Water Vapour Detection (H2O)

Application areas of laser-based water vapour detection

nanoplus lasers for water vapour detection are used for various applications including:

  • Oil & Gas: Water vapour detection in gas pipelines
  • Evironment: Climate monitoring
  • Process Control: Combustion control
  • Automotive: Engine optimization
  • Space: Isotope detection
  • Research: Isotopologue ratio measurements

Tunable diode laser spectroscopy allows measuring H2O with up to ppb precision in real time and in situ. Providing long-term stability and requiring little maintenance, nanoplus lasers are suitable for operation in harsh environments.

Typical wavelengths for water vapour detection

nanoplus offers various wavelengths to target the vibrational-rotational bands of water vapour. Literature recommends the following wavelengths for water vapour detection:

Select your wavelength for water vapour detection

Above wavelengths as well as further customized wavelengths for water vapour detection are available from nanoplus.

When you choose your wavelength, you have to consider your product set up, environment and nature of the measurement.

These factors influence the optimum wavelength for your application. Do have a look at the Hitran Database to further evaluate your choice of wavelengths. Our application experts are equally happy to discuss with you the most suitable wavelength for your application.

Let us know the wavelength you require with an accuracy of 0.1 nm!

Figure 1: Absorption features of water vapour in the 0.76 µm to 6.0 µm range
Absorption features of water vapour in 760 nm to 6000 nm range

Related information for laser-based water vapour detection

Specifications & Mountings


Papers & Links

The following tables analyse the typical specifications of the standard wavelengths for H2O detection.

electro-optical properties of
935.0 nm DFB laser diode
standard wavelengthλnm935.0
absorption line strengthScm / mol∼ 6 x 10-22
output powerpoutmW20
threshold currentlthmA152025
current tuning coefficientcTnm / mA0.010.020.025
temperature tuning coefficientcInm / K0.070.080.09
mode hop free tuning rangeΔλnm+/- 0.5
electro-optical properties of
1392.0 nm DFB laser diode
standard wavelengthλnm1392.0
absorption line strengthScm / mol∼ 1 x 10-20
output powerpoutmW5
threshold currentlthmA102530
current tuning coefficientcTnm / mA0.010.020.03
temperature tuning coefficientcInm / K0.070.100.14
mode hop free tuning rangeΔλnm+/- 0.5
electro-optical properties of
2682.0 nm DFB laser diode
standard wavelengthλnm2682.0
absorption line strengthScm / mol∼ 3 x 10-19
output powerpoutmW2
threshold currentlthmA305080
current tuning coefficientcTnm / mA0.010.020.05
temperature tuning coefficientcInm / K0.150.20.28
mode hop free tuning rangeΔλnm+/- 0.5
mounting options /
technical drawings
wavelengthTECcap with windowAR cap with AR windowfiberheatsinkcollimation
TO5.6 760 nm - 3000 nmNANANANANA
TO5 760 nm - 3000 nmNANA
TO663000 nm - 6000 nmNANA
c-mount 760 nm - 3000 nmNANANANANANA
SM-BTF760 nm - 2360 nmNANAsingle modeNANA
PM-BTF1064 nm - 2050 nmNANApolarization maintainingNANA

Ask for further packages.

Please find below a number of application samples.

Combustion control in high temperature processes:
Water vapour is often examined in combustion and propulsion processes as it is a primary product of hydrogen and hydrocarbon fuels. [15, 16, 17, 28, 65, 70]

Isotope detection by NASA Mars Rover Curiosity:
NASA’s flagship Rover Curiosity detects CO2 and H2O isotopes based on their tunable laser spectrometer SAM. The analysis of soil samples is to determine whether Mars is or has been a suitable living environment. We are proud that the instrument uses a 2.78 µm nanoplus laser for this measurement. [25]

Isotopologe ratio measurements:
Water isotopologue measurements are carried out in various research fields like climate and paleoclimate studies, geological surveys, hydrological studies, and clinical research for diagnosis. [30]

Monitoring of climate processes:
Ecologists are worried about the melting of permafrost soils in the northern hemisphere. Greenhouse gases like CO2 or CH4 that are stored in the soil might be released in this case. Another, less observed, thread comes from the evaporation and condensation of large water vapor volumes. A laser-based hygrometer for mobile field applications has been developed. It measures water vapour in situ and at low concentrations. An airborn approach for monitoring climate processes is the use of a multi-wavelength H2O-Differential Absorption Lidar. It examines the whole troposphere and lower stratosphere simultaneously. [21, 46]

Optimization of internal combustion engines:
The automotive industry designs new engines to increase fuel efficiency and reduce pollutant emission. Exhaust gas recirculation has become a standard technology for emission control. A newly developed laser hygrometer measures water vapour in such engines with microsecond time resolution and in situ. This method helps to rapidly quantify recirculated gas fractions and to eventually optimize combustion. [47]

Quality control in natural gas pipelines:
Water vapour measurement is critical for gas companies to meet quality specifications and to protect pipelines from corrosion. False positives are very costly. Often the gas cannot be delivered if it is "wet".

Please find below a selection of related papers from our literature list.

Let us know if you published a paper with our lasers. We will be happy to include it in our literature list.

#4 Laser-Based Analyzers – Shining New Stars;
P. Nesdore, Gases & Instrumentation, March/April 2011, pp. 30-33.

#9 DFB Lasers Between 760 nm and 16 µm for Sensing Applications;
W. Zeller, L. Naehle, P. Fuchs, F. Gerschuetz, L. Hildebrandt, J. Koeth, Sensors 2010, 10, pp. 2492-2510.

#15 Scanned-wavelength-modulation spectroscopy near 2.5 µm for H2O and temperature in a hydrocarbon-fueled scramjet combustor;
C. S. Goldenstein, I. A. Schultz, R. M. Spearrin, J. B. Jeffries, R.K. Hanson, Appl. Phys. B, 116, 3, Sept 2014, pp 717-727.

#16 Diode laser measurements of linestrength and temperature-dependent lineshape parameters of H2O-, CO2-, and N2-perturbed H2O transitions near 2474 and 2482 nm;
C.S. Goldenstein, J.B. Jeffries, R.K. Hanson, J. of Quantitative Spectr. & Radiative Transfer 130, 2013, pp. 100–111.

#17 Wavelength-modulation spectroscopy near 2.5 µm for H2O and temperature in high-pressure and -temperature gases;
C.S. Goldenstein, R.M. Spearrin, J.B. Jeffries, R.K. Hanson, Appl. Phys. B, 116, 3, Sept 2014, pp 705-716.

#19 Measurements of Mars Methane at Gale Crater by the SAM Tunable Laser Spectrometer on the Curiosity Rover;
C.R. Webster, P.R. Mahaffy, S.K. Atreya, G.J. Flesch, K.A. Farley, 44th Lunar and Planetary Science Conference, March 18-22, 2013, LPI Contribution No. 1719, p.1366.

#21 The airborne multi-wavelength water vapor differential absorption lidar WALES: system design and performance;
M. Wirth, A. Fix, P. Mahnke, H. Schwarzer, F. Schrandt, G. Ehret, Appl. Phys. B, 96, 1, July 2009, pp. 201-213.

#25 Isotope Ratios of H, C, and O in CO2 and H2O of the Martian Atmosphere;
C.R. Webster, P.R. Mahaffy, G.J. Flesch, P.B. Niles, J. Jones, L.A. Leshin, S.K. Atreya, J.C. Stern, L.E. Christensen, T. Owen, H. Franz, R.O. Pepin, A. Steele, Science, 341, 6143, 2013, pp. 260-263.

#28 In situ combustion measurements of H2O and temperature near 2.5 µm using tunable diode laser absorption;
A. Farooq, J.B Jeffries, R.K Hanson, Meas. Sci. Technol., 19, 2008, 075604, pp. 11.

#30 Kalman filtering real-time measurements of H2O isotopologue ratios by laser absorption spectroscopy at 2.73 µm;
T. Wu, W. Chen, E. Kerstel, E. Fertein, X. Gao, J. Koeth, Karl Roessner, D. Brueckner, Opt. Lett., 35, 5, 2010, pp. 634.636.

#34 High power pulsed 976 nm DFB laser diodes;
W. Zeller, M. Kamp, J. Koeth, L. Worschech, Proc. SPIE 7682, Photonic Microdevices/Microstructures for Sensing II, 76820T, 2010.

#46 TDLAS-based open-path laser hygrometer using simple reflective foils as scattering targets;
A. Seidel, S. Wagner, V. Ebert, Appl. Phys. B, 109, 3, Nov. 2012, pp. 497-504.

#47 High-speed tunable diode laser absorption spectroscopy for sampling-free in-cylinder water vapor concentration measurements in an optical IC engine;
O. Witzel, A. Klein, S. Wagner, C. Meffert, C. Schulz, V. Ebert, Appl. Phys. B, 109, 3, Nov. 2012, pp. 521-532.

#51 Noninvasive monitoring of gas in the lungs and intestines of newborn infants using diode lasers: feasibility study;
P. Lundin, E.K. Svanberg, L. Cocola, M.L. Xu, G. Somesfalean, S. Andersson-Engels, J. Jahr, V. Fellman, K. Svanberg, S. Svanberg, J. of Biomed. Opt., 18(12), Dec. 2013, 127005.

#65 H2O temperature sensor for low-pressure flames using tunable Diode laser Absorption near 2.9 µm;
S. Li, A. Farooq, R.K. Hanson, Meas. Sci. Technol., 22, 2011, pp. 125301-125311.

#71 Novel utilisation of a circular multi-reflection cell applied to materials ageing experiments;
D.A. Knox, A.K. King, E.D. McNaghten, S.J. Brooks, P.A. Martin, S.M. Pimblott, App. Phys. B, 2015, 119, pp. 55-64.

#73 Time-multiplexed open-path TDLAS spectrometer for dynamic, sampling-free, Interstitial H218O and H216O vapor detection in ice clouds;
B. Kuehnreich, S. Wagner, J.C. Habig, O. Moehler, H. Saathoff, V. Ebert, App. Phys. B, 2015, 119, pp. 177-187.