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Auto-refraction versus subjective refraction in different phakic and pseudophakic conditions:the Tehran Geriatric Eye Study(TGES)

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International Journal of Ophthalmology(English edition) 2023年第8期16卷 1309-1316页

作者： Hassan Hashemi Amir Asharlous Alireza Jamali Abolghasem Mortazavi Alireza Hashemi Mehdi Khabazkhoob Noor Research Center for Ophthalmic Epidemiology Noor Eye HospitalTehran ***Iran Noor Ophthalmology Research Center Noor Eye HospitalTehran ***Iran Rehabilitation Research Center Department of OptometrySchool of Rehabilitation SciencesIran University of Medical SciencesTehran ***Iran Department of Neurosurgery Sina HospitalTehran University of Medical SciencesTehran ***Iran Department of Basic Sciences School of Nursing and MidwiferyShahid Beheshti University of Medical SciencesTehran ***Iran

AIM:To compare the subjective refraction data with non-cycloplegic auto-refraction findings in the geriatric population above 60 years of age according to the different crystalline lens conditions.METHODS:This report is a part of the Tehran Geriatric Eye Study(TGES)that was conducted from January 2019 to January 2020 on elderly population 60 years of age and above in Tehran.The samples were selected by multistage stratified random cluster sampling.Of 3791 individual invitees,3310(response rate:87.3%)participated in this study.All study participants underwent non-cycloplegic autorefraction(auto-refractometer/keratometer Nidek ARK-510)and subjective refraction.RESULTS:Regarding the sphere,eyes with mixed cataract had the worst limits of agreement(LoA:-1.24 to 0.87)and the best agreement was related to the pseudophakic eyes(LoA:-0.83 to 0.54).The highest(0.27±0.31 D)and lowest(0.21±0.27 D)differences between the two methods regarding the cylinder power were observed in eyes with cortical cataract and normal eyes,respectively.The worst LoA between the two methods in measuring the cylinder power was related to the eyes with mixed cataract(LoA:-0.44 to 0.96).Regarding the J0(horizontal/vertical components of astigmatism),the mean values of J0 obtained by auto-refraction were tended more toward against the rule direction in all crystalline lens conditions,and the two methods had the greatest difference in cortical cataract cases(0.05±0.17 D).Regarding the J45(oblique components of astigmatism),the lowest(0±0.11 D)and highest(-0.01±0.12 D)differences were observed in normal eyes and eyes with cortical cataract,respectively.CONCLUSION:The auto-refractometer/keratometer Nidek ARK-510 results in the elderly with different phakic and pseudophakic conditions do not correspond well with subjective refraction findings.This discrepancy in spherical findings is more pronounced in individuals with mixed cataract than in other cases.

关键词： refraction subjective geriatric noncycloplegic autorefraction

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Solar-tracking methodology based on refraction-polarization in Snell's window for underwater navigation

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Chinese Journal of Aeronautics 2022年第3期35卷 380-389页

作者： Pengwei HU Jian YANG Lei GUO Xiang YU Wenshuo LI School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China Beijing Advanced Innovation Center for Big Data-Based Precision Medicine Beihang UniversityBeijing 100191China Hangzhou Innovation Institute Beihang UniversityHangzhou 310051China

Underwater navigation system is an indispensable part for autonomous underwater vehicles.Due to the indiscernibility of satellite signal,however,the underwater navigation problem is quite challenging,and a satellite-free navigation scheme should be looked for.Polarization navigation,inspired by insects’capability of autonomous homing and foraging,is an alternative solution to satellite navigation with great application potential.Underwater polarization provides an indirect sun compass to animals for orientation determination.However,it is difficult to apply terrestrial solar-tracking methodologies in underwater situations due to the refraction of polarized skylight at the air–water interface.To resolve this issue,an underwater solar-tracking algorithm is developed based on the underwater refraction-polarization pattern inside the Snell’s window.By employing Snell’s law and Fresnel refraction formula to decouple the refractive ray bending and polarization deflection,the celestial polarization pattern is obtained based on underwater measurement.To further improve the accuracy,the degree of polarization is employed as a weight factor for E-vector.A long-lasting underwater experiment was conducted to validate the effectiveness of the proposed approach,and the results showed the root-mean-square errors of solar zenith and azimuth employing this algorithm were 0.3°and 1.3°,respectively.Our experimental results show that the refraction-polarization pattern inside the Snell’s window exhibits immense potential to improve the solar-tracking accuracy for underwater navigation.

关键词： Polarization refraction Snell’s window Solar position Underwater navigation

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All-angle reflectionless negative refraction with ideal photonic Weyl metamaterials

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Light(Science & Applications) 2022年第10期11卷 2444-2450页

作者： Yachao Liu Guo Ping Wang John B.Pendry Shuang Zhang College of Electronics and Information Engineering Shenzhen University518060 ShenzhenChina School of Physics&Astronomy University of BirminghamBirmingham B152TTUK The Blackett Laboratory Department of PhysicsImperial College LondonLondon SW72AZUK Department of Physics University of Hong KongHong KongChina Department of Electrical&Electronic Engineering University of Hong KongHong KongChina

Negative refraction,an unnatural optical phenomenon in which the incident and the refracted waves reside on the same side of the surface normal,has been demonstrated with the invention of negative index media based on artificially engineered photonic structures called metamaterials.It has received wide attention due to its potential applications in imaging,nonlinear optics,and electromagnetic cloaking.However,it is highly challenging to realize negative refraction operating at all angles and with the perfect transmission.In this work,leveraging the recent development in topological photonics,we propose to realize reflection less negative refraction for all incident angles with a topological metamaterial.The proposed metamaterial possesses two Weyl points of opposite topological charges.By interfacing the metamaterial with a perfect electric conductor(PEC)or a perfect magnetic conductor(PMC),the Fermi arc connecting the two Weyl points can take the form of a half-circle possessing a positive or a negative refractive index.Importantly,due to the topological protection,there is no reflection at the interface between the PEC and PMC covered areas,leading to the observation of all-angle negative refraction without reflection at the boundary.Our work provides a new platform for manipulating the propagation of surface waves,which may find applications in the construction of integrated photonic devices.

关键词： refraction topological perfect

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refraction of extraordinary rays and ordinary rays in the Savart polariscope

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Chinese Physics B 2008年第7期17卷 2504-2508页

作者：吴俊芳张淳民张英堂刘汉臣翟学军 School of Science Xi'an Jiaotong University School of Science Xi'an Polytechnic University

The refraction of rays in the Savart polariscope is different from the isotropic medium. We have analysed and discussed the refraction of rays in the Savart polariscope on the basis of the Snell law. The refraction formulae of the extraordinary rays and ordinary rays were derived. Results obtained may provide theoretical and practical guide lines for studying, developing and engineering of polarization interference imaging spectrometer.

关键词： Savart polariscope refraction Snell law extraordinary rays ordinary rays

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Generalized laws of refraction and reflection at interfaces between different photonic artificial gauge fields

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Light(Science & Applications) 2020年第1期9卷 45-55页

作者： Moshe-Ishay Cohen Christina Jörg Yaakov Lumer Yonatan Plotnik Erik H.Waller Julian Schulz Georg von Freymann Mordechai Segev Physics Department Technion-Israel Institute of TechnologyHaifa 32000Israel Solid State Institute Technion-Israel Institute of TechnologyHaifa 32000Israel Physics Department and Research Center OPTIMAS TU Kaiserslautern67663 KaiserslauternGermany Department of Physics The Pennsylvania State UniversityState CollegePA 16802USA Fraunhofer Institute for Industrial Mathematics ITWM 67663 KaiserslauternGermany

Artificial gauge fields the control over the dynamics of uncharged particles by engineering the potential landscape such that the particles behave as if effective external fields are acting on them.Recent years have witnessed a growing interest in artificial gauge fields generated either by the geometry or by time-dependent modulation,as they have been enablers of topological phenomena and synthetic dimensions in many physical settings,e.g.,photonics,cold atoms,and acoustic waves.Here,we formulate and experimentally demonstrate the generalized laws of refraction and reflection at an interface between two regions with different artificial gauge fields.We use the symmetries in the system to obtain the generalized Snell law for such a gauge interface and solve for reflection and transmission.We identify total internal reflection(TIR)and complete transmission and demonstrate the concept in experiments.In addition,we calculate the artificial magnetic flux at the interface of two regions with different artificial gauge fields and present a method to concatenate several gauge interfaces.As an example,we propose a scheme to make a gauge imaging system-a device that can reconstruct(image)the shape of an arbitrary wavepacket launched from a certain position to a predesigned location.

关键词： gauge refraction interface

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Unidirectional Negative refraction at an Exceptional Point of Acoustic P T-Symmetric Systems

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Chinese Physics Letters 2023年第12期40卷 56-61页

作者：刘宸蓝君顾仲明祝捷 Institute of Acoustics School of Physics Science and EngineeringTongji UniversityShanghai 200092China State Key Laboratory of Acoustics Chinese Academy of SciencesBeijing 100190China College of Computer Science and Technology Nanjing Tech UniversityNanjing 211800China

We demonstrate a method to realize unidirectional negative refraction in an acoustic parity-time(P T)-symmetric system, which is composed of a pair of metasurfaces sandwiching an air gap. The pair of metasurfaces possesses loss and gain modulations. The unidirectional negative refraction, which is strictly limited to the case of incident wave imposing on the loss end of the metasurface, is demonstrated at the exception point(EP) in this P T-symmetric system, while the incidence from the other side leads to strong reflection. Based on rigorous calculations, we explicitly show the underlying mechanism of this model to achieve unidirectional wave scatterings around the EP in the parametric space. In addition, the perfect imaging of a point source in the three-dimensional space, as a signature of negative refraction, is simulated to provide a verification of our work. We envision that this work may sharpen the understanding of P T-symmetric structures and inspire more acoustic functional devices.

关键词： refraction unidirectional symmetric

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Reflection and refraction on Implicit Surfaces

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Journal of Computer Science & Technology 2006年第2期21卷 166-172页

作者：胡伟秦开怀王华维李亚峰 Department of Computer Science and Technology Tsinghua University Beijing 100084 P.R. China

Implicit surfaces are often used in computer graphics. They can be easily modeled and rendered, and many objects are composed of them in our daily life. In this paper, based on the concept of virtual objects, a novel method of real-time rendering is presented for reflection and refraction on implicit surface. The method is used to construct virtual objects from real objects quickly, and then render the virtual objects as if they were real objects except for one more step of merging their images with the real objects＇ images. Characteristics of implicit surfaces are used to compute virtual objects effectively and quickly. GPUs （Graphics Processing Units） are used to compute virtual vertices quickly and further accelerate the computing and rendering processes. As a result, realistic effects of reflections and refractions on implicit surfaces are rendered in real time.

关键词： reflection refraction implicit surface GPU

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Dynamic profile of ocular refraction in pediatric cataract patients after lens surgeries

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International Journal of Ophthalmology(English edition) 2019年第12期12卷 1839-1847页

作者： Zhen-Zhen Liu Er-Ping Long Duo-Ru Lin Lei Ye Yi-Fan Xiang Wang-Ting Li Xiao-Hang Wu Xu-Tu Zhao Xiao-Ping Liu Lan-Qin Zhao Xiu-Cheng Huang Tong-Yong Yu Hui Chen Jing-Jing Chen Ming-Xing Wu Hao-Tian Lin Wei-Rong Chen Yi-Zhi Liu State Key Laboratory of Ophthalmology Zhongshan Ophthalmic Center Sun Yat-sen University

AIM: To study the change in ocular refraction in patients with pediatric cataracts(PCs) after lens extraction. METHODS: A total of 1258 patients who were undergoing cataract extraction with/without intraocular lens(IOL)implantation were recruited during preoperative examinations between Jan 2010 and Oct 2013. Patient ages ranged from 1.5 mo to 14y. Follow-ups were conducted at1 wk, 1, and 3 mo postoperatively and every 3 mo in the first year, then 6 mo thereafter. Ocular refraction [evaluated as spherical equivalent(SE)] and yearly myopic shift(YMS)were recorded and statistically analyzed among patients with age at surgery, baseline ocular refraction, gender,postoperative time and laterality(bilateral vs unilateral). RESULTS: By Dec 31st 2015, 1172 participants had been followed for more than 2y. The median follow-up period was 3y. The critical factors affecting the ocular refraction of PC patients were baseline ocular refraction, postoperative time for both aphakic and pseudophakic eyes. YMS grew most rapidly in young childhood and early adolescence. CONCLUSION: After lens surgeries, ocular refraction in PC patients shows an individual difference of change.Further concerns should be raising to monitor the rapid myopic shift at early adolescence of these patients.

关键词： pediatric cataract refraction intraocular lens myopic shift

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All-dielectric three-element transmissive Huygens’ metasurface performing anomalous refraction

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Photonics Research 2019年第12期7卷 1501-1510页

作者： CHANG LIU LEI CHEN TIESHENG WU YUMIN LIU JING LI YU WANG ZHONGYUAN YU HAN YE LI YU State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and TelecommunicationsBeijing 100876 China2Guangxi Key Laboratory of Wireless Wideband Communication and Signal Processing Guilin 541004 China3College of Optical Sciences The University of ArizonaTucsonArizona 85721USA

Metasurfaces have pioneered a new avenue for advanced wave-front engineering.Among the various types of metasurfaces,Huygens'metasurfaces are thought to be a novel paradigm for flat optical devices.Enabled by spectrally overlapped electric resonance and magnetic resonance,Huygens'metasurfaces are imparted with high transmission and full phase coverage of 2π,which makes them capable of realizing high-efficiency wave-front control.However,a defect of Huygens'metasurfaces is that their phase profiles and transmissive responses are often sensitive to the interaction of neighboring Huygens'elements.Consequently,the original assigned phase distribution can be distorted.In this work,we present our design strategy of transmissive Huygens'metasurfaces performing anomalous refraction.We illustrate the investigation of Huygens'elements,realizing the overlapping between an electric dipole and magnetic dipole resonance based on cross-shaped structures.We find that the traditional discrete equidistant-phase design method is not enough to realize a transmissive Huygens'surface due to the interaction between neighboring Huygens'elements.Therefore,we introduce an extra optimization process on the element spacing to palliate the phase distortion resulting from the element interaction.Based on this method,we successfully design unequally spaced three-element transmissive metasurfaces exhibiting anomalous refraction effect.The anomalous refractive angle of the designed Huygens'metasurface is 30°,which exceeds the angles of most present transmissive Huygens'metasurfaces.A transmissive efficiency of 83.5%is numerically derived at the operating wavelength.The far-field electric distribution shows that about 93%of transmissive light is directed along the 30°refractive direction.The deflection angle can be tuned by adjusting the number of Huygens'elements in one metasurface unit cell.The design strategies used in this paper can be inspiring for other functional Huygens'metasurface schemes.

关键词： interaction. element refraction

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Negative refraction in a rotational plasma metamaterial

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Plasma Science and Technology 2019年第1期21卷 13-18页

作者：詹烨旻郭斌 Department of Physics Wuhan University of Technology

The features of negative refraction are investigated by using a rotational plasma metamaterial. It is assumed that the plasma metamaterial is composed of plasma and dielectric material periodically. The analytical results show that the plasma density, plasma filling factor, and rotation angle significantly changed the properties of negative refraction. Interestingly, the plasma metamaterial without exhibiting negative refraction effect will show negative refraction when rotating the optical axis of the metamaterial, while the range of incident angle for negative refraction will be reduced or even disappear for the plasma metamaterial exhibiting negative refraction effect when rotating the optical axis. Moreover, the full-angle negative refraction can be obtained by specific rotation angle and plasma density. The effects of plasma density, plasma filling factor and the rotation angle on the properties of THE negative refraction effect are also explored and discussed in detail.

关键词： negative refraction plasma metamaterial Poynting vector rotational

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