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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Compromise solutions for design and technology of Fresnel lenses as sunlight concentrators
摘要： In the paper, the approaches to the Fresnel lens design in a rectilinear (“classical”) and a curvilinear (“aspherical”) refracting profile versions are discussed regarding silicone-on-glass and 3D printing technology. The advantages of short-focus lenses with an increased Fresnel profile pitch are shown. The mathematical model used for concentrating solar radiation based on direct tracking of rays has made it possible to solve the problems of designing the concentrators and comparing their characteristics with due account for limitations of the manufacturing methods used and the Fresnel lens shape errors arising from manufacturing. Optimized design parameters of Fresnel lenses based on silicone (Wacker 604) and thermoplastic (Luxexcel Opticlear) materials are presented.
关键词： optical efficiency,silicone-on-glass,chromatic aberration,Fresnel lenses,sunlight concentrators,3D printing
更新于2025-09-11 14:15:04
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Plasmonic Lenses for Tunable Ultrafast Electron Emitters at the Nanoscale
摘要： Simultaneous spatiotemporal con?nement of energetic electron pulses to femtosecond and nanometer scales is a topic of great interest in the scienti?c community, given the potential impact of such developments across a wide spectrum of scienti?c and industrial applications. For example, in ultrafast electron scattering, nanoscale probes would enable accurate maps of structural dynamics in materials with nanoscale heterogeneity, thereby leading to an understanding of the role of boundaries and defects on macroscopic properties. On the other hand, advances in this ?eld are mostly limited by the brightness and size of the electron source. We present the design, fabrication, and optical characterization of bullseye plasmonic lenses for next-generation ultrafast electron sources. Using electromagnetic simulations, we examine how the interplay between light-plasmon coupling, plasmon propagation, dispersion, and resonance governs the properties of the photoemitted electron pulse. We also illustrate how the pulse duration and strength can be tuned by geometric design and predict that sub-10-fs pulses with nanoscale diameter can be achieved. We then fabricate lenses in gold ?lms and characterize their plasmonic properties using cathodoluminescence spectromicroscopy, demonstrating suitable plasmonic behavior for ultrafast nanoscale photoemission.
关键词： plasmonic lenses,cathodoluminescence spectromicroscopy,nanoscale,ultrafast electron emitters
更新于2025-09-11 14:15:04
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High-Sensitivity AGN Polarimetry at Sub-Millimeter Wavelengths
摘要： The innermost regions of radio loud Active Galactic Nuclei (AGN) jets are heavily affected by synchrotron self-absorption, due to the strong magnetic ?elds and high particle densities in these extreme zones. The only way to overcome this absorption is to observe at sub-millimeter wavelengths, although polarimetric observations at such frequencies have so far been limited by sensitivity and calibration accuracy. However, new generation instruments such as the Atacama Large mm/sub-mm Array (ALMA) overcome these limitations and are starting to deliver revolutionary results in the observational studies of AGN polarimetry. Here we present an overview of our state-of-the-art interferometric mm/sub-mm polarization observations of AGN jets with ALMA (in particular, the gravitationally-lensed sources PKS 1830?211 and B0218+359), which allow us to probe the magneto-ionic conditions at the regions closest to the central black holes.
关键词： Graviational lenses,B0218+359,PKS 1830?211,Polarization,Active galactic nuclei,Interferometry
更新于2025-09-10 09:29:36
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High Resolution Binary Zone Plate in Double-Sided Configuration for Terahertz Radiation Focusing
摘要： A double-sided phase-reversal binary zone plate is numerically investigated and experimentally characterized at the frequency of 1 THz. The double-sided zone plate has a novel design based on a binary phase-reversal zone plate, in which the total zone thickness is split in two halves located at a distance optimized by means of numerical simulations. The samples are fabricated by a three-axis milling technique on slabs of an ultralow-loss cyclo-olefin polymer. The lenses’ characterization at the frequency of 1 THz is performed by means of a THz time-domain spectrometer, in terms of both focal length and spatial resolution. The focusing properties of the double-sided zone plate are compared with those of a conventional binary zone plate. The double-sided zone plate features 2.4 times smaller focal spot, 1.25 times higher focusing efficiency, and an approximately 10λ0 longer depth of field than the conventional binary configuration.
关键词： knife-edge technique,time-domain spectrometer,terahertz radiation,Diffractive lenses
更新于2025-09-10 09:29:36
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Terahertz imaging for multiple reflectors using time-domain correlating synthesis method
摘要： We had proposed a correlating synthesis method for terahertz imaging using a pulse reflection mode terahertz time-domain spectrometry system. The efficiency of the method for improving the resolution and eliminating fake images was verified by numerical simulations and experiments with two metal cylinders. However, an artifact image between the two reflectors is markedly shown. Moreover, the multi-reflection and the influence of echo distortion caused by the directivity of the terahertz beam have not been discussed. For application of imaging complicated target, this paper addresses following issues: 1) multi-reflection between reflectors, as well as the effect of the direction of polarization of terahertz wave; 2) distortion of echo signals from targets distributed in a broader area, as well as the effect of concave lenses. Finally, the efficiencies of these proposals are verified by an imaging experiment with five metal cylinders.
关键词： multi-reflection,concave lenses,time-domain correlating synthesis method,polarization,terahertz imaging
更新于2025-09-10 09:29:36
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Erufosine Coated Hydrophilic Intraocular Lenses Attenuate PCO Formation in Vitro
摘要： Purpose: To assess the impact of laminin and collagen IV on the proliferation of human lens epithelial cells (LECs) and the performance of two hydrophilic and one hydrophilic IOL with a hydrophobic surface coated with erufosine on their properties to inhibit LEC proliferation and migration in a well-established in vitro anterior chamber model of PCO. Setting: Research Laboratory for Experimental Ophthalmology, Ludwig-Maximilians-University, Munich, Germany. Design: Experimental study. Methods: Three IOLs were selected after pre-evaluation for their properties to inhibit LEC proliferation in vitro. All three IOLs were then coated with erufosine while uncoated IOLs of the same type and lot served as controls. Twelve well cell culture inserts were coated with either laminin or collagen IV and erufosine coated or uncoated IOLs were placed on these inserts into the wells. The wells were inserted into 12 well plates and kept under standard cell culture conditions for 6 days. After removal of the IOLs, the cell culture inserts were analyzed for LEC proliferation and migration. Conclusions: Collagen IV has a stronger impact on LEC proliferation in vitro than laminin has. All tested erufosine coated IOLs were able to significantly decrease the formation of PCO in an in vitro anterior chamber model.
关键词： Erufosine,Cataract surgery,Intraocular lenses
更新于2025-09-10 09:29:36
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Evaluation of life quality of patients submitted to cataract surgery with implants of monofocal, bifocal and multifocal lenses
摘要： Purpose: Providing an objective and subjective evaluation of life quality and satisfaction level of the patients who underwent cataract surgery with implant of bifocal, multifocal and monofocal lenses. Methods: Bifocal lenses were implanted in 72 patients, aspheric multifocal lenses in 16 patients, apodized multifocal lenses in 20 patients and Monofocal lenses were implanted in 63 patients. The patients answered a 47 question questionnaire, whose results were evaluated and analyzed. Results: The level of satisfaction of the patients implanted with bifocal and multifocal lenses was significantly higher than of those with monofocal lenses (kruskal – Wallis test, p< 0.001 followed by the Dunn test, p< 0.05). As to the comparison of monofocal lenses with bifocal and multifocal lenses, the near vision without correction was considerably lower in patients with monofocal lenses (Z test p< 0.001). The patients with monofocal lenses without correction presented a much lower capacity of reading newspapers or books and as far as manual work than the ones with bifocal and multifocal lenses (Z test, p<0.001). Conclusion: The result of this study shows that the patients who received the bifocal and multifocal lenses had a remarkable improvement in their visual acuity for the near vision, being pleased with their general vision without wearing glasses. This is because they were able to read books and newspapers, write checks, fill out forms, do sports, shave or put on make-up, hence having high quality of life without correction.
关键词： Life quality,Questionnaires,Cataract extraction,Intraocular lenses
更新于2025-09-10 09:29:36
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The effect of the optical design of multifocal contact lenses on choroidal thickness
摘要： Studies have found reduced myopia progression with multifocal contact lenses, albeit with an unclear mechanism behind their protective effect. It is hypothesized that the induced myopic defocus of the addition zones of the multifocal contact lenses leads to choroidal thickening and therefore inhibits eye growth. In the current study, the effect of the optical design of multifocal contact lenses on choroidal thickness was investigated. Eighteen myopic participants wore four different contact lenses ((1) single-vision lenses corrected for distance, (2) single-vision lenses with +2.50 D full-field defocus, (3) Multifocal center-distance design, (4) Multifocal center-near design, both with addition power +2.50 D) for 30 min each on their right eye. Automated analysis of the macular choroidal thickness and vitreous chamber depth were performed before and after the wear of each of the contact lenses. Peripheral refraction profiles in primary gaze were obtained using eccentric photorefraction prior to contact lens wear. Choroidal thickness and vitreous chamber depth showed no significant differences to baseline with any of the contact lenses (all p > 0.05). Choroidal thickness increased by +2.1 ± 11.1 μm with the Multifocal center-distance design, by +2.0 ± 11.1 μm with the full-field defocus lens, followed by the Multifocal center-near design with +1.6 ± 11.3 μm and the single-vision contact lens correcting for distance with +0.9 ± 11.2 μm. Multifocal contact lenses have no significant influence on choroidal thickness after short-term wear. Therefore, changes in choroidal thickness might not be the main contributor to the protective effect of multifocal contact lenses in myopia control.
关键词： multifocal contact lenses,choroidal thickness,optical design,defocus,myopia control
更新于2025-09-10 09:29:36
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Biomaterials and Regenerative Medicine in Ophthalmology || An introduction to ophthalmic biomaterials and their role in tissue engineering and regenerative medicine
摘要： The ultimate goal of the research and development of materials (other than drugs) for applications in medicine, which we call biomaterials, has always been to emulate natural materials. Since the natural target for biomaterials, ie, our body’s tissues and organs, is exceedingly complex, it is not surprising that in many instances the laboratory-made materials cannot match in their performance the natural entities they are meant to augment or replace. This is obviously different from the development of materials for industrial applications, which usually perform better than their natural counterparts (if the latter exist), and also evolve relatively fast, unhindered by the biological constraints inherent to living systems. For too long, an acceptable end performance in the short term was the main requirement from a biomaterial, with little attention paid to changing its bulk and/or surface properties through the manipulation of composition and/or structure, in order to maximize the clinical outcome. Over the past six decades or so, however, the progress in bringing the properties and functionality of biomaterials close to those of their biological targets has been remarkable. While the previous statements are valid for the ophthalmic biomaterials too, their development has shown some particular features. The general developments in the field of biomaterials have customarily been gauged through the achievements in the branches of orthopaedic biomaterials and, to a lesser extent, biomaterials for cardiology or dentistry, while the progress of biomaterials for the eye has usually been ignored or seldom presented.
关键词： ophthalmic biomaterials,artificial cornea,poly(methyl methacrylate),contact lenses,hydrogels,cornea,regenerative medicine,tissue engineering
更新于2025-09-10 09:29:36
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The Eye as a Window to Health: Albeit Slow, Research is Progressing on Contact Lenses for Medical Diagnostics
摘要： The idea is a compelling one: a device that looks and feels like an ordinary contact lens but that can continuously monitor a variety of health indicators. For a diabetic, such a lens might update blood glucose levels and, using a built-in flashing LED indicator light, signal when a condition needs attention. Diabetic patients might be saved from the need for repeated finger prick tests and could be monitored for longer periods of time and for a greater variety of parameters at once.
关键词： contact lenses,health monitoring,glucose monitoring,diabetes,medical diagnostics
更新于2025-09-10 09:29:36