Laser Absorption Spectroscopy
LAS - Laser Absorption Spectroscopy
The highly precise Laser Absorption Spectroscopy (LAS) measurement principle is based on the absorption of specific light wavelengths by the molecules to be detected.
As light source we are using laser diodes at wavelengths from the visible to the mid-infrared range, depending on the gas. By evaluating the intensity of transmitted (I) and incident light (I0) at the detector (Lambert-Beer’s law), the current gas concentration inside the measuring chamber can be determined.
The measured spectrum is compared to the theoretical spectrum based on the HITRAN database, which contains information about the gas absorption lines.
The deviation between both spectra (we call it “Spectral Correlation”) is continuously analyzed and verified. This plausibility-checking mechanism of our LAS sensors guarantees that any kind of abnormality will be detected and the user will be warned.
- Benefits at a glance
- Direct physical measurement
Selective and continuous measurement from the visible to MID-IR spectral range.
Real spectroscopy (no measurement of auxiliary parameters) - No cross sensitivities
The narrow-band tunable laser source ensures highest selectivity for the measured gas. By choosing the ideal absorption lines, other gases have no influence on the measurement - Spectral correlation check
A continuous comparison of measured and theoretical spectrum is done and visualized as “Spectral Correlation”.
It helps the user to see whether his measuring results are plausible or not.
- No condensation, fast response time, low adsorption effects
As the pressure and temperature stabilized measuring chamber is operated in vacuum state, it is (thanks to the correspondingly lowered dew-point) protected from formation of condensate. The high (adjustable) flow, together with the vacuum, enables a fast response time and reduces adsorption and delay effects to a minimum.
- Operation without consumables
No calibration gas, chemical substances or exchange of service parts required. Minimum operating costs.
- Direct physical measurement
