General Tools and Instruments IRT659K - Manual (Page 8)

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By default, the unit enters MAX display mode when powered on. To change the
display mode, you use the MODE/SET button to cycle through a seven-step
sequence comprising the four display
modes plus three settable parameters,
as shown in the following figure.
To move from one display mode to the
next mode in the sequence, briefly
press (but do not hold) the MODE/SET
button. As mentioned earlier, you can
change the display mode before or
during a scanning session. Since the
selected display mode (but not its value)
is stored in nonvolatile memory, the
IRT659K will resume operating in that
display mode when it is powered on
following a 30-second Auto Power Off.
ADJUSTING EMISSIVITY AND SETTING TEMPERATURE ALARMS
The IRT659K has three parameters that you can set anywhere over a
predefined range:
1. Emissivity (
ε)—the ability of an object to reflect or absorb IR radiation
(energy)—can be assigned any value between 0.10 and 1.00 in steps of
0.01. The default (factory setting) of
ε is 0.95. Because the IRT659K
measures the amount of infrared energy emitted by a surface, its
measurements are most accurate when they take into account the
characteristic emissivity of the target material.
A perfectly absorbent surface (called a black body) has an emissivity of 1;
it absorbs 100% of the thermal energy hitting it. An object with an
emissivity of 0.8 absorbs 80% of IR energy and reflects 20% of it. All
emissivity values fall between 0 and 1; as a rule, the shinier the surface,
the lower its emissivity.
To maximize the accuracy of IRT659K measurements, you should enter
the actual emissivity of the target surface (see Appendix) using the
instrument’s control panel and the procedure below. Compensating for
emissivity will particularly improve the accuracy of measurements of
surfaces with emissivities nearer to zero than to the default IRT659K
setting of 0.95.