LI-COR LI-3100C, Инструкция по эксплуатации

Страница: 16 / 50

Section 3. Operation
Belt tension and tracking adjustment
Belt tracking is adjusted by moving the sliding pulley bearing blocks ( Figure 2-2 on
page 2-3). The belts likely will not maintain alignment without some adjustment. If
a belt progresses toward one end of a pulley, then tighten that side of the belt. Fine
adjustments are performed by twisting the block adjustment screw to push the slid-
ing bearing block. The knurled knobs located on the pulley bearing blocks must be
loosened to allow block movement.
Calibration
General guidelines on the need to calibrate follow.
l
After installing a new lamp (let it run for several hours first).
l
After replacing extremely worn or cloudy belts.
l
When a large change in ambient operating temperature occurs.
l
As a result of obvious misadjustment.
Caution: Improper adjustment can seriously decrease the accuracy of finely
detailed samples.
Some history
Two calibration discs were included with LI-3100 Area Meters so that users could
make minor adjustments of area readout, using the CAL screw on the instrument
front panel. The smaller disc was used with the high resolution option, as the larger
disc would not fit between the 7.5 cm sample guides used for 0.1 mm
2
resolution.
The calibration method involved repeatedly measuring the appropriate disc until the
average error was less than 0.5 percent for high resolution, or 1 percent for low res-
olution.
Due to the optical characteristics of the lamp and lens, the discs read higher in the
center of the measurement zone than nearer the sample guides, when the LI-3100
was configured for low resolution (1 mm
2
). However, samples that have a very high
ratio of edge to area (i.e., conifer needles, small irregular leaves, roots, etc.) exhibited
the opposite effect. In addition, incorrect calibration resulted in larger errors with
these samples.
3-2 LI-3100C Area Meter Manual