Metrohm NIRS XDS MasterLab Analyzer - Manual (Page 35)

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These dimensions are the center of each vial
opening in the tray. Vision uses these
coordinates to position each vial during
sampling.
Note that there are other important
dimensions, including the vial “support ledge”,
and the flatness of the final tray. Because the
fabrication is critical to repeatability, Metrohm
NIRSystems does not recommend local
machining.
Please contact your Metrohm NIRSystems
Distributor for ordering information.
You will need to supply both screens shown, as
the final tray will be machined to these
specifications.
A charge applies for each custom tray supplied.
5.3 Spot Size Adjustment
The MasterLab Analyzer offers spot size adjustment for reflectance use. This feature permits the user
to set the relative size of the illumination beam that strikes the sample. This is useful for small objects
such as 15mm vials (about 5ml volume), and other small-diameter materials, operating in reflectance.
NOTE: When selecting the transmission detector (for tablets) the spot size defaults to 9.5mm.
The instrument energy is focused into a smaller area, providing better intensity within the area of
interest. This provides improved signal-to-noise on tablets. Do not change this setting in transmission.
In the Data Collection Method (DCM) shown below, the spot size is entered as 12mm, for a 15mm
vial, operating in reflectance.
The spot size (set in the Data Collection Method) should be no larger than 80% of the vial diameter.
For each default vial size in the Select Tray Dialog box, set spot size as follows:
• 15mm vial: 12mm spot size
• 19mm vial: 15mm spot size
• 25mm vial: 17.5mm spot size
• 29mm vial: 17.5mm spot size
As a rule, a large spot size is preferable for large samples. This provides as much sample viewing area
as possible for a good cross-sectional area of the sample. The default spot size is 17.25mm.