Walz MINI-PAM-II, Manual, Page: 64 / 130

Chapter 7 Touchscreen Operation
58
7.2.5 Spectrometer
The SPEC command of the Spectrometer window triggers
reading of data from the spectrometer. In the standard mode, the
spectrometer is equipped with an optical entrance for external
radiation (Fig. 14, page 24). Spectra of photon flux densities are
measured in units of nmol photons m
-2
s
-1
nm
-1
. PAR corre-
sponds to the integral of the spectrum from 400 to 700 nm.
Spectrometer-derived PAR will be used for ETR calculations if
“Use Ext. PAR” in Menu Sensor Settings is checked (available by
selecting “Sensors” in the Main Manu). Additionally, the spec-
trometer must be selected as external PAR sensor (Main Menu

Sensor

Leaf Clip/Ext PAR

External PAR sensor

Spectrometer; Fig. 52, page 89).
Note that the spectrometer measures the PAR of the MINI-PAM-
II internal light correctly only in the CAL mode (Fig. 36, page 67)
because only in the CAL mode the LEDs are operated continu-
ously. In the measuring mode, actinic light is pulse-width modu-
lated and fluctuating PAR is displayed.
To record fluorescence or reflectance spectra, change spec-
trometer configuration as described in Fig. 14 (page 24). Then
select operation mode: Main Menu

Sensor

Spectrometer

Operation Mode.
In menu Operation Mode, the items “Fluores. (blue)”, “Fluores.
(green)” and “Reflectance” set the spectrometer mode to fluores-
cence spectra with blue excitation, fluorescence spectra with
green excitation and reflectance spectra, respectively.
For reflectance measurements, first measure dark current in
complete darkness, then the 100% reflection signal with the