Search results for "Diffractive"
showing 10 items of 30 documents
Multiple-plane image formation by Walsh zone plates.
2018
[EN] A radial Walsh filter is a phase binary diffractive optical element characterized by a set of concentric rings that take the phase values 0 or ¿, corresponding to the values + 1 or ¿1 of a given radial Walsh function. Therefore, a Walsh filter can be re-interpreted as an aperiodic multifocal zone plate, capable to produce images of multiple planes simultaneously in a single output plane of an image forming system. In this paper, we experimentally demonstrate for the first time the focusing capabilities of these structures. Additionally, we report the first achievement of images of multiple-plane objects in a single image plane with these aperiodic diffractive lenses.
Visual and optical performance with hybrid multifocal intraocular lenses
2010
During the past years, the wish to become independent of spectacles has been growing among cataract and presbyopic patients due to many factors, such as the increase in near visual demands, the aesthetic need for a spectacle-free image and ageing of refractive surgery patients, among others. This review assesses recently published studies that analyse visual and optical performance through different metrics of eyes implanted with multifocal intraocular lenses (IOLs), particularly hybrid IOL designs. The published evidence suggests that hybrid multifocal IOLs provide very good outcomes in a number of visual and optical performance parameters. Patients implanted with this type of IOL obtain a…
Working-Age Cataract Patients: Visual Results, Reading Performance, and Quality of Life with Three Diffractive Multifocal Intraocular Lenses
2013
Purpose To compare the visual outcomes, reading performance, and quality of life (QoL) of working-age cataractous patients bilaterally implanted with 3 different diffractive multifocal intraocular lenses (MIOLs). Design Two-center, randomized, prospective, double-masked study. Participants Sixty-three consecutive patients (126 eyes) seen at Ophthalmology Section, Palermo and Florence University, Italy, randomized to receive the ReSTOR SN6AD3 (Alcon Laboratories, Inc, Irvine, CA) (20 patients, group A), ReSTOR SN6AD1 (Alcon Laboratories, Inc) (21 patients, group B), or TECNIS ZMA00 (Abbott Medical Optics, Santa Ana, CA) (22 patients, group C) MIOL. Intervention Phacoemulsification. Main Outc…
Impact of lens material on objective refraction in eyes with trifocal diffractive intraocular lenses
2021
Purpose: Compare subjective (Rx) and objective (ObjRx) refractions outcomes with two autorefractors models and an aberrometer in eyes implanted with a hydrophobic trifocal IOL (FineVision POD F GF, Physiol, Liége, Belgium) and a hydrophilic one (FineVision POD F, Physiol, Liége, Belgium). Methods: Prospective comparative cohort study, with 100 subjects randomly assigned to either the POD F group (n = 50) or the POD F-GF group (n = 50). Postoperative eye examinations at 1-month visit included seven result sets, one for each assessment method: Rx, AR (automated refraction measured with the autorefractor KR8800), WF-P (Zernike-coefficients-based objective refraction, photopic pupil size), WF-M…
Wavelength tuning of femtosecond pulses generated in nonlinear crystals by using diffractive lenses
2010
We demonstrate that diffractive lenses (DLs) can be used as a simple method to tune the central wavelength of femtosecond pulses generated from second-order nonlinear optical processes in birefringent crystals. The wavelength tunability is achieved by changing the relative distance between the nonlinear crystal and the DL, which acts in a focusing configuration. Besides the many practical applications of the so-generated pulses, the proposed method might be extended to other wavelength ranges by demonstrated similar effects on other nonlinear processes, such as high-order harmonic generation.
"Decay Phase-Space Volume of Partial Waves" of "Light isovector resonances in $\pi^- p \to \pi^-\pi^-\pi^+ p$ at 190 GeV/${\it c}$"
2018
Decay phase-space volume $I_{aa}$ for the 14 selected partial waves as a function of $m_{3\pi}$, normalized such that $I_{aa}(m_{3\pi} = 2.5~\text{GeV}/c^2) = 1$. The wave index $a$ represents the quantum numbers that uniquely define the partial wave. The quantum numbers are given by the shorthand notation $J^{PC} M^\varepsilon [$isobar$] \pi L$. We use this notation to label the decay phase-space volume in the column headers. The labels are identical to the ones used in the column headers of the table of the transition amplitudes. $I_{aa}$ is calculated using Monte Carlo integration techniques for fixed $m_{3\pi}$ values, which are given in the first column, in the range from 0.5 to 2.5 Ge…
"Transition Amplitudes" of "Light isovector resonances in $\pi^- p \to \pi^-\pi^-\pi^+ p$ at 190 GeV/${\it c}$"
2018
Real and imaginary parts of the normalized transition amplitudes $\mathcal{T}_a$ of the 14 selected partial waves in the 1100 $(m_{3\pi}, t')$ cells (see Eq. (12) in the paper). The wave index $a$ represents the quantum numbers that uniquely define the partial wave. The quantum numbers are given by the shorthand notation $J^{PC} M^\varepsilon [$isobar$] \pi L$. We use this notation to label the transition amplitudes in the column headers. The $m_{3\pi}$ values that are given in the first column correspond to the bin centers. Each of the 100 $m_{3\pi}$ bins is 20 MeV/$c^2$ wide. Since the 11 $t'$ bins are non-equidistant, the lower and upper bounds of each $t'$ bin are given in the column he…
Lacunar fractal photon sieves
2007
We present a new family of diffractive lenses whose structure is based on the combination of two concepts: photon sieve and fractal zone plates with variable lacunarity. The focusing properties of different members of this family are examined. It is shown that the sieves provide a smoothing effect on the higher order foci of a conventional lacunar fractal zone plate. However, the characteristic self-similar axial response of the fractal zone plates is always preserved.
Bifractal focusing and imaging properties of Thue-Morse Zone Plates.
2015
We present a new family of Zone Plates (ZPs) designed using the Thue-Morse sequence. The focusing and imaging properties of these aperiodic diffractive lenses coined Thue-Morse Zone Plates (TMZPs) are examined. It is demonstrated that TMZPs produce a pair of self-similar and equally intense foci along the optical axis. As a consequence of this property, under broadband illumination, a TMZP produces two foci with an extended depth of focus and a strong reduction of the chromatic aberration compared with conventional periodic ZPs. This distinctive optical characteristic is experimentally confirmed.
Fractal square zone plates
2013
[EN] In this paper we present a novel family of zone plates with a fractal distribution of square zones. The focusing properties of these fractal diffractive lenses coined fractal square zone plates are analytically studied and the influence of the fractality is investigated. It is shown that under monochromatic illumination a fractal square zone plate gives rise a focal volume containing a delimited sequence of two-arms-cross pattern that are axially distributed according to the self-similarity of the lens.