Lawrence Berkeley National Lab and members of the Howard Hughes Medical Institute, has developed a detector capable of acquiring electron-counted images under typical cryo-EM microscope conditions. A 3840 x 3840 sensor is read out at 400 frames per second and images are processed in real time to identify individual electron events. The sensor is thinned to allow the electron beam to pass through the sensor without backscatter. Small-feature CMOS technology is combined with proprietary radiation hardening measures to provide a sensor lifetime of greater than 5 billion electrons per pixel.