Metrohm NIRS XDS Process Analyzer – DirectLight/NonContact - Manual (Page 100)

98 ▪▪▪▪▪▪▪
11.5.2 Reference Standardization, Transmission Probes
Reference Standardization with Transmission Probes uses an innovative means to adjust each channel
to a repeatable, transferable level of spectroscopic response. The fiber ends are placed into a fixture,
the response is measured, and the signal is “normalized” using a spectral correction.
This shows the fixture. When Reference Standardizing, this fixture holds the two probes in alignment,
at a pre-determined distance.
The optical response of the air gap is measured and stored. A correction is applied, to bring the
channel to “0 Absorbance” in transmission, corresponding to the response of an air reference.
This fixture is also used in Instrument Calibration.
Follow these instructions to perform Reference Standardization:
1. Insert each probe into the fixture as
shown.
2. Tighten the thumbscrew gently on the
probe.
3. With both probes in position, cover the
center area shown in the photo to prevent
stray light from affecting the Reference
Standardization.
Do not insert the WST3Wxxx standard.
Nothing is to be placed between the fiber
bundle ends during Reference
Standardization.