Wien’s Displacement Law describes the exact mathematical
relationship between the temperature of a blackbody and the
wavelength of the maximum intensity radiation.
where
λ
m
= wavelength measured in microns
T = temperature in Kelvin
Calculating Temperature
The net thermal power radiated by an object has been shown to
depend on its emissivity, its temperature and that of the ambient
temperature around the object. A very useful equation known today
as the Stefan-Boltzmann Law has been shown both theoretically and
empirically to describe the relationship.
I = thermal power in watts/meter
2
ε
= Emissivity
σ
= 5.6703 x 10
-8
watts/meter
2
x K
4
(Stefan’s constant)
T = temperature of object in Kelvin
T
a
= temperature of ambient surroundings in Kelvin
The infrared thermometer uses this equation directly in calculating
the temperature of an object. The incident power is measured by the
infrared detector. The emissivity of the object is determined by the
user. The ambient temperature is measured by a sensor inside the
thermometer. With all quantities known, the thermometer uses the
Stefan-Bolzmann Law to calculate and output the temperature of the
object
A-3
Appendix: How Infrared Thermometry Works
A
Summary of Contents for OS550A
Page 4: ...ii OS550A Series Industrial Infrared Thermometer This page is intentionally blank ...
Page 9: ...vii TABLE OF CONTENTS This page is intentionally blank ...
Page 21: ...Installing the Infrared Thermometer 2 2 8 Notes ...
Page 46: ...3 25 Using the Infrared Thermometer Transmitter 3 Notes ...
Page 47: ...Using the Infrared Thermometer Transmitter 3 3 26 Notes ...
Page 51: ...Laser Sight Accessory 4 4 4 Notes ...
Page 53: ...Maintenance 5 5 2 Notes ...
Page 57: ...Troubleshooting Guide 6 6 4 Notes ...
Page 63: ...1 8 2 Notes Glossary of Key Strokes 8 ...
Page 75: ...I 3 Notes ...