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- 摘要
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Advanced Operation of Microcolumn by Introducing Misalign Corrector
摘要： We introduced an advanced operation of a microcolumn to recover electron beam properties caused by electrodes misalign. The misalign corrector consists of a pair of electrodes and each electrode is divided by four even parts. We confirmed that by applying appropriate bias voltage to some parts of the corrector, electron beam trajectory could be adjusted. As a result, it is found that the corrector can be an useful electron unit to obtain fine electron beam properties.
关键词： Electron beam,Microcolumn,Einzel lens,Misalignment,Source lens
更新于2025-09-23 15:23:52
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Contact Lenses || Rigid Gas Permeable Corneal and Corneoscleral Lens Fitting
摘要： This chapter covers the fitting of rigid gas permeable (RGP) corneal and corneoscleral lenses, including materials, corneal shape, forces affecting lens fit, fluorescein patterns, fitting principles, special designs, computerized fitting, fitting routines, aftercare problems, lens care, identification of materials, ordering, prescription writing, and recording fits.
关键词： Rigid Gas Permeable,Corneoscleral Lens,Fluorescein Patterns,Materials,Fitting,Corneal Lens
更新于2025-09-23 15:23:52
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Sky camera geometric calibration using solar observations
摘要： A camera model and associated automated calibration procedure for stationary daytime sky imaging cameras is presented. The specific modeling and calibration needs are motivated by remotely deployed cameras used to forecast solar power production where cameras point skyward and use 180° fisheye lenses. Sun position in the sky and on the image plane provides a simple and automated approach to calibration; special equipment or calibration patterns are not required. Sun position in the sky is modeled using a solar position algorithm (requiring latitude, longitude, altitude and time as inputs). Sun position on the image plane is detected using a simple image processing algorithm. The performance evaluation focuses on the calibration of a camera employing a fisheye lens with an equisolid angle projection, but the camera model is general enough to treat most fixed focal length, central, dioptric camera systems with a photo objective lens. Calibration errors scale with the noise level of the sun position measurement in the image plane, but the calibration is robust across a large range of noise in the sun position. Calibration performance on clear days ranged from 0.94 to 1.24 pixels root mean square error.
关键词： fisheye lens,geometric calibration,camera model,sky camera,solar observations,solar power forecasting
更新于2025-09-23 15:23:52
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Matrix Metalloproteinase-Deactivating Contact Lens for Corneal Melting
摘要： Corneal melting is an uncontrolled, excessive degradation of cellular and extracellular components of the cornea. This potential cause of corneal blindness is caused by excessive expression of zinc-dependent matrix metalloproteinases (MMPs) and has no satisfying cure as of now. Herein, we introduce a novel therapeutic hydrogel which can be made into a contact lens to slow down the progression of corneal melting by deactivating MMPs. The hydrogel backbone is comprised of poly(2-hydroxyetyl methacrylate) (pHEMA), a main material for commercial contact lenses, and dipicolylamine (DPA) which has high affinity and selectivity towards zinc ion. Due to the high affinity towards zinc ions, the DPA-conjugated pHEMA (pDPA-HEMA) hydrogel selectively removes zinc ions from a physiological buffer and deactivates MMP-1, MMP-2 and MMP-9 within 2 hours. pDPA-HEMA hydrogel also effectively prevents degradation of porcine corneas by collagenase A, a zinc-dependent protease, whereas the corneas completely degrades within 15 hours when incubated with pHEMA hydrogel. The presence of pDPA-HEMA hydrogel does not affect the viability of keratocytes and corneal epithelial cells. Unlike the conventional MMP inhibitors (MMPi), the pDPA-HEMA hydrogel minimizes the risk of serious non-specific side effects, and provides a method to slow down the progression of corneal melting and other related ocular diseases.
关键词： dipicolylamine,contact lens,corneal melting,hydrogel,zinc,matrix metalloproteinases
更新于2025-09-23 15:23:52
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Long Term Clinical and Visual Outcomes of Retrofixated Iris Claw Lenses Implantation in Complicated Cases
摘要： Aims: To evaluate the visual outcomes and complications after implantation of retrofixated iris claw (RFIC) lens in various challenging situations. Settings and Design: Retrospective, single centre, 8 year clinical audit. Materials and Methods: A retrospective analysis of cases who underwent RFIC lens implantation alone (group 1) or in combination with vitreoretinal (VR), corneal or glaucoma procedures (group 2) was performed. The main outcomes evaluated were corrected distant visual acuity (CDVA) and postoperative complications. The mean follow up was 13.09±6.8 (range 6-24) months. Results: The study involved 100 eyes of 83 patients with mean age of 51.1±25.4 years. Group 1 included 59 eyes and group 2 had 41 eyes. In group 1, the mean CDVA improved from 0.86±0.81 to 0.38±0.51 LogMAR (p<0.001) with 72.8% eyes having gain in lines (≥ 2 lines) of CDVA with safety index of 1.73. The mean CDVA in group 2 improved from 0.71±0.65 to 0.38±0.34 LogMAR (p=0.003) with 65.8% eyes having gain in lines (≥ 2 lines) of CDVA with a safety index of 1.54. Group 2 showed a higher complication rate of 36.59% compared to group 1 (20.34%). Significant complications noted were secondary glaucoma (8%), disenclavation of haptic (4%), subluxation of RFIC lens (1%). Conclusion: The visual outcome with RFIC lenses when combined with other intraocular procedures is mainly affected by the complexity of co-existing pathologies .The complications are more related to the combined procedures performed rather than RFIC lens implantation alone. This may still be acceptable when complication profile of other intraocular lenses is evaluated in similar challenging situations.
关键词： iris claw,enclavation,vitreoretinal,Combined,intraocular lens,retrofixated
更新于2025-09-23 15:23:52
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Rotated infrared antenna transmitarray for the manipulation of circularly polarized wavefronts
摘要： An IR optical transmitarray is presented based on Antenna Array Sheet (AAS) for the manipulation of circularly polarized light. The unit cell of the transmitarray comprises three layers of metallic elliptical patches. Complete phase control is achieved through the local rotation of each unit cell. Thin refraction and focusing transmitarrays of this sort are demonstrated at infrared frequencies. Moreover, a new concept for realizing a polarization-discriminating device is introduced based on a flat refracting lens. These devices are compatible with current fabrication technology and can become crucial for the integration with other IR and nano-photonic devices.
关键词： Metasurfaces,Transmitarrays,Polarization discrimination,Infrared lens,Circular polarization
更新于2025-09-23 15:23:52
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Incidence of posterior capsular opacification requiring Nd:YAG capsulotomy after cataract surgery and implantation of enVista? MX60 IOL
摘要： Purpose. — To evaluate incidence of posterior capsule opacification requiring Nd:YAG capsulotomy over 3 years in a large series of eyes implanted with the enVista? MX60 Intraocular Lens (IOL). Methods. — A university-based, single-center, observational study of patients’ medical records was conducted. Uneventful cataract surgery patients with in-the-bag implantations of the enVista? MX60 IOL with a minimum of 24 months follow-up were included in the study. Exclusion criteria were insufficient follow-up (< 24 months), intraoperative complications and combined surgery. The primary outcome measure was rate of YAG laser capsulotomy, while secondary outcome measures were time to YAG laser capsulotomy and rate of glistenings. Results. — A total of 245 eyes of 143 patients received the MX60 IOL and were followed in the same center. Of these, 226 eyes were included in the study. Mean age was 80.7 ± 8.3 years and M/F ratio was 42/101 (29.4/70.6%). The mean preoperative distance (logMAR) visual acuity was 0.67 ± 0.5, while postoperatively it was 0.31 ± 0.5 at the last visit. The Mean follow-up time (min-max) was 35.2 ± 7.2, (24—48.4) months. The incidence of Nd:YAG capsulotomy over 3 years was 5/226 (2.2%). Average time between surgery and Nd:YAG capsulotomy was 32.17 months. Univariate analysis of age, gender, presence of comorbidity and baseline visual acuity found no predictive factors for capsulotomy. No glistenings were reported at any postoperative visit. Conclusion. — The three-year cumulative incidence of PCO requiring Nd:YAG laser capsulotomy was 2.2% for the enVista? MX-60 IOL, with no glistenings observed during follow-up. This low rate confirms the excellent safety profile of this IOL.
关键词： Cataract surgery,Intraocular lens,Posterior capsule opacification,MX60,Glistening
更新于2025-09-23 15:23:52
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[Advances in Imaging and Electron Physics] || superconductors and magnetic electron lenses
摘要： The use of superconductors seems a logical step if one wants to make iron-free magnetic lenses or to reduce the dimensions of conventional lenses since, when decreasing the coil size, the current density is increased. In the 1960s and 1970s, research mainly concentrated on the applicability of superconductors to magnetic electron lenses, and took place on a relatively large scale. This is reviewed in Section 2, after a general introduction into superconductivity in Section 1. Superconducting lenses and microscopes did not become popular due to their inconvenient operation and the lack of interest in high-voltage electron microscopy. High-voltage microscopy has been one of the main reasons for working on strong magnetic lenses and, consequently, on the utilization of superconductors. In 1986, with the discovery of high-temperature superconductivity, discussion on the applicability of superconductors to magnetic electron lenses was reopened. In the past, one of the most serious disadvantages in operating superconducting lenses had been related to the use of liquid helium refrigeration, so high-T c superconductors might be employed to overcome this problem, because their cooling demands are much more relaxed. However, especially during the first years of high-Tc superconductivity, despite their high operating temperatures, the materials themselves seemed extremely unfriendly, as they were brittle, sensitive to water, unstable, and difficult to produce. Fortunately, most of these disadvantages have now disappeared and the discussion concerning their utilization assumes a more fundamental character in the sense that most of the properties of the high-Tc materials are known, though a sound theoretical basis has not yet been defined. The properties of high-T c superconductors are the subject of Section 3. The question whether high-Tc superconductors are more appropriate for applications in particle optics than their classical counterparts was considered to be an interesting research topic. Therefore, this work was started as a feasibility study to the use of high-temperature superconductors in particle optics. Most short-term applications in this field were expected to exploit the high current density of these materials at temperatures above liquid helium, so this work concentrated on magnetic lenses as one of the most straightforward high current density applications. Since conventional iron circuit lenses are already used to their limits, as set by the saturation of the ferromagnetic circuit, significant improvements are to be expected only from iron-free lenses or highly saturated pole piece lenses. Their performance is restricted by the current density allowed in the windings and, further, for the iron-free lens, by the attainable mechanical tolerances, since, in the absence of iron, a lack of axial symmetry in the windings directly results in parasitic aberrations. For making small iron free lenses, high-Tc thin films are potentially interesting candidates, as they possess a high current density and can be patterned very accurately using lithographic techniques. Advantages to be expected from thin film lenses are smaller dimensions and better optical properties. An overview of fabrication techniques for high-Tc thin films is given in Section 4. The first attempt to make a coil in a superconducting thin film, using co-evaporated YBa2Cu3O7?x films, is the subject of Section 5. A thin film has to be patterned with some form of spiral in order to obtain a coil. Therefore, thin film lenses basically do not possess full axial symmetry. The relationship between the geometry of a flat coil and its optical properties is given in Section 6. The geometry of a feasible thin film lens element, along with its corresponding optical properties, is given in Section 7 while the technology used to fabricate this lens element is the subject of Section 8. Finally, based upon the work presented here, Section 9 treats the potential applicability of high-Tc superconductors in instruments that employ particle beams.
关键词： magnetic electron lenses,High-Tc superconductors,thin films,capacitive alignment,lens design,YBa2Cu3O7?x,superconductivity,electron microscopy
更新于2025-09-23 15:23:52
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Effects of receiver parameters on the optical performance of a fixed-focus Fresnel lens solar concentrator/cavity receiver system in solar cooker
摘要： To facilitate building integration with solar cooker for household, a solar cooker based on a fixed-focus Fresnel lens solar concentrator/cavity receiver system was proposed. To increase the system optical efficiency, the cavity receiver with bottom reflective cone was used as a fixed receiver. Expecting to optimize the system and receiver of better optical performance, the effects of receiver parameters on it were studied. To evaluate the effects, a significance test of key factors was conducted. Comparative analysis of fixed-focus food cooking system was undertaken. The analysis shows that average optical efficiencies using cavity receiver with bottom reflective cone of spherical, cylindrical, conical are 72.23%, 68.37% and 76.40%, respectively, while that of their corresponding conventional cavity receivers are 68.49%, 31.91% and 74.61%. The former significantly increased 3.74%, 36.46% and 1.79%, respectively. Moreover, cavity receiver with bottom reflective cone angle 90° is able to hold a higher amount of incoming energy from concentrator, compared to other three angles. Increasing the bottom reflective cone reflectivity and cavity receiver surface absorptivity can improve optical efficiency. In addition, the cavity receiver surface absorptivity and concentrated sunlight incidence angle have the most significant influence on the optical efficiency and flux uniformity, respectively. The conical cavity receiver with bottom reflective cone is the most suitable one for system. This work is expected to be useful for further optimization of solar concentrator/cavity receiver system.
关键词： Cavity receiver,Solar cooker,Fixed-focus,Fresnel lens,Optical performance
更新于2025-09-23 15:23:52
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Investigation of effect of fresnel lens on the performance of double slope single basin solar still
摘要： The shortage of drinking water has become one of the biggest problems in the world. Water pollution increases considerably because of factors such as population growth, industrialization, urbanization, etc. Several new technologies have been invented for desalination from time to time and solar distillation is considered more economical. In this work, the influence of Fresnel lens on the conversion of the polluted water that is coming out from the industries into the drinking water was investigated using double slope single basin solar still. The industrial waste water (of pH value of 14) was used in the solar still and was converted into the drinkable water. The results show that the polluted industrial waste water can effectively be converted into drinkable water with the use of Fresnel lens.
关键词： double slope,Fresnel lens,solar still,desalination,water
更新于2025-09-23 15:23:52