Polychromatic wave-optics models for image-plane speckle 1 Well-resolved objects

Zandt, Noah R. Van; McCrae, Jack E.; Spencer, Mark F.; Steinbock, Michael J.; Hyde, Milo W.; Fiorino, Steven T.

doi:10.1364/ao.57.004090

Cited by 24 publications

(5 citation statements)

References 43 publications

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“…In this paper, we make use of the commonly used split-step BPM, which simulates the propagation of monochromatic and polychromatic light through the atmosphere. [47][48][49][50] As described by Schmidt, 51 the split-step BPM divides the propagation path into independent volumes, with the atmospheric aberrations in each volume being represented by a single phase screen. The splitstep BPM makes use of angular spectrum or plane-wave spectrum propagation to vacuumpropagate the light from a source plane to the first phase screen, applies the phase screen, and repeats this process until the monochromatic light reaches a target plane.…”

Section: Split-step Beam Propagation Methodsmentioning

confidence: 99%

Wave-optics investigation of turbulence thermal blooming interaction: I. Using steady-state simulations

Spencer

2020

Opt. Eng.

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Part I of this two-part paper uses wave-optics simulations to look at the Monte Carlo averages associated with turbulence and steady-state thermal blooming (SSTB). The goal is to investigate turbulence thermal blooming interaction (TTBI). At wavelengths near 1 μm, TTBI increases the amount of constructive and destructive interference (i.e., scintillation) that results from high-power laser beam propagation through distributed-volume atmospheric aberrations. As a result, we use the spherical-wave Rytov number and the distortion number to gauge the strength of the simulated turbulence and SSTB. These parameters simplify greatly given propagation paths with constant atmospheric conditions. In addition, we use the log-amplitude variance and the branch-point density to quantify the effects of TTBI. These metrics result from a point-source beacon being backpropagated from the target plane to the source plane through the simulated turbulence and SSTB. Overall, the results show that the log-amplitude variance and branch-point density increase significantly due to TTBI. This outcome poses a major problem for beam-control systems that perform phase compensation. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Split-step Beam Propagation Methodsmentioning

confidence: 99%

Wave-optics investigation of turbulence thermal blooming interaction: I. Using steady-state simulations

Spencer

2020

Opt. Eng.

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“…However, the speckle can vary over the bandwidth via two other mechanisms: (1) transverse object motion, rotation, or vibration over the image collection time and (2) the diffraction angles changing with frequency, which is referred to in Refs. 2 and 15.…”

Section: Theorymentioning

confidence: 99%

Speckle decorrelation effects on motion-compensated, multi-wavelength 3D digital holography: theory and simulations

Banet

Fienup

2023

Opt. Eng.

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.Digital holography enables 3D imagery after processing frequency-diverse stacks of 2D coherent images obtained from a chirped-frequency illuminator. To compensate for object motion or vibration, which is a common occurrence for long-range imaging, a constant temporal frequency or “pilot-tone” illuminator can act as a reference for each chirped frequency. We examine speckle decorrelation between the chirped and pilot-tone illuminators and its effect on the resultant range images. We show that speckle decorrelation between the two illuminators is more severe for facets of the object’s surface that are more highly sloped, relative to the optical axis, and that this decorrelation results in noise in the range images in the areas of the object that are highly sloped. We develop a theoretical framework along with wave-optics simulations for 3D imaging with a pilot tone, and we examine the severity of this noise as a function of several imaging parameters, including the illumination bandwidth, pulse frequency spacing, and atmospheric turbulence strength; we show that 3D sharpness metric maximization can mitigate some of the noise induced by turbulence, all in a simulated framework.

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“…53 This toolbox uses the split-step beam propagation method (BPM) to simulate the propagation of monochromatic and polychromatic light through the atmosphere. [15][16][17][18][19][20][21][22] In practice, the split-step BPM divides the atmosphere into independent volumes, such that a phase screen represents the atmospheric aberrations present in a volume. Angular-spectrum propagation to each phase screen (from the source plane to the pupil plane) then represents the propagation of light through the atmosphere.…”

Section: Setup and Explorationmentioning

confidence: 99%

“…), which typically require the use of high-fidelity and wave-optics simulations. [15][16][17][18][19][20][21][22] For example, Voitsekhovich et al 23 were the first to perform a wave-optics investigation of branch-point density (i.e., the number of branch points within the pupil-phase function). They did so as a function of propagation distance with the effect of a finite inner scale but for a fixed grid sampling.…”

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Wave-optics investigation of branch-point density

et al. 2022

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We use wave-optics simulations to investigate branch-point density (i.e., the number of branch points within the pupil-phase function) in terms of the grid sampling. The goal for these wave-optics simulations is to model plane-wave propagation through homogeneous turbulence, both with and without the effects of a finite inner scale modeled using a Hill spectrum. In practice, the grid sampling provides a gauge for the amount of branch-point resolution within the wave-optics simulations, whereas the Rytov number, Fried coherence diameter, and isoplanatic angle provide parameters to setup and explore the associated deep-turbulence conditions. Via Monte Carlo averaging, the results show that without the effects of a finite inner scale, the branch-point density grows without bound with adequate grid sampling. However, the results also show that as the inner-scale size increases, this unbounded growth (1) significantly decreases as the Rytov number, Fried coherence diameter, and isoplanatic angle increase in strength and (2) saturates with adequate grid sampling. These findings imply that future developments need to include the effects of a finite inner scale to accurately model the multifaceted nature of the branch-point problem in adaptive optics.

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Polychromatic wave-optics models for image-plane speckle 1 Well-resolved objects

Cited by 24 publications

References 43 publications

Wave-optics investigation of turbulence thermal blooming interaction: I. Using steady-state simulations

Wave-optics investigation of turbulence thermal blooming interaction: I. Using steady-state simulations

Speckle decorrelation effects on motion-compensated, multi-wavelength 3D digital holography: theory and simulations

Wave-optics investigation of branch-point density

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