Endress+Hauser OUSAF44, Руководство по эксплуатации

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Product description OUSAF44
8 Hauser
3.2 Measuring principle
Light absorption
The measuring principle is based on the Lambert-Beer law.
There is a linear dependency between the absorption of light and the concentration of the
absorbing substance:
A = -log(T) = ε . c . OPL
T = I/I
0
T ... Transmission
I ... Intensity of received light at detector
I
0
... Intensity of transmitted light of light source
A ... Absorption
ε ... Extinction coefficient
c ... Concentration
OPL ... Optical path length
A light source emits radiation through the medium and the incident radiation is measured on
the detector side.
Once the light has passed through a filter for wavelength selection, the intensity of the light is
determined by a photodiode and converted to a photocurrent.
The subsequent conversion to transmission (%) or absorbance units (AU, OD) is performed in
the associated transmitter.
1 OPL 2 3
4 5 6 8 7 2
A0029412
 2 Absorption measurement with reference
1 Light source
2 Optical windows
3 Measurement filter
4 Measuring detector
5 Lens
6 Medium flow
7 Reference filter
8 Reference detector