Pyrometer- Handbook - Contika
Pyrometer- Handbook - Contika
Pyrometer- Handbook - Contika
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6.2 Atmospheric Windows<br />
The atmosphere is normally the medium through which<br />
radiation must pass to reach the pyrometer. Quality<br />
pyrometers have been built with spectral ranges which will<br />
not allow measurements to be influenced by the<br />
atmosphere. These areas are called atmospheric windows.<br />
In these windows there are no absorption bands of water<br />
vapour and carbon dioxide in the air, so that measuring<br />
errors due to moisture in the air or due to a change in<br />
measuring distance are eliminated.<br />
Illustration 13 shows where the atmospheric window is<br />
located within the spectrum in comparison to the<br />
transmission of air and its dependency on wavelength.<br />
Transmission in %<br />
<strong>Pyrometer</strong> <strong>Handbook</strong><br />
Transmission of air<br />
window type of detector/material<br />
1 Silicon (Si)<br />
2 Germanium (Ge)<br />
Indium-Gallium-Arsenide (InGaAs)<br />
3 Lead Sulphide (PbS)<br />
4 Lead Selenide (PbSe)<br />
Thermopile<br />
Pyroelectric Detector<br />
5 Thermopile<br />
Pyroelectric Detector<br />
6 Thermopile<br />
Pyroelectric Detector<br />
Wavelength in µm<br />
no absorption<br />
Illustration 13:<br />
atmospheric<br />
windows<br />
and<br />
transmission<br />
of air<br />
27
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