Results 121 to 130 of about 4,513 (162)

Circular Mathieu and Weber autofocusing beams

Optics Letters, 2022
In this Letter, the new classes of non-paraxial autofocusing beams are introduced for the first time, to the best of our knowledge. We investigate both numerically and experimentally non-paraxial circular Mathieu and Weber autofocusing beams based on the solutions of the Helmholtz equation in elliptical and parabolic coordinates, respectively.
Yong Zhang, Zhenwu Mo, Danling Xu, Shangling He, Yiping Ding, Qiaobing Huang, Zhili Lu, Dongmei Deng   +7 more
openaire   +2 more sources

Autofocusing in digital holography

SPIE Proceedings, 2013
Digital holography allows the acquisition of 3D profiles of objects. Digitally captured holograms are reconstructed at the respective distances of the objects to reveal the phase and the intensity profiles. However, computing an object’s 3D profile with only a single reconstruction requires prior knowledge of the distance of the object from the ...
Hazar A. İlhan, Mert Doğar, Meric Özcan   +2 more
openaire   +1 more source

Autofocusing in digital holography using eigenvalues

Applied Optics, 2021
A new autofocusing algorithm for digital holography is proposed based on the eigenvalues of the images reconstructed at different distances in the measurement volume. An image quality metric evaluated based on the distribution of its eigenvalues is compared in function of the reconstruction distance to identify the location of the focal plane.
Anik, Ghosh, Rishikesh, Kulkarni, Pranab Kumar, Mondal   +2 more
openaire   +2 more sources

Aberration laser beams with autofocusing properties

Applied Optics, 2018
We investigate theoretically, numerically, and experimentally a novel type of laser beam-an aberration laser beam (ALB). To generate the ALB, a diffractive optical element with a phase transmission function having an arbitrary radial dependence of power q and a periodic angular dependence of sin(mϕ) or cos(mϕ) form can be used.
Svetlana N, Khonina, Andrey V, Ustinov, Alexey P, Porfirev   +2 more
openaire   +2 more sources

Edge-Preserving Autofocusing in Digital Holography

Digital Holography and Three-Dimensional Imaging, 2016
In digital holography, it is essential to know the axial position of the recorded object for reconstruction. Here we propose an autofocusing algorithm using structure tensor to determine the focal distance and to extract the edge information.
Ren, Z, Lam, EYM
openaire   +2 more sources

Multi-Subaperture PGA for SAR Autofocusing

IEEE Transactions on Aerospace and Electronic Systems, 2013
For spotlight mode synthetic aperture radar (SAR) autofocusing, the traditional full-aperture phase gradient autofocus (PGA) algorithm might suffer from performance degradation in the presence of significant high-order phase error and residual range cell migration (RCM), which tend to occur when the coherent processing interval (CPI) is long. Meanwhile,
Daiyin Zhu, Rui Jiang, Xinhua Mao, Zhaoda Zhu   +3 more
openaire   +1 more source

The autofocusing system of the IMAT neutron camera

Review of Scientific Instruments, 2013
In this paper, we present the autofocusing system of the imaging instrument to be used on IMAT, a new neutron-imaging facility under construction at the ISIS (UK) target station 2. We have compared 16 different autofocus algorithms to select the one with the best performance. The algorithms have been evaluated by using both a qualitative analysis and a
V Finocchiaro, F Aliotta, D Tresoldi, RC Ponterio, C S Vasi, G Salvato   +5 more
openaire   +4 more sources

Autofocusing and residual migration of SAR images

International Conference on Acoustics, Speech, and Signal Processing, 2002
A particular approach to the azimuth migration of synthetic aperture radar (SAR) data is discussed. It is shown that a slightly defocused SAR image can be corrected by means of a short monodimensional filter with a quadratic phase vs. time characteristic.
MONTI-GUARNIERI, ANDREA VIRGILIO, PRATI, CLAUDIO MARIA   +1 more
openaire   +2 more sources

Autofocusing accelerator beams

A novel tuning approach, Model Coupled Accelerator Tuning (MCAT), has been applied to the separated function DTL at TRIUMF's Isotope Separator and Accelerator (ISAC). A digital twin of the rare-isotope postaccelerator is used for transverse and longitudinal tune optimizations, which are then loaded directly into the control system.
Katrusiak,Alexander, Shelbaya,Olivier, Baartman,Rick, Kester,Oliver, Ruiz,Chris   +4 more
openaire   +2 more sources

Autofocusing optical-resolution photoacoustic endoscopy

Optics Letters, 2018
Photoacoustic (PA) endoscopy has the potential to diagnose early diseases in the gastrointestinal tract. For the first time, to our knowledge, we developed an autofocusing PA endoscope (AF-PAE) for the usually irregular gastrointestinal tract imaging to solve the deterioration of transverse resolution caused by the defocus scanning of the probe.
Kedi, Xiong, Sihua, Yang, Xiaowan, Li, Da, Xing   +3 more
openaire   +2 more sources