Omega Speaker Systems OS550-BB Series User Manual download pdf (Page 65)

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Appendix: How Infrared Thermometry Works

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

= 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

ε = Emissivity

σ = 5.6703 x 10

-8

watts/meter

x K

(Stefan’s constant)

T = temperature of object in Kelvin

= 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.

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Omega Speaker Systems OS550-BB Series User Manual Page 65