K2 Summit and K2 Base Direct Detection Camera User's Guide
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Updating Summit Hardware Background Reference Image Only
If you wish to update only the hardware background reference image, click the
Update HW
Dark Reference
button on the K2 Direct Detection palette.
Updating Reference Images for K2 Summit Counted and Super-
Resolution Modes
Background reference image (hardware dark subtraction):
1.
Click the
Update HW Dark Reference
button on the K2 Direct Detection palette.
figure 1-31. Update HW Dark Reference button
This operation will create an average of many dark reference images and upload it into the
camera. The whole process takes just a few minutes. It should be done at least once per day.
A fresh hardware dark reference is recommended immediately prior to acquiring a gain
reference. A gain reference taken immediately following a fresh hardware dark reference
will not be invalidated by a subsequent fresh dark reference. This means that regular dark
reference update can save the work of updating the gain reference, which typically takes
longer due to the large exposure factor recommended for minimizing DQE derating from gain
reference shot noise. The addendum provides a diagnostic for ensuring that fixed pattern
noise has not grown too high. When it has, re-running hardware dark reference update will
restore it close to its shot-noise limited level.
Base Gain Reference Collection
Follow the instructions for K2 Base and K2 Summit Linear reference images, above.
Key Points to Ensure Optimum Operation
Counted and Super-Resolution Dose Rate:
Unlike older cameras, for K2 Summit the
DOSE RATE
(instead of total dose) becomes the first concern in getting good images. For
the three Summit modes, the preferred dose rates are shown in the table below.
Summit
Mode
Standard dose
(counts per pixel
per second)
Approximate dose
(electrons per
pixel per second)
Beam
Beam counts
multiplier vs.
counted mode
Linear
5,000–10,000 170
-
340
Bright
30–50x
Counted
8 10
Very dim
1
Super-
Resolution
2 2.5
Very dim
1/4 (counts split
between
quarters of the
sensor pixel)
