A continuous‐wave, lidar sensor based on water vapour absorption lines at 1.52 μm

ABSTRACT

A method to measure long-range distances (>100 m) using a continuous-wave laser is presented. A continuous-wave laser beam at a wavelength in resonance with the water vapour absorption lines of water vapours at 1.52 μm is propagated to an object at a distance of 750 m, and the back-reflected signal is recorded. The atmospheric parameters (vapour pressure, temperature, atmospheric pressure) were recorded simultaneously with the laser back-reflection measurements. The water vapour concentration in the atmosphere is calculated from the atmospheric parameters. The distance from the laser sensor to the object is calculated using the differential absorption lidar (DIAL) method and the water vapour concentration. A 22 h experiment was performed to validate the methodology effectiveness during diurnal weather variation. Two water vapour absorption lines were used to calculate the distance to the object. The calculated distances were found to be 730 m ± 20 and 720 m ± 30 (2.7% and 4.0% deviation, respectively, compared to the actual distance).

Acknowledgments

We would like to express our gratitude to Dr Nektarios Chrysoulakis and Mr Konstantinos Politakos for providing the weather data.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was co-funded by the European Commission in the framework of the LIFE17 CCM/GR/000087 project “Innovative technologies for climate change mitigation by Mediterranean agricultural sector (LIFE ClimaMed)”.