HealthyPhoton is introducing the new HT1800 TDLAS (Tunable Diode Laser Absorption Spectroscopy) Open-path Hygrometer designed for the eddy covariance method. Since the introduction of the HT8700 Open-path Ammonia Analyzer, we have gradually accumulated experiences in the development and application of instruments in the field of environmental monitoring. Our new HT1800 hygrometer has the open-path configuration that directly measures the moisture content of the atmosphere, ensuring the high accuracy and high speed of measurement. In terms of performance, the instrument fully satisfies the need in the eddy covariance method, and is indispensable in eddy covariance systems for ET analysis and flux corrections of other gas species.

Features and Benefits

• Light weight, low cost, easy installation and maintenance

• Ideal for eddy covariance and evapotranspiration measurements

• Open path configuration, with up to 20Hz measurement frequency

• Ultra-sensitive laser spectroscopy brings very low drift

• No cross-interference from CO₂ and other gas molecules

• No moving parts with strong vibration resistance

• Robust design for versatile field deployment

• Low power (10 W) that can be supplied by a solar panel 

Detection Technology	TDLAS (Tunable Diode Laser Absorption Spectroscopy)
RMS noise  (1σ;  20Hz/10Hz/1Hz)	7 ppm/ 5 ppm/ 2 ppm
Measurement Range	0 - 60 mmol/mol or 0 - 60 pptv
User Interface	Windows based software
Output Data Rate	20 Hz/10 Hz/ 1Hz user configurable
Operating Pressure	70 - 110 kPa
Operating Temperature	-20°C ~ 50°C
Operating Humidity	0 ~ 100% R.H. Non condensing
Data Communication	RS-232
Data Storage	On-board storage with SD card or any data loggers with RS-232 communication interface
Power Requirements	12 VDC
Power Consumption	Typ. 10 W (max. 30 W at warm up )
Dimensions	Sensor Head: L450mm×ø90mm  Control Box: 34cm x 30cm x 15cm  TDL Cable: 3 m (between sensor head and control box)  Power, RS-232, T/A Aux. Input: 3 or 5 m
Weight	Sensor Head: ~2.5kg;   Control Box: ~1.5kg

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  Paper Overview: Measuring Turbulent Water Vapor Fluxes Using a Tunable Diode Laser-Based Open-Path Gas Analyzer
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  Brand Events | HealthyPhoto's First "Cloud" Completes Internal Testing!
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  Measuring evapotranspiration fluxes using a tunable diode laser-based open-path water vapor analyzer
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  Go Carbon Neutral!
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  Eddy Covariance Method for Evapotranspiration Measurements