Metrohm NIRS XDS Process Analyzer – DirectLight/NonContact - Manual (Page 105)

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The Master Instrument was first calibrated using SRM-2035, and the resulting peak positions of the
WST3Wxxx standard were determined. Each calibration standard is verified for correct response prior
to shipment. The correlation of the calibration standard to SRM-2035 is checked on a regular basis to
assure consistent response.
The XDS instrument is set to predetermined nominals during Instrument
Calibration, since these are the best-known information for NIR peak wavelengths.
In Wavelength Certification, the NIST-stated
uncertainty of 1.0nm is applied.
11.5.4 Window Correction, Transmission Probes
Window Correction is a method to permit the user to calibrate the fiber optics using a calibration
fixture. Next, the fibers are inserted into the barrels, and the optical differences are mapped. This
gives a clear, repeatable measure of the optical difference between the two geometries.
This window correction method offers a large advantage to users running with probe barrels
permanently installed in a reactor or other vessel. At initial set-up, the window difference is measured
and stored in Vision.
At periodic maintenance intervals, the fiber optic
bundles can be removed from the barrels, which
are now permanently installed.
The instrument and fiber optics can be calibrated for wavelength and Reference Standardized
response, without using the Transmission Probe barrels. After this is done, the fiber optic bundles are
put back into the permanently installed barrels, and the Window Correction is re-applied. This assures
consistent response, without removing the barrels.
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.
Be sure the fiber probe ends are securely installed into the barrels (outer probe part) and proceed
using this set of instructions.