Results 71 to 80 of about 6,169 (204)

Review and experimental comparison of speckle‐tracking algorithms for X‐ray phase contrast imaging

Journal of Synchrotron Radiation, Volume 32, Issue 1, Page 180-199, January 2025.
This review focuses on low‐dose near‐field X‐ray speckle phase imaging in the differential mode introducing the existing algorithms with their specifications and comparing their performances under various experimental conditions.X‐ray speckles have been used in a wide range of experiments, including imaging (and tomography), wavefront sensing, spatial ...
Rafael Celestre, Laurène Quénot, Christopher Ninham, Emmanuel Brun, Luca Fardin   +4 more
wiley   +1 more source

Sources of reduced visual acuity and spectacle treatment options for individuals with Down syndrome: Review of current literature

Ophthalmic and Physiological Optics, Volume 44, Issue 7, Page 1326-1345, November 2024.
Abstract Individuals with Down syndrome are known to have a greater prevalence of ocular conditions such as strabismus, nystagmus, elevated refractive error, poor accommodative function, elevated higher‐order optical aberrations and corneal abnormalities.
Heather A. Anderson
wiley   +1 more source

On-sky multi-wavelength phasing of segmented telescopes with the Zernike phase contrast sensor

, 2011
Future Extremely Large Telescopes will adopt segmented primary mirrors with several hundreds of segments. Cophasing of the segments together is essential to reach high wavefront quality.
Cavarroc, Chanan, Chanan, Dohlen, Dohlen, Dupuy, Gilmozzi, Gonte, Houairi, Lofdahl, Martinez, Mazzoleni, Montoya-Martínez, Nelson, Pinna, Polhemus, Surdej, Wilhelm, Yaitskova, Yaitskova, Zernike   +20 more
core   +3 more sources

Coherence vortices by binary pinholes

Nanophotonics, Volume 13, Issue 24, Page 4397-4407, November 2024.
Abstract Singularity in a two‐point complex coherence function, known as coherence vortices, represents zero visibility with a helical phase structure. In this paper, we introduce a novel technique to generate the coherence vortices of different topological charges by incoherent source transmittance with exotic structured binary pinholes.
Akanksha Gautam, Amit K. Agarwal, Rakesh Kumar Singh   +2 more
wiley   +1 more source

Spectral characterization of optical aberrations in fluidic lenses

Frontiers in Physics
We report an extensive numerical study and supporting experimental results on the spectral characterization of optical aberrations in macroscopic fluidic lenses with tunable focal distance and aperture shape.
Graciana Puentes, Graciana Puentes, Fernando Minotti, Fernando Minotti   +3 more
doaj   +1 more source

Wavefront sensing with a brightest pixel selection algorithm

, 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, Basden, Basden, E. Gendron, Foy, Gendron, Gendron, Lardière, Marchetti, Masciadri, Myers, R. M. Myers, Roddier, Simonich, Tatarski, Thomas, Thomas   +16 more
core   +2 more sources

High‐angular‐sensitivity X‐ray phase‐contrast microtomography of soft tissue through a two‐directional beam‐tracking synchrotron set‐up

Journal of Synchrotron Radiation, Volume 31, Issue 5, Page 1293-1298, September 2024.
X‐ray phase‐contrast microtomography is demonstrated using two‐dimensional amplitude modulation of the beam. The implementation is characterised in terms of angular sensitivity and spatial resolution, and its application to the three‐dimensional imaging of biological soft tissues is shown.Two‐directional beam‐tracking (2DBT) is a method for phase ...
Carlos Navarrete-León, P. Stephen Patrick, Adam Doherty, Harry Allan, Silvia Cipiccia, Shashidhara Marathe, Kaz Wanelik, Michela Esposito, Charlotte K. Hagen, Alessandro Olivo, Marco Endrizzi   +10 more
wiley   +1 more source

Simultaneously measuring ocular aberration and anterior segment biometry during accommodation [PDF]

Journal of Innovative Optical Health Sciences, 2015
In the human eye, accommodation is essential for functional vision. However, the mechanisms regulating accommodation and the ocular parameters affecting aberrations remain to be explored.
Yuanyuan Wang, Yilei Shao, Yimin Yuan
doaj   +1 more source

Soft X‐ray wavefront sensing at an ellipsoidal mirror shell

Journal of Synchrotron Radiation, Volume 31, Issue 4, Page 690-697, July 2024.
Phase retrieval at an axisymmetric ellipsoidal mirror is demonstrated with soft X‐rays (277 eV), completed by a reconstruction of the focus as well as figure and alignment error of the mirror. Based on simple measurements of the cross‐focal, three‐dimensional intensity distribution, an intuitive algorithm is proposed which combines the advantages of ...
Christoph Braig, Jürgen Probst, Heike Löchel, Ladislav Pina, Thomas Krist, Christian Seifert   +5 more
wiley   +1 more source

Gaze and behavioural metrics in the refractive correction of presbyopia

Ophthalmic and Physiological Optics, Volume 44, Issue 4, Page 774-786, June 2024.
Abstract Purpose To investigate gaze and behavioural metrics at different viewing distances with multifocal contact lenses (MFCLs), single vision contact lenses (SVCLs) and progressive addition lenses (PALs). Methods Fifteen presbyopic contact lens wearers participated over five separate study visits.
Sarah L. Smith, Carole Maldonado‐Codina, Philip B. Morgan, Michael L. Read   +3 more
wiley   +1 more source