Photometrics Evolve 512, User Manual

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20 Evolve 512 Users Manual
Rapid-Cal
Calibration
The Evolve 512 has incorporated a calibration routine which allows the camera to adjust
voltages of the ADC offsets such that the electron multiplication gain input given to the
camera reflects the actual gain provided by the device. Settings 1 to 1000 on the electron
multiplication gain slider are mapped linearly to provide the actual multiplication gain
requested by the user. Due to the impact-ionization method used with the electron-
multiplication gain register the actual gain realized by the detector with time will slowly be
reduced. By using the calibration routine the camera is able to re-establish the electron
multiplication gain slider such that it will provide the gain which is input on the gain slider.
This ensures the quantitative nature of the camera over time. Even though the camera is
capable of delivering large multiplication gain factors, multiplication gain should only be
used as needed to preserve as much dynamic range as necessary and to prolong the device’s
lifetime.
Figure 16. DAC Setting vs. Charge Multiplication Gain for Evolve 512
EMCCD cameras are subject to aging of the EMCCD register as a result of its usage. The
Evolve 512 has a simple calibration feature that performs the industry’s most accurate EM
calibration within 3 minutes. A simple turn of the cameras nose-piece closes a shutter and
activates a light source which the detector uses to calibrate its EM gain. This ensures that
users will receive the most accurate electron multiplication and the EM gain applied
matches what the user requests. Simple software control will allow the user to use this
feature as a manual shutter in order to block all light from the sensor in order to take dark
reference frames if necessary.
How will Rapid-Cal help?
It is a necessary requirement that your electron multiplication be accurate if you wish to be
quantify the images taken by an EMCCD camera. The evolve cameras Rapid-Cal allows
extremely accurate and rapid calibration of the EM-Gain ensuring your data can be
quantitative all of the time. It is recommended that calibration be performed once a week
although the requirements of calibration will vary depending on the usage of the camera.