LI-COR LI7200RS, Instruction Manual

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trates this function by showing the range of responses for a large population of
LI-7200s.
Figure 8-1. The function f(T) characterizes how the raw reference signal varies with tem-
perature.
The C
x
and W
x
values are determined at the factory, but they are not really “factory
parameters”; they will likely change over time, due to source or detector aging, or
even some thin-film contaminant that gets on a window that you just can’t clean
off. Thus, the LI-7200/RS has provisions for you to easily reset
C
x
and W
x
to values
that reflect the reality of your instrument at any point in time. The Calibration but-
ton of the Windows software (see
Signal Strength Tab on page 7-22) opens a window
with a Signal Strength tab. There you will find a button labeled “Reset Signal
Strength” that you can push if you’ve decided your instrument is as clean as you
can reasonably make it, and you want to reset the signal strengths to 100. It does
this by using the current values of
A
wo
and A
co
and performing the following com-
putations:
8-35
8-36
Two signal strength-based values are available from the LI-7200/RS when using the
Windows interface program.
Section 8. Theory of Operation
8-9 CO2 Signal Strength