Principles behind the TIR100

Measuring principle

The sample is subject to thermal radiation at a temperature of 100°C. A black body half-sphere radiator is used to capsulate the sample to ensure homogenous illumination. The reflected infrared radiation is observed at an angle and is converted into a numeric value. This value is then plotted against a calibration table from high and low emissivity reference standards.
All of this is accomplished at a touch of a button when using the TIR.

Specifications of the TIR100-2

Voltage range	90 VAC – 260 VAC
Power rating	240 VAC max. 130 W 120 VAC max. 260 W
Measuring range	As Calibration Standards
Measure Uncertainty	+- 0,005 (lowE) … +-0,01 (hiE)
Spectral range	2,5 – 40µm
λmax of radiant energy	7,8 µm
Radiator temperature	100°C
Measuring Duration	approx. 5 sec.
Measuring spot	approx. 5mm
Interface	USB-B
Dimension	230mm x 140mm x 120mm
Weight	TIR100-2: approx. 2,0kg

Some basic physics principles

Stefan Boltzmann‘s law

The following physic principles are used to determine the emissivity from a black body radiator.
Every body with a temperature above absolute zero radiates thermal heat. The quantity of heat (power) is given by

P= σ * ε * T4
P = RadiativePower [W/㎡]
T=Temperature[K]
ε = Emissivity
σ = Planck’s Constant [W/K4㎡]

Emissivity ε is the degree of radiative energy compared to that of an ideal blackbody:
ε = 0 .. 1

WIEN’S DISPLACEMENT LAW

Wien’s displacement law states that the wavelength distribution of radiated heat energy from a black body at any temperature has essentially the same shape as the distribution at any other temperature, except that each wavelength is displaced, or moved over, on the graph.

The wavelength of maximum radiative energy could be calculated by