Metrohm NIRS XDS Process Analyzer – DirectLight/NonContact - Manual (Page 69)

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11.1.3 Instrument Calibration, Interactance Reflectance
First select the channel. From the menu bar, click
on Acquire, then Select Channel. Use the spinner
to select the correct channel, then click on “OK”.
This must be performed for each channel. Always
verify the channel before proceeding with the test.
Instrument Calibration uses a traceable, stable,
standard, of known wavelength response, as a
method to establish wavelength scale response of
the instrument.
The instrument is set to scan the standard, and the
nominal peak positions for each major absorption
are determined. Vision performs an algorithm to
set the peak positions of the instrument to those
of the standard. These adjustments are saved, and
are applied on each subsequent scan of the
instrument, yielding a correct spectrum.
This adjustment is performed in Interactance
Reflectance, and applies to both Interactance
Reflectance and Interactance Immersion.
Vision takes an instrument reference, using the
internal reference fiber. This takes about 60
seconds.
This photo shows the internal reference fiber,
looping gently from the lamp box to the entrance
slit of the monochromator. (Sample fibers are
omitted for clarity.)