Aberration measurements in speckle field by Shack–Hartmann wavefront sensor

Goloborodko, Andrey A.; Kotov, Myhailo M.; Kurashov, Vitalij N.; Podanchuk, Dmytro V.

doi:10.1117/1.oe.55.12.121710

Cited by 3 publications

(2 citation statements)

References 19 publications

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“…Phase errors cause additional phase noise, which leads to the speckles in the Shack-Hartman sensor im-age plane [12]. High spatial frequencies of the phase noise (a small amount of noise pixels) could be filtered by using lenses L4 and L5 [23]. However, the present paper does not deal with noise filtering and the effect of unfiltered noise on the wavefront restoration can be found in the next Subsection.…”

Section: A Wavefront Generation and Calibrationmentioning

confidence: 99%

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Effect of noise and pixel size on the wavefront generated by amplitude holograms

Goloborodko¹

2019

J. Phys. Stud.

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The possibilities of wavefront generation by amplitude holograms are theoretically and experimentally investigated. Holograms could be generated in any PC using a MATLAB program developed by the author. The wavefronts of the generated holograms are obtained experimentally and confirmed by theoretical calculations both qualitatively and quantitatively. The errors of wavefront restoration are obtained on the example of the first 12 Zernike aberrations. The effect of the pixel size and pixelate noise on hartmanogramms of the generated wavefront and restored wavefronts are experimentally investigated.

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Section: A Wavefront Generation and Calibrationmentioning

confidence: 99%

“…On the other hand, it can be also observed, that an increase in the noise intensity leads to an increase in the amplitude of higher modes (Fig. 7), at the same time the variation of the coefficient increases too [13,23].…”

Section: B Noise Effectmentioning

confidence: 99%

Effect of noise and pixel size on the wavefront generated by amplitude holograms

Goloborodko¹

2019

J. Phys. Stud.

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Temporally averaged speckle noise in wavefront sensors for beam projection in weak turbulence

et al. 2021

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Adaptive optics (AO) compensation for imaging or coherent illumination of a remote object relies on accurate sensing of atmospheric aberrations. When a coherent beacon is projected onto the object to enable wavefront sensing, the reflected reference wave will exhibit random variation in phase and amplitude characteristics of laser speckle. In a Shack–Hartmann wavefront sensor (SHWFS) measurement, speckle effects cause fluctuations in the intensity of focal spots and errors in the position of their centroids relative to those expected from purely atmospheric phase aberrations. The resulting error in wavefront measurements negatively impacts the quality of atmospheric phase conjugation. This paper characterizes the effect of reflected laser speckle on the accuracy of SHWFS measurements for ground-to-space beam projection systems in weak turbulence conditions. We show via simulation that the speckle-induced error in centroiding depends on the ratio between beacon diameter and the diffraction-limited resolution of the lenslet and confirm these results with experimental data. We provide experimental validation that averaging of SHWFS lenslet spot intensities over speckle realizations converges to the incoherent intensity as expected. We further show that the effects of shot noise and speckle noise add in quadrature, simplifying noise analysis. Finally, we characterize the effect of temporal averaging under typical conditions of target motion and integration time. This work provides a straightforward set of relations that can help investigators more accurately estimate the required integration time for wavefront sensing in the presence of laser speckle.

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Wavefront curvature restoration by a sensor based on the Talbot phenomenon under Gaussian illumination

Goloborodko¹

2023

J. Opt. Soc. Am. A

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The present paper deals with the accuracy of wavefront curvature restoration based on pit displacement measurements in a Talbot wavefront sensor under Gaussian illumination conditions. The measurement possibilities of the Talbot wavefront sensor are theoretically investigated. A theoretical model based on the Fresnel regime is used to determine the intensity distribution in the near field, and the effect of the Gaussian field is described in terms of the spatial spectrum of the grating image. The effect of wavefront curvature on the measurement error of the Talbot sensor is discussed—particularly, the measurement of wavefront curvature is investigated.

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Aberration measurements in speckle field by Shack–Hartmann wavefront sensor

Cited by 3 publications

References 19 publications

Effect of noise and pixel size on the wavefront generated by amplitude holograms

Effect of noise and pixel size on the wavefront generated by amplitude holograms

Temporally averaged speckle noise in wavefront sensors for beam projection in weak turbulence

Wavefront curvature restoration by a sensor based on the Talbot phenomenon under Gaussian illumination

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