Metrohm NIRS XDS Process Analyzer – DirectLight/NonContact - Manual (Page 84)

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In Instrument Calibration, the XDS instrument is set to nominals which provide excellent instrument
transfer, and which meet published NIST wavelengths when tested in Wavelength Certification. Peaks
for the additional ingredient are set to peak nominals determined by measurement on several
different types of research instrumentation.
In Wavelength Certification, the NIST-stated uncertainty of 1.0nm is applied. Tighter tolerances are
not appropriate, unless NIST revises the stated uncertainty of SRM-1920a at some point in the future.
11.2.4 Window Correction, Interactance Immersion
Window Correction is a method to permit the user to calibrate the fiber optics using an Interactance
Reflectance Probe, then insert the fiber into the Interactance Immersion Probe, and map the optical
difference in response between the two geometries.
This window correction method offers a large
advantage to users running with a probe barrel
permanently installed in a reactor or other vessel.
At initial set-up, the window difference is
measured and stored in the instrument by channel.
At periodic maintenance intervals, the fiber optic
bundle can be removed from the barrel, which is
now permanently installed.
The instrument and fiber optic bundle can be calibrated for wavelength and Reference Standardized
response, without using the Interactance Immersion barrel. After this is done, the fiber optic bundle is
put back into the permanently installed barrel, and the Window Correction is re-applied. This assures
consistent response, without removing the barrel.
The instrument and fiber optics can be calibrated for wavelength and Reference Standardized
response, without using the Interactance Immersion Probe barrel. The Interactance Reflectance probe
barrel is used instead. After this is done, the fiber optic bundle is put back into the permanently
installed Interactance Immersion barrel, and the Window Correction is re-applied. This assures
consistent response, without removing the barrel from the process.
Because the spectroscopic response of various fibers is dependent upon length and other factors,
screens will not be shown. Instead, the message boxes are given, in the order in which they appear.