CFM Operation
CIRAS-2 Operator's Manual Version 2.04
- 106 -
Enable Modulating Beam
For fluorescence measurements, “Enable Modulating Beam” must be selected for meaningful results. We
recommend starting with the default Mod. Level of 3 and an initial gain of 50 to try and achieve an average
fluorescence signal (Fa) in the range of 700-800 A/D counts.
Mod. Level
This controls the number of samples that are averaged to give the fluorescence signal. There is one
modulation pulse per sample and it is 1.5 µs duration.
Important note. Prior to placing the leaf sample in the cuvette, allow the CIRAS to complete both the
LED and CFM tuning process. When you are into the program and the main CIRAS display is shown,
place your leaf sample in the cuvette and close it. You want to see a steady fluorescence signal similar to
this before proceeding with fluorescence measurements:
If the signal is too high, lower the gain and/or lower the modulation level accordingly. If the signal is too
low, increase the gain and/or increase the modulation level to 4 and adjust the gain until you achieve the
desired fluorescence signal in the 700-800 range.
Gain
The gain controls the amplification of the sensor signal. The CFM uses a 12-bit A/D converter so that for
maximum resolution, the gain should be adjusted so that the maximum fluorescence signal (Fm) is
approaching the maximum possible A/D value (4096 units). The user must establish the optimum gain
needed for the species measured. Once established, there should be no need to change the gain for
individual leaves.
Perform CFM Tuning
Manually begin a CFM tuning – only needed if prompted by CIRAS-2 to do so.
To Next Page
Loading...
Need help?
General
