Metrohm NIRS XDS Process Analyzer – DirectLight/NonContact - Manual (Page 109)

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The spectrum shown above does not exhibit any noise effect from fiber attenuation. Actual fiber
optic probe spectra will exhibit noise at the lower and upper ends of the spectrum, based upon
length of fiber used. This is normal.
A Wavelength Linearization is performed in the forward direction of grating scan, then again in the
return direction. The resulting information is adjusted by Vision into one corrected spectrum.
These peak positions are not meant to be traceable, as the wavelength calibration of the instrument
is done on an external standard, traceable to NIST.
The internal wavelength materials are used to maintain the external wavelength registration by use of
software adjustment for any external effects on the instrument.
Select Wavelength Linearization from the
Diagnostics menu. The instrument will scan the
reference, which is the fiber optic that runs from
the monochromator to the detector area inside the
instrument.
Peak positions for the reference materials are located using a peak-finding algorithm. These “found”
peaks are compared to the nominals. This is done twice, one for each direction of the grating
motion. Follow instructions on screen.
After the linearization is successfully sent to the
instrument, this message confirms the transfer.
Click “OK” to proceed.