Read by QxMD icon Read


Weixuan Zhang, Kaiyang Cheng, Chao Wu, Yi Wang, Hongqiang Li, Xiangdong Zhang
Metamaterials, artificially structured electromagnetic (EM) materials, have enabled the realization of many unconventional EM properties not found in nature, such as negative refractive index, magnetic response, invisibility cloaking, and so on. Based on these man-made materials with novel EM properties, various devices are designed and realized. However, quantum analog devices based on metamaterials have not been achieved so far. Here, metamaterials are designed and printed to perform quantum search algorithm...
November 17, 2017: Advanced Materials
André Klauss, Florian Conrad, Carsten Hille
The use of binary phase patterns to improve the integration and optimization of spatial light modulators (SLM) in an imaging system, especially a confocal microscope, is proposed and demonstrated. The phase masks were designed to create point spread functions (PSF), which exhibit specific sensitivity to major disturbances in the optical system. This allows direct evaluation of misalignment and fundamental aberration modes by simple visual inspection of the focal intensity distribution or by monitoring the central intensity of the PSF...
November 16, 2017: Scientific Reports
Clàudia Garrido, Genís Cardona, Josep L Güell, Jaume Pujol
PURPOSE: A single-center, cross-sectional study was designed to assess and compare objective and subjective quality of vision of patients intervened with penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK). METHODS: Forty-six patients previously intervened with PK (22 eyes), DALK (7 eyes) and DMEK (17 eyes) were recruited. Visual evaluation included spherical and cylindrical refraction, distance corrected visual acuity (DCVA), photopic contrast sensitivity (CS), optical quality, measured with the HD Analyzer (objective scattering index [OSI], MTF cut-off and Strehl ratio), and ocular and corneal aberrometry, measured with the KR-1W Wavefront Analyzer...
November 13, 2017: Journal of Optometry
X J Xing, H Song, X Tang
Objective: To investigate the distribution of anterior corneal high-order aberrations (HOAs) in Chinese eyes with cataract and their correlations with age and axial length for the choice of aspheric intraocular lens. Methods: Retrospective study. Six hundred twenty-five Chinese patients with cataract[male: 260, female: 365, age: (71.2±8.0) years] were categorized into 4 groups in accordance with their axial lengths. Anterior corneal HOAs in the central 6- mm zone was measured with an iTrace wavefront analyzer...
November 11, 2017: [Zhonghua Yan Ke za Zhi] Chinese Journal of Ophthalmology
Moran Rubin, Gili Dardikman, Simcha K Mirsky, Nir A Turko, Natan T Shaked
We present a new holographic concept, named six-pack holography (6PH), in which we compress six off-axis holograms into a single multiplexed off-axis hologram without loss of magnification or resolution. The multiplexed hologram contains straight off-axis fringes with six different orientations, and can be generated optically or digitally. We show that since the six different complex wavefronts do not overlap in the spatial frequency domain, they can be fully reconstructed. 6PH allows more than 50% improvement in the spatial bandwidth consumption when compared to the best multiplexing method proposed so far...
November 15, 2017: Optics Letters
Xiaofeng Weng, Tengfei Li, Zheqiang Zhong, Bin Zhang
In the radial smoothing (RS) scheme, small-scale self-focusing (SSSF) can degrade beam quality of a pump beam with a Gaussian pulse train, resulting in the degradation of the smoothing performance of the RS scheme. Considering SSSF of the pump beam in an optical Kerr medium (OKM), the propagation model of the laser beam in the RS scheme has been developed, and the effects of the characteristics of the pump beam and the thickness of the optical Kerr medium on the RS performance have further been numerically simulated and analyzed...
November 10, 2017: Applied Optics
Peiguang Zhang, Chengliang Yang, Zihao Xu, Zhaoliang Cao, Quanquan Mu, Li Xuan
We investigate a specific diversity phase for phase diversity (PD) phase retrieval, which possesses higher accuracy than common PD, especially for large-scale and high-frequency wavefront sensing. The commonly used PD algorithm employs the image intensities of the focused plane and one defocused plane to build the error metric. Unlike the commonly used PD, we explore a bisymmetric defocuses diversity phase, which employs the image intensities of two symmetrical defocused planes to build the error metric. This kind of diversity phase, named PD-BD (bisymmetric defocuses phase diversity), is analysed with the Cramer-Rao lower bound (CRLB)...
November 10, 2017: Scientific Reports
Cheng-Zhe Wu, Hua Jin, Zhen-Nv Shen, Ying-Jun Li, Xun Cui
To investigate wavefront aberrations in the entire eye and in the internal optics (lens) and retinal image qualities according to different lenticular opacity types and densities. Forty-one eyes with nuclear cataract, 33 eyes with cortical cataract, and 29 eyes with posterior subcapsular cataract were examined. In each group, wavefront aberrations in the entire eye and in the internal optics and retinal image quality were measured using a raytracing aberrometer. Eyes with cortical cataracts showed significantly higher coma-like aberrations compared to the other two groups in both entire eye and internal optic aberrations (P = 0...
November 10, 2017: Scientific Reports
Y Yao, X He, C Liu, Jianqiang Zhu
A new coded splitting imaging technique is proposed to reconstruct the complex amplitude of a light field iteratively using a single-shot measurement. In this technique, a specially designed coded splitting plate is adopted to diffract the illuminating beam into multiple beams of different orders and code their wavefronts independently and differently. From the diffraction pattern array recorded on the detector plane, both the modulus and phase distributions of the illuminating beam can be reconstructed iteratively using known transmission functions of different orders of the coded splitting plate...
November 10, 2017: Journal of Microscopy
Andreia M Rosa, Ângela C Miranda, Miguel M Patrício, Colm McAlinden, Fátima L Silva, Miguel Castelo-Branco, Joaquim N Murta
PURPOSE: To evaluate the use of functional magnetic resonance imaging (MRI) to assess neuroadaptation to multifocal intraocular lenses (IOLs). SETTING: Faculty of Medicine, University of Coimbra, Coimbra, Portugal. DESIGN: Prospective case study. METHODS: Patients with bilateral diffractive IOL implantation after cataract surgery had functional MRI at postoperative intervals of 3 weeks and 6 months. A nonintervention control group was included as proof of concept...
October 2017: Journal of Cataract and Refractive Surgery
Maria Vinas, Ana Gonzalez-Ramos, Carlos Dorronsoro, Vyas Akondi, Nuria Garzon, Francisco Poyales, Susana Marcos
PURPOSE: To measure the longitudinal chromatic aberration (LCA) by both psychophysical methods and in vivo double-pass retinal imaging in patients bilaterally implanted with trifocal diffractive intraocular lenses (IOLs). METHODS: Measurements were performed with a polychromatic adaptive optics system provided with a supercontinuum laser, a Hartmann-Shack wavefront sensor, a deformable mirror, a motorized Badal system, a pupil monitoring system, a double-pass retinal imaging channel, and a psychophysical channel with monochromatically illuminated stimuli...
November 1, 2017: Journal of Refractive Surgery
Avi Karsenty, Eitan Novoselski, Ariel Yifrach, Emmanuel Lanzmann, Yoel Arieli
Phase measurements obtained by high-coherence interferometry are restricted by the 2π ambiguity, to height differences smaller than λ/2. A further restriction in most interferometric systems is for focusing the system on the measured object. We present two methods that overcome these restrictions. In the first method, different segments of a measured wavefront are digitally propagated and focused locally after measurement. The divergent distances, by which the diverse segments of the wavefront are propagated in order to achieve a focused image, provide enough information so as to resolve the 2π ambiguity...
2017: Scanning
Mateusz Jaskulski, Andreí Martínez-Finkelshtein, Norberto López-Gil
Purpose: To develop an objective refraction formula based on the ocular wavefront error (WFE) expressed in terms of Zernike coefficients and pupil radius, which would be an accurate predictor of subjective spherical equivalent (SE) for different pupil sizes. Methods: A sphere is fitted to the ocular wavefront at the center and at a variable distance, t. The optimal fitting distance, topt, is obtained empirically from a dataset of 308 eyes as a function of objective refraction pupil radius, r0, and used to define the formula of a new wavefront refraction metric (MTR)...
2017: Journal of Ophthalmology
Bilian Ke, Xinjie Mao, Hong Jiang, Jichang He, Che Liu, Min Li, Ying Yuan, Jianhua Wang
Purpose: This study investigated the anterior ocular anatomic origin of high-order aberration (HOA) components using optical coherence tomography and a Shack-Hartmann wavefront sensor. Methods: A customized system was built to simultaneously capture images of ocular wavefront aberrations and anterior ocular biometry. Relaxed, 2-diopter (D) and 4-D accommodative states were repeatedly measured in 30 young subjects. Custom software was used to correct optical distortions and measure biometric parameters from the images...
November 1, 2017: Investigative Ophthalmology & Visual Science
Felipe Orduña-Bustamante, Pablo Luis Rendón, Erika Martínez-Montejo
A progressive spherical or spheroidal wavefront approximation has previously been found to be a necessary step for a more accurate application of Webster's wave equation to rapidly flaring horns. This leads to a necessary transformation of the horn area function, from the usual flat cross-sectional area in terms of the axial coordinate, into a curved cap-like wavefront area as a function of either the axial coordinate, the arc-length coordinate along the horn profile, the leading curved wavefront coordinate, or still other possible longitudinal coordinates...
October 2017: Journal of the Acoustical Society of America
Jian Xu, Haowen Ruan, Yan Liu, Haojiang Zhou, Changhuei Yang
Focusing light through scattering media has broad applications in optical imaging, manipulation and therapy. The contrast of the focus can be quantified by peak-to-background intensity ratio (PBR). Here, we theoretically and numerically show that by using a transmission matrix inversion method to achieve focusing, within a limited field of view and under a low noise condition in transmission matrix measurements, the PBR of the focus can be higher than that achieved by conventional methods such as optical phase conjugation or feedback-based wavefront shaping...
October 30, 2017: Optics Express
Virendra N Mahajan, Eva Acosta
This publisher's note corrects two text errors in J. Opt. Soc. Am. A34, 1908 (2017)JOAOD60740-323210.1364/JOSAA.34.001908.
November 1, 2017: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Zhaoyang Li, Takashi Kurita, Noriaki Miyanaga
Zigzag and non-zigzag beam waist shifts in a multiple-pass zigzag slab amplifier are investigated based on the propagation of a Gaussian beam. Different incident angles in the zigzag and non-zigzag planes would introduce a direction-dependent waist-shift-difference, which distorts the beam quality in both the near- and far-fields. The theoretical model and analytical expressions of this phenomenon are presented, and intensity distributions in the two orthogonal planes are simulated and compared. A geometrical optics compensation method by a beam with 90° rotation is proposed, which not only could correct the direction-dependent waist-shift-difference but also possibly average the traditional thermally induced wavefront-distortion-difference between the horizontal and vertical beam directions...
October 20, 2017: Applied Optics
S Gasilov, A Mittone, T Dos Santos Rolo, S Polyakov, S Zholudev, S Terentyev, V Blank, A Bravin, T Baumbach
In this work a double-crystal setup is employed to study compound refractive lenses made of single-crystal diamond. The point spread function of the lens is calculated taking into account the lens transmission, the wavefront aberrations, and the ultra-small-angle broadening of the X-ray beam. It is shown that, similarly to the wavefront aberrations, the ultra-small-angle scattering effects can significantly reduce the intensity gain and increase the focal spot size. The suggested approach can be particularly useful for the characterization of refractive X-ray lenses composed of many tens of unit lenses...
November 1, 2017: Journal of Synchrotron Radiation
Yin Zhang, Yijun Feng, Junming Zhao, Tian Jiang, Bo Zhu
Controlling the terahertz wave, especially the dynamical and full control of terahertz wavefront, is highly demanded due to the increasing development of practical devices and application systems. Recently considerable efforts have been made to fill the 'terahertz gap' with the help of artificial metamaterial or metasurface incorporated with graphene material. Here, we propose a scheme to design tunable metasurface consisting of metallic patch array on a grounded polymer substrate embedded with graphene layers to electrically control the electromagnetic beam reflection at terahertz frequency...
October 26, 2017: Scientific Reports
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"