Results 61 to 70 of about 65,352 (331)

Generating Artificial Reference Images for Open Loop Correlation Wavefront Sensors [PDF]

open access: yes, 2018
Shack-Hartmann wavefront sensors for both solar and laser guide star adaptive optics (with elongated spots) need to observe extended objects. Correlation techniques have been successfully employed to measure the wavefront gradient in solar adaptive optics systems and have been proposed for laser guide star systems.
arxiv   +1 more source

Optical wavefront phase-tilt measurement using Si-photonic waveguide grating couplers [PDF]

open access: yesarXiv, 2023
Silicon photonic wavefront phase-tilt sensors for wavefront monitoring using surface coupling grating arrays are demonstrated. The first design employs the intrinsic angle dependence of the grating coupling efficiency to determine local wavefront tilt, with a measured sensitivity of 7 dB/degree.
arxiv  

Atmospheric Turbulence with Kolmogorov Spectra: Software Simulation, Real-Time Reconstruction and Compensation by Means of Adaptive Optical System with Bimorph and Stacked-Actuator Deformable Mirrors

open access: yesPhotonics, 2023
Atmospheric turbulence causes refractive index fluctuations, which in turn introduce extra distortions to the wavefront of the propagated radiation. It ultimately degrades telescope resolution (in imaging applications) and reduces radiation power density
Ilya Galaktionov   +4 more
doaj   +1 more source

Rebuilding ships while at sea—Character individuality, homology, and evolutionary innovation

open access: yesJournal of Morphology, Volume 284, Issue 1, January 2023., 2023
Building on a previous account of evolutionary innovation, I propose here that evolutionary novelties are those individualized characters that are not homologous to any characters in the ancestor. Integrating functional and structural perspectives, I argue that functional as well as structural considerations are important for character ...
Gerhard Schlosser
wiley   +1 more source

Experimental Trials With The Optical Differentiation Wavefront Sensor For Extended Objects [PDF]

open access: yesarXiv, 2022
Commonly used wavefront sensors, the Shack Hartmann wavefront sensor and the pyramid wavefront sensor, for example, have large dynamic range or high sensitivity, trading one regime for the other. A new type of wavefront sensor is being developed and is currently undergoing testing at the University of Arizona's Center for Astronomical Adaptive Optics ...
arxiv  

Compressive Shack-Hartmann Wavefront Sensor based on Deep Neural Networks [PDF]

open access: yes, 2020
The Shack-Hartmann wavefront sensor is widely used to measure aberrations induced by atmospheric turbulence in adaptive optics systems. However if there exists strong atmospheric turbulence or the brightness of guide stars is low, the accuracy of wavefront measurements will be affected.
arxiv   +1 more source

An Optical Wavefront Sensor Based on a Double Layer Microlens Array

open access: yesSensors, 2011
In order to determine light aberrations, Shack-Hartmann optical wavefront sensors make use of microlens arrays (MLA) to divide the incident light into small parts and focus them onto image planes.
Hsiang-Chun Wei   +3 more
doaj   +1 more source

Wavefront Reconstruction of Shack-Hartmann with Under-Sampling of Sub-Apertures

open access: yesPhotonics, 2023
Shack-Hartmann wavefront sensor plays a key role in adaptive optics (AO) systems, which detect the aberrant wavefront by an array of micro-lenslets across the aperture pupil.
Jian Huang   +3 more
doaj   +1 more source

High Sensitivity Wavefront Sensing with a non-linear Curvature Wavefront Sensor [PDF]

open access: yes, 2009
A new wavefront sensing approach, derived from the successful curvature wavefront sensing concept but using a non-linear phase retrieval wavefront reconstruction scheme, is described. The non-linear curvature wavefront sensor (nlCWFS) approaches the theoretical sensitivity limit imposed by fundamental physics by taking full advantage of wavefront ...
arxiv   +1 more source

Wavefront sensing with a brightest pixel selection algorithm

open access: yes, 2011
Astronomical adaptive optics systems with open-loop deformable mirror control have recently come on-line. In these systems, the deformable mirror surface is not included in the wavefront sensor paths, and so changes made to the deformable mirror are not ...
A. G. Basden   +16 more
core   +2 more sources

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