Digital holography wavefront sensing with a supersonic wind tunnel

Wilcox, Christopher C.; Radosevich, Cameron J.; Healy, Keith P.; Tuffli, Andrea L.; Agena, Brian D.; Spencer, Mark F.; Wittich, Donald J.

doi:10.1117/12.2521337

Cited by 4 publications

(2 citation statements)

References 6 publications

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“…This process is described in further detail in Wilcox at al. 18 The total intensity of the fringe pattern, I, is the superposition of the complex optical fields for signal and reference beams, U S and U R , respectively. This is defined as…”

Section: Digital Holography Wavefront Sensormentioning

confidence: 99%

Studies of local shock effects on Shack-Hartmann and digital holography wavefront sensors

Chu,

Bukowski,

Gordeyev

2023

Unconventional Imaging, Sensing, and Adaptive Optics 2023

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At supersonic speeds, shock waves create steep gradients in the density of the flow field. These large gradients have been shown to adversely affect the accuracy of Shack-Hartmann Wavefront Sensor (SHWFS) during wavefront reconstruction. This is caused by higher-order beam distortions within the lenslet. In the presented work, the wavefront of a collimated beam propagating through a local shock region over a partially protruding cylinder body was measured using SHWFS and off-axis Digital Holography Wavefront Sensor (DHWFS). These measurements were taken simultaneously allowing for direct comparison. Further study was done on computational and postprocessing methods of handling the higher order aberrations caused by the shock, as well as studying their effects on the resulting wavefront. By varying the incoming transonic Mach numbers, the shock strength and spatial extent could be adjusted, thus providing multiple scenarios for comparison. The experimental data presented in this work provides valuable insight into shock-induced effects on the resulting wavefront. These results help to further support the development of new methods for mitigating the adverse effects of shocks on well-established measurement methods such as SHWFS and off-axis DHWFS in similar applications.

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Section: Digital Holography Wavefront Sensormentioning

confidence: 99%

Studies of local shock effects on Shack-Hartmann and digital holography wavefront sensors

Chu,

Bukowski,

Gordeyev

2023

Unconventional Imaging, Sensing, and Adaptive Optics 2023

View full text Add to dashboard Cite

show abstract

“…The SHWFS does not need a strong illumination source, nor does it need the long coherence length of other wavefront sensing techniques such as digital holography. 11 Wavefront reconstruction can be performed by a single matrix inversion, 7 where only the slope measurements are needed. The ease of setup allows the SHWFS to be utilized in various wavefront-based imaging applications previously mentioned.…”

Section: Introductionmentioning

confidence: 99%

Shack-Hartmann wavefront reconstruction by deep learning neural network for adaptive optics

Noel,

Bukowski,

Gordeyev

et al. 2023

Unconventional Imaging, Sensing, and Adaptive Optics 2023

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Standard methods of Shack-Hartmann wavefront reconstruction rely on solving a system of linear equations, extracting wavefront estimates from measured wavefront slopes, which are calculated by retrieving centroids from a Shack-Hartmann Wavefront Sensor (SHWFS). As the dimensions of a micro-lens array in the SHWFS increase, the computational cost of processing wavefronts can become increasingly expensive. For applications that require rapid and accurate computations, such as closed-loop adaptive-optic systems, traditional centroiding and the least-squares reconstruction becomes the main bottleneck limiting performance. In this work, we apply a convolutional neural network (CNN) approach to directly reconstruct wavefronts from raw SHWFS measurements, circumventing both bottlenecks. The CNN model utilizes the ResU-Net framework to perform a zonal wavefront reconstruction, and a method for preprocessing the raw data was investigated with the prospect of enhancing the accuracy of this model specifically for the zonal approach to wavefront reconstruction.

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Influence of cooling film pressure on the imaging quality of a hypersonic optical dome

Zhao

Ding

2020

Opt. Eng.

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Digital holography wavefront sensing with a supersonic wind tunnel

Cited by 4 publications

References 6 publications

Studies of local shock effects on Shack-Hartmann and digital holography wavefront sensors

Studies of local shock effects on Shack-Hartmann and digital holography wavefront sensors

Shack-Hartmann wavefront reconstruction by deep learning neural network for adaptive optics

Influence of cooling film pressure on the imaging quality of a hypersonic optical dome

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