LI-COR LI-3100C, Инструкция по эксплуатации

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The LI-3100C now uses the entire 25 cm measurement width for high resolution
(0.1 mm
2
) mode, so it is important to compensate for the above-mentioned edge
effect for the calibration procedure. While round discs like those previously used are
simple to manufacture with a precise area, this shape has the least amount of edge
(in this case circumference) compared to its area.
As a result, large changes could be made to the calibration adjustment with little
effect on the resulting readout. A large adjustment that makes the average reading
appear closer to the area of the round disc could now increase the errors in samples
with a high ratio of edge to area.
To address this issue, LI-COR is providing a new 10 cm
2
calibration plate with a
higher edge to area ratio. The user will find that the calibration adjustment is very
sensitive to small changes with this new calibration standard. This “edge-intensive”
standard is run through the area meter in a number of positions along the meas-
urement width, after which the round calibration discs are run through in a similar
fashion; the round discs should still produce results within the basic accuracy spe-
cifications. Thus, the user can view the response of the instrument to the different
extremes of sample geometry, and is assured of a better calibration. In addition, for
exacting measurements, the user can see which area of the measurement zone yields
the highest precision and accuracy.
Calibration procedure
1 Start the lamp and allow it to warm up for 5 minutes or more. Make sure that the camera position
and lens settings match the marks indicated for 0.1 mm
2
resolution (see Changing measurement
resolution on page 4-1). If transparent belt flaws, or debris on the belt is causing spurious counts
on the display, you may need to clean or replace the belt, as necessary.
2 Run the edge-intensive standard through the area meter at least 10 times, and average the read-
ings. Repeat over all of the areas of the sample width area. For example, use 5 zones from front to
back, and repeat to total 10 readings. If the error exceeds 2%, carefully turn the CAL screw a small
amount, clockwise to increase, or counterclockwise to decrease. Avoid changing the adjustment
too much. It is better to perform several trials, as normal sampling statistics will cause each trial to
vary slightly.
3 As a confirmation, perform the same 10 measurements with the 10 cm
2
round calibration disc. The
errors should remain within the specified limits. It is not necessary to turn the CAL screw until the
errors are zero; turning the screw more than a few degrees can actually increase errors in meas-
urement accuracy.
Section 3. Operation
3-3 Calibration procedure