Metrohm NIRS XDS Interactance OptiProbe Analyzer - Manual (Page 65)

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Vision requests “Position Reference”.
The OptiProbe should be placed in the top
opening, gently resting against the Spectralon
instrument reference.
This shows the correct Reference position for
the XDS OptiProbe.
(Do not press hard, as this may change the
reflectivity of the material.)
NOTE: The instrument reference is
Spectralon®, which is a PTFE material. This
instrument is designed for use with raw
powders, with no sample window. The
Spectralon does not have a quartz window
over it, because a window would change the
reflectivity. Therefore it is very important not
to allow dirt to contact the reference.
If operating in Reference Standardized mode,
Vision requests the 99% standard from the
set.
(If not operating in Reference Standardized
mode, Vision requests the 80% standard,
which is used in place of the internal
instrument reference.)
Select the requested standard from the set. Labels on
the back of each standard identify the reflectance
value. Place in drawer (note rotational position) and
close drawer fully.
Move the OptiProbe from the top opening (reference)
to the middle opening. Gently lower it to contact the
standard. Do not push on the glass, as this may
scratch the quartz window.
The standards used for this test are R99, R40, R20,
R10, and R02.