Teledyne ProEM Series, System Manual

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Chapter 5 Operation 71
Even though the camera is capable of delivering large multiplication gain factors, EM
gain should be used only as needed to preserve as much dynamic range as possible.
NOTE:
As the on-chip multiplication introduces additional noise
and reduced effective dynamic range, it is recommended
that the multiplication be used only as required. Typically,
only 100x or lower EM gain is required to achieve <1 e
-
rms
effective read noise. Using higher EM gain does not improve
signal-to-noise ratio, but it can accelerate sensor EM gain
aging while lowering effective dynamic range. For more
information, refer to the On-Chip Multiplication Gain
technical note. This technical note can be accessed by
going to the Teledyne Princeton Instruments web site at
www.princetoninstruments.com
and searching for that
title.
5.3.3 EM Gain Calibration
NOTE:
EM Gain Calibration is not currently available in LightField.
Each ProEM camera is factory-calibrated for linearized EM Gain. Over time, however,
aging of the EMCCD array may degrade gain linearity. Because aging appears to be a
strong function of the amount of charge that flows through the multiplication register,
users who consistently operate the camera at high gain at high light levels may need to
recalibrate EM gain more frequently than those who are looking at lower light levels at
lower gain.
To compensate for aging, each ProEM contains a built-in shutter and light source that
allow you to perform an on-demand EM Gain Calibration. Once the EM gain calibration
has been performed, the gain value you enter in the software will be the actual
multiplication gain applied to the input signal.
To Perform EM Gain Calibration in WinX/32:
1. Locate the
EMGainCalib.exe
program (located in the application program
directory.
2. Make sure the ProEM camera system is running.
3. Exit the application program (WinView/32 or WinSpec/32).
4. Launch the
EMGainCalib.exe
program.
5. Upon initiation of the calibration, the built-in shutter closes, the built-in light source
illuminates the array, a succession of data frames are acquired, and the calibration
map is calculated. A progress indicator is displayed during the calibration.
6. Wait until the calibration (it might take 10 minutes or longer) has been completed
before restarting the application program.
CAUTION!
!
Do not operate the camera while EM gain calibration is in
process.