Laser Absorption Spectroscopy
LAS - Laserabsorption Spectroscopy
The highly precise Laser Absorption Spectroscopy (LAS) measurement principle is based on the absorption of specific light wavelengths by molecules to be detected.
The infrared laser is tunable to 1/1.000 cm-1 wave numbers and long-term stabilized to the corresponding absorption wavelengths.
The determination of the concentration follows the Lambert-Beer’s light absorption law, evaluating the relation between the intensity of transmitted (I) to incident light (I0) at the detector.
The method is not subjected to drift and insensitive to pollution.
The measured spectrum and the model for the instrument function are compared with the HITRAN database containing the theoretical absorption spectrum of a specific gas. The analysis algorithm continuously verifies the absence of divergences and ensures a correct measurement.
Should the measured spectrum ever differ from the theoretical spectrum, the system issues a warning. In this situation users can visually inspect the
absorption spectrum to discover the reason fast.
- Benefits at a glance
- Direct physical measurement
Selective and continuous measurement of the concentration from the spectrum in Near-IR to MID-IR range. Real spectroscopy (no measurement of auxiliary parameters)
- End-calibration-free an physically traceable
No regular calibration of the end point is required, since the measurement is exclusively based on Lambert-Beer’s light absorption law and the HITRAN database. As influences of other parameters are absent, the measurement is calibration-free and physically traceable. Time-consuming calibration procedures not necessary.
- No cross sensitivities
The narrow-band tunable laser source ensures highest selectivity for the measured gas. A plausibility check of the transmission spectrum is continuously running, profiting from a smart algorithm. Misinterpretation of the results is prevented.
• Selective measurement of the measured gas in every operating state
• Divergencies arereliably detected and users are informed by means of a warning- 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.
• Outstanding conditions for safe plant control and optimized cycle times- Operation without consumables
No calibration gas, chemical substances or exchange of service parts required. Minimal operating costs.
