Laser Moisture

Laser Moisture analysis delivers a simple, sensitive measurement

An essential technology in our DF-700 series of trace and ultra-trace moisture analyzers, Laser Moisture sensing relies on specially configured Tunable Diode Laser (TDL) spectroscopy to deliver reliable, stable results at very low, industry-leading levels.

This moisture analysis technology uses TDL spectroscopy to measure trace moisture in pure gases. It has a simple, robust design, using a single laser source and single detector to measure the sample and reference gases.

TDL has advantages over other measurement techniques, as the moisture sample comes into contact with only a few optical components made from very robust materials. It works according to the fundamental principle of Beer’s law; therefore the reading is stable over time and never requires calibration.

To provide a more sensitive measurement, our sensors use a Herriott cell to reflect the laser back and forth numerous times, using mirrors inside the measuring cell. This increases the laser path length, achieving extremely high sensitivity.

TDL moisture sensing delivers exceptional performance capable of measuring down to industry-leading sub-ppb levels, drift-free operation, high accuracy and low maintenance. This is achieved through self-correcting optics and laser line locking onto the water peak, removing all possibility of significant drift.

Related and alternative technologies

Laser moisture sensing is paired with Coulometric technology in our DF-760E and DF-760E ULTRA analyzers for industry-best dual measurements of oxygen and moisture at parts-per-million levels. Where ultra-low measurements are not required, it may be more cost-effective to use Aluminum Oxide sensing for moisture monitoring.

Key applications


Ultra-high purity gases

Specialty gases

Key benefits

Exceptional performance down to industry-leading sub-ppb levels

Reading is stable over time – never requires calibration

Laser line lock removes possibility of significant drift

Ideal for

Very low-level trace measurements of moisture as a contaminant in ultra-high purity gases.

Explore the Laser Moisture analyzers we have for your process

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

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Providing trace and ultra-trace moisture contaminant measurements in a variety of background gases, the DF-749 is ideal for quality checking of UHP gases used in LCD and LED manufacture.

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