The SPEC detector shows persistence on
exposures as low as 500 total data numbers (DN)
Saturation = 33,000 DN
Persistence is localized residual charge on a detector due to
exposing that detector to light. For IR detectors that clock
continously and have no shutter, persistence can occur simply
by pointing a bright light source—even without taking an
exposure. Persistence is tricky: its effects can be seen on
a hard stretch even if there is no effect on the overall noise
of the detector.
Case 1: Low exposure level
| Source |
AO Frame Rate (Hz) |
AO WFS counts |
Approx Rmag |
| AO fiber |
438 |
1000 |
10 |
| Image |
Filter |
Scale (mas) |
Exp. Time (s) |
Elapsed Time (min) |
Peak Exposure (DN) |
Ratio to Peak |
| s110819_a001005 |
Kn3 |
20 |
2 |
0 |
500 |
1 |
| s110819_a002001 |
Drk |
20 |
600 |
13 |
15 |
3.0e-02 |
| s110819_a002002 |
Drk |
20 |
600 |
23 |
4 |
8.0e-03 |
| s110819_a002003 |
Drk |
20 |
600 |
34 |
... |
... |
| Histogram Equalization Stretch |
x column: 1276, y rows: 751-950 |
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