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Home / Laser systems / TDLAS Instrument / TDLAS Laser Gas Detection Instrument

TDLAS Laser Gas Detection Instrument

What is TDLAS Technology?

Tunable Diode Laser Absorption Spectroscopy is short for TDLAS. It adopts a specially-made semiconductor laser source, which locks its wavelength to a near-infrared absorption peak of gas, and analyzes the change of optical signal passing through the gas to realize concentration detection. The measured gases include CH4, NH3, H2O, N2O, O2, CO, CO2, H2S, HCl and some hydrocarbons. Because the absorption peak of gas in the near infrared spectrum is usually very sharp, the measurement is not easily interfered by coexisting gas, and has excellent specificity. Compared with traditional technology, the detection limit and sensitivity have obvious advantages. In addition, TDLAS technology can realize new applications such as remote measurement and distributed optical fiber measurement, which is a promising optical gas detection technology.

What Do We Offer?

Our control box provides a complete electronic and software system for implementing TDLAS. The user only needs to install the selected laser into the control box, the detection light is led out by the optical fiber, and then the preamplifier signal of the receiving tube is connected back, so that the PC can control the detection and observe the results.

The whole WMS (Wavelength Modulation Spectroscopy) operation is adopted in the system. (1) The laser is modulated by low-frequency triangle wave and high-frequency sine wave, and the echo is detected by phase-locking at 1 and 2 times. Hardware includes digital waveform generator, laser driver, temperature controller, variable gain amplifier, filter and digital lock-in amplifier. The equipment also has built-in proprietary algorithm, which can give the final result (2) of gas concentration optical path product, providing convenience for users.

Name Price Operation
TDLAS Laser Gas Detection Instrument
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Key Parameter






Butterfly-shaped   14pins

Modulating frequency


Drive current


Demodulation mode

1f,2f digital quadrature

TEC current

1A max.

DAC output

1f,2f optional,   0 ~ 2.5V.

Temperature control range


Communication interface

USB, Modbus, 4-20mA

Analog input range


Sensitivity of detection   (2)

50 ppm X m

Modulation system

Triangular wave + sine wave

Detection range (2)

0~50000 ppm X m


(1) Pawel Kluczynski, Jörgen Gustafsson,, Wavelength modulation absorption spectrometry — an extensive scrutiny of the generation of signals,  Spectrochimica Acta Part B: Atomic Spectroscopy, Volume 56, Issue 8, 2001, Pages 1277-1354

(2) The proprietary algorithm aims at the absorption peak of methane at @1653.7nm, and other gases and wavelengths need to be customized.


The main parameters in THE WMS algorithm and the working state of the instrument can be set by connecting the instrument with USB port. You can view the 1f and 2f demodulation waveform directly through the software, or set the output to the oscilloscope through the DAC interface.

※Requires a PC running Windows with a USB port.