Metrohm NIRS XDS SmartProbe Analyzer - Manual (Page 49)

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Vision continues.
No operator action is required at this point – this
screen is for information only.
Once Vision has finished with this screen, a result
screen will be displayed.
A typical result
screen is shown.
Peak positions for
the reference
materials are
located using a
peak-finding
algorithm. These
“found” peaks are
compared to the
nominals.
Differences should
be no more than
0.4nm for any peak.
Click “Yes” to send the linearization to the instrument.
After the linearization is successfully sent to the
instrument, this message confirms the transfer.
Click “OK” to proceed.
This procedure is done twice, once for each direction of the grating motion. Repeat steps as
prompted by Vision.
7.1.2 Reference Standardization
Reference Standardization is a method to provide a virtual 100% reflectance reference at each data
point, to serve as a true spectroscopic reference with no character attributable to the physical
reference used. This is important to achieve a high-quality spectrum on each instrument, and to
enhance transferability between instruments.
A photometric standard of known reflectivity (as measured on an absolute reflectance scale) is
scanned on the instrument. The instrument Spectralon® standard, located in the upper opening, is
scanned. The differences of the instrument standard from 100% reflectivity are mapped, and a
photometric correction is generated. This correction is then applied to every spectrum taken on the
instrument, to make each spectrum appear as if taken with a reference of 100% reflectance. This
assures that bright samples do not saturate the instrument, or produce negative absorbance values.
Vision software stores the Reflectance Standard file, which is downloaded to the instrument, and is