Denis W. Oesch

Estimation of Kolmogarity through isotropy

We develop a metric that measures the isotropy of atmospheric turbulence. We then apply that metric to data from the RACHL experiment as a test of the Kolmogarity of the turbulence encountered in that experiment.

An overview of the RACHL Experiment

An experiment, specifically undertaken in order to measure terrestrial turbulence-induced photonic orbital angular momentum, was conducted at the RACHL site at the Starfire Optical Range. We present an overview of the experiment, to include methodology and calibration.

Photonic Orbital Angular Momentum in Turbulence: Three Experiments at Starfire Optical Range

The results of three experiments sampling distinctly different conditions for turbulence-induced photonic orbital angular momentum are compared and contrasted.

POAM in starlight: seven years of SAM measurements

At the Starfire Optical Range in 2011, the first measurements of photonic orbital angular momentum in starlight were made. Although that survey conclusively demonstrated that POAM exists in starlight, the survey was limited. We have subsequently obtained access to the SAM data archive with its seven years of data. Here the SAM data is analyzed to include the two metrics, branch point density, ρ , and the conversion efficiency η, that were used in the analysis of the 2011 observations.

Description of a technique to use POAM to estimate wind velocity

The turbulent atmosphere induces photonic orbital angular momentum (POAM) on a propagating laser beam. Conventional wave front sensor measurements can use POAM to interrogate the velocity of the atmosphere.

Anticorrelation of the Optical Vortex Density and the Fried Parameter in RACHL Data

The RACHL experiment interrogated the dependence of the measured optical vortex density on the turbulence strength, represented by the Fried parameter. We found that a strong correlation extends down to the scale of individual frames.

Zero Crossing Features of Branch Point Phase

Branch points arise in propagation through strong turbulence or propagation over long distances in weak turbulence. Since branch points are zeros in the field amplitude, they can be represented as the intersection of the zero contours of the real and imaginary parts of the field. The relationship between complex analytic functions, the intersection angle of the zero contours and the irrotational and rotational (hidden) phase is considered.

Turbulence-induced Optical Vortex Trails in Light from HR 1577

The 2011 SOR observations of HR 1577 were reanalyzed using projections of the helicity spectrum. The method demonstrated optical vortex trails in each of the HR 1577 observations.

Characterizing Earth’s Boundary Layer (CEBL)—2014 Update

AFRL is developing a model of boundary layer turbulence. A field campaign, correlating meteorological conditions with measured turbulence, is being conducted to anchor the model. We present the 2014 update on the campaign.

A First Look at Starfire Optical Range Atmospheric Monitor Data for Photonic Orbital Angular Momentum

A first look for photonic orbital angular momentum in five years of atmospheric profiling data from the Starfire Optical Range Atmospheric Monitor is presented.