Tunable Diode Laser (TDL)

Tunable Diode Laser (TDL) is a single line 'monochromatic' spectroscopy technique that offers various measurement advantages including, highly stable calibration, a continuous, fast in situ measurement, and avoidance of cross interference from other gases.

A TDL system consists of a tunable diode laser light source, transmitting optics, an optically accessible absorbing medium, receiving optics and detector(s). The signal information is held in the gas absorption line shape, which is obtained by scanning the laser wavelength over the specific absorption line. This causes a reduction of the measured signal intensity, which is detected by a photodiode and used to determine the gas concentration and other properties. 

Servomex TDL analyzers use a second harmonic detection (2f) modulation technique that delivers greater accuracy, sensitivity and reliability of measurement, especially in low ppm measurements where gas molecule absorption lines are close to other possible interfering components.

Servomex TDL gas analyzers are able to detect a variety of gases including O2, HCl, HF, NH3, CO, CO2, H2O, H2S, HCN, NO, N2O and CH4; making them ideal for cross-stack measurements in process and combustion control applications in Hydrocarbon Processing and Power Generation industries.

Products featuring Servomex TDL technology:

  • LaserSP 2930

    LaserSP 2930

    Rugged cross-stack TDL monitor enables in-situ measurements in extreme environments

  • LaserExact 2950

    LaserExact 2950

    Extractive TDL trace multigas analyzer, designed for measuring trace gases offline

  • LaserCompact 2940

    LaserCompact 2940

    Multigas TDL analyzer designed for cross-stack analysis across short path lengths 

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