Download PM-IRRAS Accessory - Agilent Technologies

Basic Operation
In step scan mode, the IR radiation is phase modulated by the
interferometer, typically at phase modulation frequencies of 400 or
800 Hz at an amplitude of 1.0 or 2.0 λHeNe, and stepping at
0.5–2.5 Hz. The modulated radiation follows the same optical path as
in the rapid scan measurement described above. In step scan mode
the optical low pass filters have dual purpose. In addition to enabling
higher throughput at frequencies of interest, a major advantage is a
reduction in collection time. Although the optical arrangement is
identical between step and rapid scan, there is a significant
difference in the way that the detector signal is processed. In step
scan mode, unique digital signal processing (DSP) software within
Resolutions Pro is used to replace the function of the LIA, the
electronic filters and the second A/D converter.
Data collection
Data can be collected either in rapid scan mode or in step scan mode,
which uses DSP(3) software. See the DSP(3) section in the Help.
Preparing the PEM-IRRAS
Power
The PEM controller should be plugged into an AC (alternating
current) outlet. For power requirements refer to the PEM-100 User
Manual.
Power for the detector is supplied from the FTIR spectrometer.
Detector cooling
Fill the detector Dewar with liquid nitrogen for each detector to be
used, as described on Page 15.
PM-IRRAS Accessory Hardware Manual
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