Phase Structure Function Measurements With Multiple Apertures

Eaton, Frank D.; Peterson, William A.; Hines, John R.; Drexler, J.; Waldie, Arthur Howard; Soules, David B.; Qualtrough, John A.

doi:10.1117/12.960874

Cited by 6 publications

(8 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(3) and using the assumed wide sense stationarity of the wavefront phase perturbations, t), and the odd symmetry of VW( gives t') = ffdd (VW( -) . ) (VW( -) ) D,,t,t') -ffdd (VW(ri) ) (VW() )D(ri,,t,t), (4) 212/SP!E Vol. 2828 where D( , , t, t') is the phase structure function defined by D(',t,t') = ([,t) -(t!…”

Section: Slope Structure Functionmentioning

confidence: 99%

“…This comparison yields the atmospheric parameters of interest like the Fried parameter, r0, in the case of Kolmogorov turbulence statistics [2]. The differential image motion measurement involves sensing the differential motion of the image of a star from two apertures [3,4]. This differential motion can be related to a differential wavefront tilt associated with the two apertures.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of atmospheric turbulence using wavefront slope measurements

Silbaugh¹,

Welsh²,

Roggemann³

1996

SPIE Proceedings

View full text Add to dashboard Cite

Turbulence has long been recognized as one of the most significant factors limiting the performance of optical systems operating in the presence of atmosphere. Atmospheric turbulence over vertical paths has been well characterized, both theoretically and experimentally. Much less is known about turbulence over long, horizontal paths. Perturbations of the wavefront phase can be measured using a Hartmann wavefront sensor (H-WFS). These measurements can be used to characterize atmospheric turbulence directly. Theoretical expressions for the slope structure function of the H-WFS measurements are derived and evaluated using numerical quadrature. By concentrating on the slope structure function, we avoid the phase reconstruction step and use the slope measurements in a more direct fashion. The theoretical slope structure function is compared to estimated slope structure functions computed from H-WFS measurements collected in a series of experiments conducted by researchers at the US Air Force's Phillips Laboratory. These experiments involved H-WFS measurements over high altitude (airborne) horizontal paths 20-200 km in length.

show abstract

Section: Slope Structure Functionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterization of atmospheric turbulence using wavefront slope measurements

Silbaugh¹,

Welsh²,

Roggemann³

1996

SPIE Proceedings

View full text Add to dashboard Cite

show abstract

“…0 else (6) and Ix, I = /x2 + y2. The terms Zx and Zy represent the spatial separation of the subaperture slope measurements normalized by d. The dependence on the coherence diameter r0 and the subaperture dimension d are easily studied here as they are outside the integral.…”

Section: H-wfs Slope Structure Functionsmentioning

confidence: 99%

“…Various methods exist for sensing and measuring this distortion, from differential imaging [6] to interferometry [7]. Recently, a Hartmann Wave Front Sensor (H-WFS) has been used for this purpose [8].…”

Section: Atmospheric Optical Sensing Using a Hartmann Wavefront Sensormentioning

confidence: 99%

Atmospheric turbulence characterization of a low-altitude long horizontal path

Bernard

Welsh²,

Roggemann³

et al. 1996

SPIE Proceedings

View full text Add to dashboard Cite

The limitations placed on optical imaging through the earth's atmosphere are well understood. A large portion of the body of work on this subject deals with vertical optical paths. The transition to the study of horizontal propagation of light is currently being made. Various methods exist that quantify the disturbances introduced on optical signals by turbulent air. Small perturbations of the wave front phase can be measured using a Hartmann Wave Front Sensor (H-WFS). For long optical paths through turbulence spatial and temporal variations in intensity called scintillation arise. Using scintillation statistics and theoretical expressions for structure functions of H-WFS slope values, turbulence strength is studied. Data sets taken from two mountains in Hawaii during an optical communications experiment are studied for comparison with slope structure function and scintillation statistics theory. This experiment was performed at an altitude of 10,000 feet over a horizontal path length of 150 km. Results indicate that very strong scintillation exists under these conditions, and that very little faith can be placed in the H-WFS phase-dependent results. Scintillation may provide a more dependable method for optical characterization of these conditions.

show abstract

“…First, the DDTV technique is insensitive to contamination due to gimbal motion, a feature of all differential-tilt techniques [14, 15,16]. Secondly, additive noise contributions to the differential-tilt variances are inherently canceled in the DDTV technique.…”

Section: Properties Of Ddtv Measurementsmentioning

confidence: 99%

<title>Differential-tilt technique for saturation-resistant profiling of atmospheric turbulence</title>

Whiteley

Washburn

Wright

2002

Adaptive Optics Systems and Technology II

View full text Add to dashboard Cite

A technique for profiling of C over an atmospheric propagation path is proposed, developed and analyzed. The technique employs differential-tilt measurements to arrive at statistics which have unique weighting functions over the propagation path. These weighting functions are computed theoretically and used to derive a reconstructor matrix for C values throughout the path to be applied to an appropriate set of differential-tilt statistics. A candidate optical system is presented, and the performance of the profile reconstructor is analyzed. This study indicates that the relative error in the C estimates is approximately 5%. The relative error in estimating key atmospheric parameters such as the Fried parameter, isoplanatic angle, and the Rytov parameter from the reconstructed profiles is approximately 3%.

show abstract

Phase Structure Function Measurements With Multiple Apertures

Cited by 6 publications

References 0 publications

Characterization of atmospheric turbulence using wavefront slope measurements

Characterization of atmospheric turbulence using wavefront slope measurements

Atmospheric turbulence characterization of a low-altitude long horizontal path

<title>Differential-tilt technique for saturation-resistant profiling of atmospheric turbulence</title>

Contact Info

Product

Resources

About