Laser propagation measurements over a multi-km path in a maritime environment

Fielding TNO’s LPT (Laser Propagation Testbed) for the first time in an international trial, a 3.6 km optical propagation path was created in a maritime environment between the city of Den Helder and the island of Texel in the Netherlands. Using a 1 W, 1556 nm laser beam, atmospheric propagation was investigated by capturing the resulting beam...

Investigating the integrated optical turbulence over the sea by different measurement techniques and mesoscale model simulations

An over-water propagation link of 3.6 km was set up between the Dutch city of Den Helder and the island of Texel. For 6 days in November 2021, a laser beam was propagated along this path. An analysis of the beam wander resulted in an estimate of the strength of optical turbulence Cn 2. Estimates compare quite well with independent measurements...

Low-altitude laser propagation link over a marine surface

A 1.55µm Laser Propagation Testbed (LPT) has been deployed over a 3.5 km stretch of open water between the port of Den Helder and the island of Texel in The Netherlands. The laser intensity and beam profile have been measured after propagation and reflection off a capture plate. Supplementing data was provided by large-aperture scintillometers,...

Near-surface turbulence effects on electro-optical propagation in an arid environment

In the framework of a NATO research group Fraunhofer IOSB and partners conducted a field trial in an arid shrub land environment in southern New Mexico (USA). The group investigates environmental limitations of fielded EO-TDAs (Electro-Optical Tactical Decision Aids). Main objective of the trial was to study the impact of the atmosphere on...

Global simulations of Cn2 using the weather research and forecast model WRF and comparison to experimental results

Electro-optical and laser systems are operated world-wide. Their performance in the outside atmosphere is mainly governed by the strength of optical turbulence Cn2. The predictability of Cn2 using weather-forecast models is investigated by performing simulations with the Weather Research and Forecast Model (WRF). The WRF output data were...

Using ultrasonic anemometers for temperature measurements and implications on Cn2

Investigation of optical turbulence from an unmanned aerial system

Wave propagation of electro-optical systems, lasers or imaging depends on the state of the atmosphere their beams are passing through. Fluctuations in the refractive index of air are responsible for signal attenuation and image degradation. This atmospheric effect is called optical turbulence and its strength is quantified by the structure...

Height dependence of characteristics of power spectra of temperature investigated in the surface layer of White Sands /US

A field trial was performed in the arid scrub area of White Sands, NM /USA in October 2017 investigating the atmospheric influence on imaging and sensor performance. In this paper we focus on the strength of optical turbulence. Optical turbulence is described by the structure function parameter of the refractive index Cn 2. It is responsible for...

Optical turbulence in the coastal area over False Bay /South Africa: Comparison of measurements and modeling results

The atmospheric influence on wave propagation was investigated during the First European South African Transmission ExpeRiment from June 2015 to February 2016. The focus in this article was set on optical turbulence, the main atmospheric factor affecting the position and strength of Laser beams, the performance of electro-optical systems and...

Investigation of the height dependency of optical turbulence in the surface layer over False Bay (South Africa)

Atmospheric turbulence impacts on the propagation of electro-optical radiation. Typical manifestations of optical turbulence are scintillation (intensity fluctuations), beam wander and (for laser systems) reduction of beam quality. For longer propagation channels, it is important to characterize the vertical and horizontal distribution ...

Comparison of integrated optical turbulence over the sea in different coastal regions in the world

Electro-optical and laser systems are presently deployed in naval operations around the world. The performance of these systems is negatively affected by optical turbulence in the atmosphere, quantified by the parameter Cn 2. The strength of the integrated optical turbulence Cn 2 was investigated for several coastal locations in different...

Long-term experiment VERTURM (vertical turbulence measurements): Comparison of measurements and modeling of the vertical distribution of optical turbulence Cn 2 in the surface layer

Operation and design of electro-optical systems are affected by atmospheric turbulence, quantified by refractive structure function parameter Cn 2. The long-term VerTurM experiment at a rural site in Northwestern Germany served to collect an extended dataset of vertical profiles of Cn 2 values up to 64 meters, completed by a characterization of...

Comparison of MODTRAN simulations and transmission measurements by path-integrated and in-situ techniques over a rural site in northwestern Germany

A transmission experiment has been performed over an optical path of 1.53 km at a rural test site in Meppen, Northwest Germany. Direct transmission measurements were made by a 7-wavelength transmissometer. Transmission was further estimated from the average voltage received by a BLS2000 scintillometer, and evaluated with Mie theory from in-situ...

FESTER: A propagation experiment, overview and first results

A long term field trial called FESTER (First European South African Transmission Experiment) has been conducted by an international collaboration of research organizations during the course of almost one year at False Bay, South Africa. Main objectives of the experiment are a better insight into atmospherical effects on propagation of optical...

First results on the Experiment FESTER on optical turbulence over False Bay South Africa: Dependencies and consequences

The experiment FESTER (First European South African Transmission ExpeRiment) took place in 2015 to investigate the atmospheric influence on electro-optical systems performance across False Bay / South Africa on a long term basis. Several permanent stations for monitoring electro-optical propagation and atmospheric parameters were set up around...

The FESTER field trial

An overview is given of the First European - South African Transmission ExpeRiment (FESTER), which took place in South Africa, over the False Bay area, centered around Simon's Town. The experiment lasted from April 2015 through February 2016 and involved continuous observations as well as periodic observations that took place during four...

The dependence of optical turbulence on thermal and mechanical forces over the sea

Optical turbulence for over-water conditions was investigated in a long-term experiment over False Bay near Cape Town, South Africa. A sonic anemometer and two boundary-layer scintillometers were deployed to access in-situ turbulence as well as the integrated turbulence over two 1.8 and 8.7 km paths. Statistical analysis reveals spatial temporal...