Metrohm NIRS XDS Process Analyzer – DirectLight/NonContact - Manual (Page 98)

96 ▪▪▪▪▪▪▪
The first test to be run is Wavelength Linearization. This provides initial wavelength locations for the
sample spectrum, prior to final wavelength calibration.
Wavelength Linearization uses internal wavelength materials to determine a set of internal, arbitrary
peak positions that the instrument will use to maintain repeatability of wavelength response.
Wavelength Linearization is performed on the internal reference fiber located in the XDS Process
enclosure.
The wavelength positions of these peaks appear as shown.
The scale of this display is marked in encoder pulses, which do not relate to nanometers directly.
From the peaks, a linearization is performed, which allows assignment of nanometer values. (Actual
spectral shape depends on fiber configuration.)
The spectrum shown above does not exhibit any noise effect from fiber attenuation.
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.