Results 51 to 60 of about 44,477 (288)

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  

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

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

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

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

X-ray wavefront characterization with two-dimensional wavefront sensors: shearing interferometers and Hartmann wavefront sensors [PDF]

open access: yesSPIE Proceedings, 2012
Phase reconstructions from a two-dimensional shearing inter- ferometer, based on two orthogonal phase gratings in a single plane, and a Hartmann sensor are compared. Design alternatives for both wavefront sensors are given, and simulated performance of both the two-dimen- sional x-ray shearing interferometer and Hartmann wavefront sensor are presented ...
openaire   +4 more sources

Omnidirectional Transmissive Acoustic Metasurfaces Based on Goldberg Polyhedra

open access: yesAdvanced Functional Materials, EarlyView.
This study introduces omnidirectional acoustic metasurfaces capable of manipulating wavefronts in multiple arbitrary directions simultaneously. A full‐stack pipeline for design, optimization, and fabrication is presented to construct near‐spherical holograms based on Goldberg polyhedra.
Andrea Achilleos   +3 more
wiley   +1 more source

Enhancing Ultrasound Power Transfer: Efficiency, Acoustics, and Future Directions

open access: yesAdvanced Materials, EarlyView.
Implantable devices significantly enhance healthcare but are limited by battery life. Ultrasound power transfer technology offers a promising solution for sustainable operation. This review addresses gaps in current research, particularly in sound field analysis and energy efficiency optimization.
Yi Zheng   +6 more
wiley   +1 more source

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