SHB_U14 Chapter 3: Module components 3-11
Filter cell
Location in module
The filter cell is installed between the sample cell and infrared detector or between
the sample cell and calibration cell.
Structure
The filter cell consists of a gold-plated tube.
A land divides the cell into a sample chamber and a reference chamber; there is a
gas link between the two.
The filter cell sealed with infrared-transparent windows on both sides.
Two positioning pins secure the filter cell in the beam path.
Function
The sample and reference sides are individually filled with the applicable
interference gas.
This causes absorption of the portion of the beam in the range of the interference
gas absorption lines.
Result: A sharp reduction in cross sensitivity.
Versions
For various applications there are various versions of the filter cell, as shown
below:
Nominal length
NL
mm
Surface Fill Part number
Gold plated
Figure 3-13
Filter cell
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