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IFS 125M User Manual Bruker Optik GmbH
Web Interface 8
i
The nominal value of 15798.0 cm
-1
is equivalent to the wavelength of the HeNe laser of
632.8
nm. The analog signal acquired by the detector is digitized using zero crossings of
the HeNe signal, which ensure equidistant data points (Connes-Advantage of FT-IR
spectroscopy).
ADM (Adjust Mode): This command causes a change of the scanning mode.
There are 6 adjust modes:
•The ADM=0 command (Reinit Scanner) re-initializes the
scanner control like a recovery after a laser error. This
command also terminates all other adjust modes and
returns to laser-controlled scanning, if possible.
•The ADM=1 command (Fast Adjust Mode) causes a rapid
scanner movement between the two light switches without
requiring a proper laser signal. This command is intended
for a rough adjustment of the laser signal over the whole
scanning range. For a fine adjustment of the laser signal,
use the slow adjust mode described below.
•The ADM=2 command (Stop Mode) causes a scanner
stop.
•The ADM=3 command (Slow Adjust Mode) checks the
proper scanner movement. Similar to ADM=1, but with
slower speed.
•The ADM=4 command (Front Short Adjust Mode) com-
mutes the scanner around the front position without
requiring a proper laser signal.
•The ADM=5 command (Back Short Adjust Mode) com-
mutes the scanner around the end position without re-
quiring a proper laser signal.
i If the spectrometer is in an adjust mode unequal to 0, no
measurement is possible.
CPI/CPP (Control
Parameters Integral
and Proportional):
CPI and CPP are the basic scanner control parame-
ters.Their default values are 125. Do not change them
unless there is a scanner control problem. These values
can be optimized for an operation in a vibrational environ
-
ment.
HPF (High Pass Fil-
ter):
This command activates or deactivates the integrated digi-
tal high pass filter at 1.8Hz to eliminate the DC value of the
interferogram. By default, the high pass filter is switched on.
For DC (direct current) measurements, it has to be switched
off.
LWN (Laser Wave-
number):
This value represents the current laser wavenumber. The
nominal value is 15798.0. You can use this command to
change the value manually. Note that this value is automati
-
cally adapted to the particular channel if the channel-spe-
cific wavenumbers feature is activated.
Command Definition
Table 8.13: Direct commands
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