Operating Principle - Siemens LDS 6 Operating Instructions Manual

2.3

Operating Principle

LDS 6 is a gas analyzer employing single-line molecular absorption spectroscopy. A diode
laser emits a beam of near-infrared light, which passes through the process gas and is
detected by a receiver unit. The wavelength of the laser diode output is tuned to a gas-
specific absorption line. The laser continuously scans this single absorption line with a very
high spectral resolution.
The result is a fully resolved single molecular line which is analyzed in terms of absorption
strength and line shape. The influence of cross-sensitivities on the measurement is
negligible, since the quasi-monochromatic laser light is absorbed very selectively by only one
specific molecular line in the scanned spectral range.
Figure 2-6 Basic design of the LDS 6
LDS 6
Operating Instructions, 01/2009, A5E00295894-05
Technical Information
2.3 Operating Principle
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