Metrohm NIRS XDS Process Analyzer – DirectLight/NonContact - Manual (Page 11)

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1.2 Fiber Optic Probe Ends
The Interactance Reflectance Probe is used for processes where the medium is somewhat turbid and
will provide a good reflectance signal back to the instrument. This includes fermentation products
and other materials with high solids content.
The fiber optic bundle has two channels. One carries the
light to the probe, and the other channel carries the
reflected signal back to the detector for analysis. This
probe requires only one pressure port in a reactor.
The fiber bundle, showing the concentric channels, is
shown at right. This is a “Micro-Bundle” type, which has
40 fibers per set.
Transmission Probes are used for liquids that may be clear to somewhat turbid. Work may be
required to determine the optimum pathlength, based upon the sample medium, and the analyte
level.
This photo shows threaded transmission probes, which
come with several spacers (2mm shown) which maintain
the probes at a pre-determined distance for consistent
analysis. Use 1” Swagelok® fittings.
Customers may have designed their own interface to the process, and prefer transmission probes as
shown.
These may be placed into the process using 1” Swagelok® fittings. A method of gapping the ends
must be found, to assure consistent position.