MikroScan 7600PRO, Руководство оператора

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Section 8
280
MikroScan 7600PRO
Operator’s Manual
Catalog 11180-94
V15.4F 050406
Principle of Thermal Imaging
8.5 Determining Emissivity
Emssvty s the rato of energy radated from an object to the exteror and energy rad-
ated from a blackbody. The emssvty vares wth the surface condton of the object
and also with temperature and wavelength. If this value is not accurate, then the true
temperature cannot be measured. In other words, a variation or change in emissivity will
cause a change n the ndcatons on a thermal mager.
To approach the true temperature therefore,
Therefore, in order to perform correct measurement for true temperature, the emissivity
is determined as follows:
1) By means of a printed table
Various books and literature carry physical constants tables, but
if the measuring condition is not identical, the constants may
not usable. In such cases the lterature should be used only for
reference.
2) Determination by ratio — Option 1
A contact-type thermometer is used to confirm that the measured
object s n thermal equlbrum and that the blackbody-type
source s at the same temperature. The object and the black-
body-type source are then measured wth the radaton ther-
mometer and the resulting energy ratio is then used to define the
emissivity as follows:
EK : ES = 1 : X
Where,
3) Determination by ratio — Option 2
An object, resembling a blackbody, is attached to a heat source
to make the temperature of the blackbody part and the measur-
ng object the same. The rato of nfrared radaton energes are
then determned as n #2 above.
The emssvty must approxmate 1.0 ( The measured object must be
nearly a blackbody.)
The emssvty must be corrected. ( The emssvty of the measured
object must be nternally corrected to 1 by the thermal mager.)
EK : energy of blackbody-type source
ES: energy of measured object
X: emissivity of measured object