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When adjusting the modulated light for momentary dark adaptation
, the modulated
light is set correctly, if it is set high enough to get a reading when the measuring button is
pressed. The setting is linear.
The “Gain” should be as low as possible for the best signal
to noise ratio.
When adjusting the modulated light for longer dark adaptation,
use the following
procedure. Put a leaf, of the type to be measured in a study, in a dark clip, and dark adapt.
Place the fiber optic probe all the way into the dark clip, and expose the dark adapted area of
the leaf to the modulated light. The modulated light is always coming out of the end of the
fiber bundle when a measuring screen is viewed. The modulated light is set correctly if it is
high enough to get a fluorescence measurement when the measuring button is pressed, but
not too high so that it is driving photosynthesis. A setting that is too high will give an
incorrect reading of Fo, a value that should be a pre-photosynthetic measurement. The setting
is linear. The “Gain” should be as low as possible for the best signal to noise ratio.
New -automated modulation light set up
“
Auto Gain
” – On the set up screen. This option automatically adjusts the modulated
light setting to a detection range that will work for the sample. Press “Auto Gain” and the
instrument automatically goes through a routine that sets the modulation intensity
correctly. A leaf must be in the PAR Clip, open body clip, or dark clip when this routine
is running.
Yield Test Setup Screen
Setting the saturation pulse intensity
Values can be set from 5% to 100% in 5% increments. At 100%, the intensity of the
saturation pulse is approximately 11,000 umols when used with a dark clip. Saturation
intensity is approximately 6,200 umols when used with a PAR Clip or open body clip.
To use the automated modulation light setup mode, press
“Auto Gain”. The system then adjusts the modulation light
source into an acceptable minimum reading range for the
PIN diode detector.
