Spatial-heterodyne sampling requirements in the off-axis pupil plane recording geometry for deep-turbulence wavefront sensing

Banet, Matthias T.; Spencer, Mark F.

doi:10.1117/12.2275145

Cited by 6 publications

(5 citation statements)

References 5 publications

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“…We find that the nlCWFS must sample the beam by at minimum ∼4 to 5 pixels per r0, as defined in the pupil plane, for a reconstruction that produces a field-estimated Strehl ratio sufficient for diffraction-limited performance (S≈0.8). This value is similar to results found for the digital holographic WFS, 25 which is not surprising given that both sensors rely on optical interference to reconstruct the wavefront.…”

Section: Resultssupporting

confidence: 85%

“…The resulting images were then binned for sampling tests by increasing factors of 2, 4, 8, and 16. The field-estimated Strehl ratio (S) was used as the primary metric for assessing performance 25 . Results of the analysis are shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The field-estimated Strehl ratio (S) was used as the primary metric for assessing performance. 25 Results of the analysis are shown in Fig. 12.…”

Section: Spatial Sampling Requirementsmentioning

confidence: 99%

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Assessing phase reconstruction accuracy for different nonlinear curvature wavefront sensor configurations

Letchev,

Crass,

Crepp

2023

J. Astron. Telesc. Instrum. Syst.

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.The nonlinear curvature wavefront sensor (nlCWFS) offers improved sensitivity for adaptive optics systems compared with existing WFSs, such as the Shack–Hartmann. The nominal nlCWFS design uses a series of imaging planes offset from the pupil along the optical propagation axis as inputs to a numerically iterative reconstruction algorithm. Research into the nlCWFS has assumed that the device uses four measurement planes configured symmetrically around the optical system pupil. This assumption is not strictly required. In this paper, we perform the first systematic exploration of the location, number, and spatial sampling of measurement planes for the nlCWFS. Our numerical simulations show that the original, symmetric four-plane configuration produces the most consistently accurate results in the shortest time over a broad range of seeing conditions. We find that the inner measurement planes should be situated past the Talbot distance corresponding to a spatial period of r0. The outer planes should be large enough to fully capture the field intensity and be situated beyond a distance corresponding to a Fresnel-number-scaled equivalent of Z ≈ 50 km for a D = 0.5 m pupil with λ = 532 nm. The minimum spatial sampling required for diffraction-limited performance is 4 to 5 pixels per r0 as defined in the pupil plane. We find that neither three-plane nor five-plane configurations offer significant improvements compared with the original design. These results can impact future implementations of the nlCWFS by informing sensor design.

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Section: Resultssupporting

confidence: 85%

Section: Resultsmentioning

confidence: 99%

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Assessing phase reconstruction accuracy for different nonlinear curvature wavefront sensor configurations

Letchev,

Crass,

Crepp

2023

J. Astron. Telesc. Instrum. Syst.

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“…This was done using a similar method to the defocus distance testing and followed the example of Banet et al 2017 for digital holography. 9 A separate series of 16 wavefronts were created for D/r 0 values of 4, 6, 8, and 10, for which the results were averaged for statistical relevance. These wavefronts were then reconstructed using a symmetric-four-plane nlCWFS configuration with measurement planes located at the optimal distances derived from the analysis described in Section 3.2.…”

Section: Spatial Sampling Requirementsmentioning

confidence: 99%

“…The field-estimated Strehl ratio (S F ) was used as the main metric for performance, so as to easily compare results to the Banet et al 2017 digital holography analysis. 9 This metric also helps to avoid phase unwrapping effects which could impact the RMS residual WFE more strongly than the field-estimated Strehl ratio.…”

Section: Spatial Sampling Requirementsmentioning

confidence: 99%

Spatial frequency response and sensitivity of the non-linear curvature wavefront sensor

Letchev

Crass

Crepp

et al. 2022

Adaptive Optics Systems VIII

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The nonlinear curvature wavefront sensor (nlCWFS) has been shown to be a promising alternative to existing wavefront sensor designs. Theoretical studies indicate that the inherent sensitivity of this device could offer up to a factor of 10× improvement compared to the widely-used Shack-Hartmann wavefront sensor (SHWFS). The nominal nlCWFS design assumes the use of four detector measurement planes in a symmetric configuration centered around an optical system pupil plane. However, the exact arrangement of these planes can potentially be optimized to improve aberration sensitivity, and minimize the number of iterations involved in the wavefront reconstruction process, and therefore reduce latency. We present a systematic exploration of the parameter space for optimizing the nlCWFS design. Using a suite of simulation tools, we study the effects of measurement plane position on the performance of the nlCWFS and detector pixel sampling. A variety of seeing conditions are explored, assuming Kolmogorov turbulence. Results are presented in terms of residual wavefront error following reconstruction as well as the number of iterations required for solution convergence. Alternative designs to the symmetric four-plane design are studied, including three-plane and five-plane configurations. Finally, we perform a preliminary investigation of the effects of broadband illumination on sensor performance relevant to astronomy and other applications.

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Air Force Research Laboratory, Aero-Effects Laboratory optical metrology system and performance

et al. 2020

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Spatial-heterodyne sampling requirements in the off-axis pupil plane recording geometry for deep-turbulence wavefront sensing

Cited by 6 publications

References 5 publications

Assessing phase reconstruction accuracy for different nonlinear curvature wavefront sensor configurations

Assessing phase reconstruction accuracy for different nonlinear curvature wavefront sensor configurations

Spatial frequency response and sensitivity of the non-linear curvature wavefront sensor

Air Force Research Laboratory, Aero-Effects Laboratory optical metrology system and performance

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