Application Note Thermopile Module Analog_r10
Application Note Thermopile Module Analog_r10
Application Note Thermopile Module Analog_r10
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<strong>Application</strong> <strong>Note</strong><br />
<strong>Thermopile</strong> <strong>Module</strong> with <strong>Analog</strong> Outputs<br />
<strong>Application</strong> Hints – Gas Detection<br />
IR lamp<br />
IR Narrow Band<br />
Pass Gas Filter<br />
Gas Molecule<br />
thermopile<br />
detector<br />
Other Molecules<br />
U ∝ I = I ⋅ exp( − kcl<br />
o<br />
)<br />
The gas concentration can be measured by monitoring the absorption of an infrared light beam.<br />
The base equation for gas concentration measurement in the infrared way is Beer’s law :<br />
I=I(0)*exp(-k*c*L)<br />
I<br />
I(0)<br />
k<br />
L<br />
c<br />
Available Infrared<br />
Filter for Gas<br />
Detection<br />
HEIMANN Sensor GmbH<br />
Grenzstr. 22<br />
D-01109 Dresden<br />
Rohrbergstr. 7<br />
D-65343 Eltville<br />
-> radiant flux at the point of measurement<br />
-> base radiant flux of the test system without gas absorption<br />
-> constant (gas and filter specific)<br />
-> measuring distance<br />
-> gas concentration<br />
The radiant flux is proportional to the output voltage of the sensor module : U/U(0) ~ I/I(0) .<br />
A special infrared light source is used to generate the radiant heat. The infrared source needs to<br />
be pulsed to eliminate parasitic temperature influences.<br />
The temperature reference output (housing temperature) of the sensor module can be used to<br />
compensate ambient temperature drift effects.<br />
Transmission in %<br />
100<br />
90<br />
80<br />
70<br />
60<br />
50<br />
40<br />
30<br />
20<br />
10<br />
0<br />
G5<br />
HC<br />
G5.1<br />
HC<br />
Managing Director<br />
Dr. J. Schieferdecker<br />
Reg. at District Court<br />
Dresden HRB20692<br />
VAT-ID DE813444739<br />
G20<br />
Ref.<br />
G2<br />
CO 2<br />
G1<br />
CO<br />
G4<br />
NO<br />
3.5 4.0 4.5 5.0 5.5<br />
W avelength in µm<br />
Internet: www.heimannsensor.com<br />
Mail: info@heimannsensor.com<br />
Phone 49 (0) 6123 60 50 30<br />
Fax 49 (0) 6123 60 50 39<br />
<strong>Application</strong> <strong>Note</strong> <strong>Thermopile</strong> <strong>Module</strong> <strong>Analog</strong> Oct 2011 Page 6 of 7
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