Laser 3 Plus Combustion Tunable Diode Laser
Tunable Diode Laser

Obtain fast, in-situ cross-stack measurements with TDL sensing

Tunable Diode Laser (TDL) technology offers a fast-response, accurate measurement that is highly specific to the gas of interest. This non-contact, non-depleting sensing is used in our innovative, compact SERVOTOUGH Laser 3 Plus range of analyzers.

Tunable Diode Laser (TDL) analyzers use a single-line “monochromatic” spectroscopic technique that offers highly stable calibration, a continuous, fast, in-situ measurement, and the avoidance of optical cross-interference from other gases.

The TDL system consists of a 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.

Our TDL analyzers use a second harmonic detection (2f) modulation technique that delivers greater accuracy, sensitivity and reliability of measurement, especially in low ppm-level measurements.

Related and alternative technologies

TDL sensing can work alongside Zirconia sensors in combustion applications, providing complementary carbon monoxide and methane measurements. It is susceptible to a range of environmental factors that must be compensated for, including path length variation, window purge gas effects, optical interferences and temperature and pressure changes. A specially configured version of TDL sensing is used in our Laser Moisture analyzers.

Key applications

Process and combustion control

Ammonia slip DeNOx measurements

Safety monitoring

Key benefits

A fast response to changing gas concentrations

Highly specific to the gas being measured

Line lock system prevents signal drift

Ideal for

Cross-stack measurements in process and combustion control applications in hydrocarbon processing and power generation industries.

Explore the TDL analyzers we have for your process

Learn more about all our gas analyzer solutions that use this sensor technology.

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SERVOTOUGH Laser 3 Plus Combustion

SERVOTOUGH Hazardous Area

Unmatched installation flexibility plus cost and performance benefits, ready for fast, accurate and responsive measurements in combustion and process control.

Laser 3 Plus Combustion Tunable Diode Laser
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SERVOTOUGH Laser 3 Plus Environmental

SERVOTOUGH Hazardous Area

Compact, high-performance Tunable Diode Laser (TDL) analyzer, specifically optimized for ammonia slip measurement

SERVOTOUGH Laser 3 Plus Environmental
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SERVOTOUGH Laser 3 Plus Process

SERVOTOUGH Hazardous Area

Optimized for the fast, accurate and responsive measurement of process oxygen (O2) in hot or hazardous conditions.

Laser 3 Plus Process Tunable Diode Laser (TDL) analyzer
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Need more advice? Contact the gas analysis experts today

If you still need guidance to find the best solution for your process, we’re here to help. Our expert team combines applications knowledge with extensive experience and deep understanding of the sensing technologies available. We’ll help you find the solution that meets your unique needs.


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