K2 Summit and K2 Base Direct Detection Camera User's Guide
20
Counted:
Each electron event results in one count in the image. The raw images are dark
subtracted, gain-normalized and processed in hardware to detect individual electrons. The
resulting summed electron counts are output as an image. In this mode, keep the beam at
low levels (20 electrons per pixel per second or less) to avoid signal loss.
figure 1-12. K2 Direct Detection palette: Counted mode
Super-Resolution:
Electron events are localized to the sub-pixel in which they occurred.
Additional processing is done to further refine the electron positions resulting in a higher
resolution image with the best performance possible. Raw images are dark subtracted,
gain-normalized, and processed in hardware to detect individual electrons with sub-pixel
accuracy giving a 4x as many pixels in each image.
figure 1-13. K2 Direct Detection palette: Super-Resolution mode
Updating Reference Images
NOTE:
Power cycling the hardware does not maintain the stored hardware background
reference and hardware gain reference used for Counted and Super-Resolution
modes. You must re-upload your references images before starting data
collection.
Reference must be re-acquired or uploaded from a saved image on disk after power cycling.
DigitalMicrograph detects when this has happened and prompts you to upload or re-acquire
the references.
