CIRAS-3 Operation Manual V. 1.09
135
Fv/Fm
. If selected, you must allow the leaf to dark adapt prior to making the
measurement. Enter the time (in minutes) at “
Concluding Dark Adapt
Period
” and we recommend dark adapting the leaf for at least 20-30 minutes
for best results.
Modulating Light
Gain
. Used to adjust the resolution of the fluorescence signal. We
recommend that the gain be set to a % that achieves a steady F
o
value
between 400-700.
Modulation Level
. Modulation Level (1-4) determines the frequency of
sample fluorescence counts. Higher levels have better signal to noise, while
lower levels have poor signal to noise but have no actinic effect. For example,
greater noise due to a lower modulating frequency can have a large effect on
measuring the lowest two values used to arrive at an average of Fo’ under far-
red light.
Saturating Light
Single Pulse Measurements
Single Pulse Duration
. The time (in seconds) for the Single Pulse Duration
saturating light to be applied.
Single Pulse Intensity
. The saturation pulse intensity (0-10000 µmol m
-2
s
-1
).
Multi-Pulse Measurements
Multi-Pulse Duration
. The time (in seconds) for each multiple pulse duration
saturating light to be applied. For Multi-Pulse measurements, you have up to 5
steps but you must set at least 3 steps. Based on our testing, we recommend
at least one step above 3000 µmol m
-2
s
-1
at
the high end and one step below
1500 µmol m
-2
s
-1
at the lower
end with an even distribution of light in between
the high and low light settings.
Press
Accept (F2)
to accept changes and return to the main Settings dialog.
CFM-3 Controls
There will typically be very little need to change Settings during the active session while measuring
chlorophyll fluorescence. However, some active controls and functions are available for sample
calibration and to make slight adjustments prior to or during measurements. At either the Numeric View
or Graph View screens select
Controls
(F3)
>
CFM Control (F7)
. The following selections are available:
