X射线衍射光学部件的制备及其光学性能表征

综述了国内外在纳米加工X射线衍射光学透镜方面的研究现状和最新进展。介绍了作者团队过去三年在这方面做的工作。针对衍射透镜关键技术,研发了具有大高宽比形貌的电子束光刻基础工艺;结合金电镀,提出了纳米尺度波带片的制造技术,并将该工艺成功扩展于分辨率板(Siemens star)和集成光栅型会聚透镜的研制。运用蒙特卡罗模拟和显影动力学,探索了电子束光刻技术所能够实现的最大高宽比以及造成这种限制的物理根源;成功研制了50~100nm的波带片透镜(其中,100nm波带片高宽比为16∶1)、50~300nm的分辨率测试板(其中,300nm测试板高宽比为10∶1)和200nm的会聚透镜(高宽比为10∶1)。对所研制的光学部件在同步辐射光源进行了实验表征。结果表明,100nm波带片聚焦斑尺寸为234nm,测试板和会聚透镜的光学特性与国外同样光学部件到达同等水平;会聚透镜辐照的均匀性为99%。最后,总结了近几年我国X射线衍射透镜的发展进度,指出了衍射光学部件光学性能发展的最大瓶颈是分辨率与衍射效率相互制约,提出了提高光学部件衍射效率的具体途径,给出了我国X射线衍射透镜技术的未来发展路线图。     

Spatial-energy characteristics of the focal areas of bifocal diffractive-refractive intraocular lenses

Computer simulation was performed for the measurement process of the parameters of MIOL-Akkord bifocal diffractive-refractive lenses in which the central area of the diffractive element is reduced and spherical aberrations of the eye are compensated. The spatial-energy characteristics of an ideal diffractive lens are preliminarily calculated using existing formulas. The simulation of the process of controlling the intraocular lens parameters has shown that the intensity distribution along the optical axis does not characterize the diffraction efficiency, which is the total (integrated) intensity in the beam cross section at the focus. It has been found that due to the mutual influence of diffraction orders, it is difficult to measure the absolute diffraction efficiency and it is better to evaluate only the relative efficiency.     

衍射光学透镜的设计

介绍一种衍射光学透镜的通用设计方法,它适用于大的相对孔径和任意物像共轭距离,同时考虑了透镜基板厚度的影响。设计结果,用激光写入法加工成透镜,其成像质量达到衍射极限。     

Chromatic aberrations of diffractive-refractive intraocular lenses in an eye model

Results of analyzing chromatic aberrations of an eye model with different designs of intraocular lenses (IOLs), that is, artificial crystalline lenses (refractive, diffractive-refractive, diffractive, and harmonic, i.e., multiorder lenses) are represented. Investigations were carried out sequentially for elements of the model, namely, for a cornea, refractive and diffractive components, and IOL, and as a whole, for a cornea + IOL. It is shown that diffractive-refractive IOLs in which the diffractive components produce a positive additional focal power possess the best chromatic characteristics. Chromatic aberration of the eye model with such IOLs is 2 times less than that of a model with a refractive IOL, whereas with other IOL designs it is 2 times greater and even more.     

Features of optical surfaces of multifocal diffractive-refractive eye lenses

This paper considers shape features of the surface structures of multifocal intraocular lenses (IOLs), which, unlike bifocal IOLs, generate additional foci or extends the depth of focus, which not only corrects near and far vision but also provides good vision at intermediate distances. Expansion of the field of clear vision is achieved due to the effects of diffraction, interference, and refraction (change in the radius of curvature of the lens surface). The optical characteristics of the most famous multifocal IOLs (trifocal and quadrafocal lenses and lenses with extended focal area) are given.     

Diffractive-Refractive Intraocular Lenses with Binary Structures

The paper presents a brief analytical review of papers dealing with the use of simple binaryphase diffractive structures in multifocal artificial eye lenses (intraocular lenses) to increase the focal region. The results of theoretical studies of the influence of spherical aberrations of the eye, the optical power of the diaphragm (pupil diameter), and the duty cycle of the structure on the depth of focus (limits of clear vision) are given. The intensity distribution in diffraction orders (foci) in the simplest binary diffractive-refractive intraocular lenses is analyzed.     

水下成像镜头的光学设计

水下光学成像技术,如水下摄影、水下电视、水下激光距离选通成像系统等,是海洋研究与开发的得力工具,但由于水对光的散射和吸收等特殊的光学特性,以及使用环境的特殊性,使水下光学成像系统的设计和研制较陆上光学系统有更大的难度。本文指出了主要的技术关键,及设计与使用水下光学成像系统时需注意的问题,最后给出了水下电视光学成像系统设计研制的实例。     

A new high-aperture glycerol immersion objective lens and its application to 3D-fluorescence microscopy

High‐resolution light microscopy of glycerol‐mounted biological specimens is performed almost exclusively with oil immersion lenses. The reason is that the index of refraction of the oil and the cover slip of ~1.51 is close to that of ~1.45 of the glycerol mountant, so that refractive index mismatch‐induced spherical aberrations are tolerable to some extent. Here we report the application of novel cover glass‐corrected glycerol immersion lenses of high numerical aperture (NA) and the avoidance of these aberrations. The new lenses feature a semi‐aperture angle of 68.5°, which is slightly larger than that of the diffraction‐limited 1.4 NA oil immersion lenses. The glycerol lenses are corrected for a quartz cover glass of 220 µm thickness and for a 80% glycerol‐water immersion solution. Featuring an aberration correction collar, the lens can adapt to glycerol concentrations ranging between 72% and 88%, to slight variations of the temperature, and to the cover glass thickness. As the refractive index mismatch‐induced aberrations are particularly important to quantitative confocal fluorescence microscopy, we investigated the axial sectioning ability and the axial chromatic aberrations in such a microscope as well as the image brightness as a function of the penetration depth. Whereas there is a significant decrease in image brightness associated with oil immersion, this decrease is absent with the glycerol immersion system. In addition, we show directly the compression of the optic axis in the case of oil immersion and its absence in the glycerol system. The unique advantages of these new lenses in high‐resolution microscopy with two coherently used opposing lenses, such as 4 Pi‐microscopy, are discussed.     

泡沫金属填充板式换热器的传热特性研究

以空气为介质对泡沫金属填充板式换热器的综合性能进行了试验研究,主要研究了不同孔密度的泡沫金属填充板式换热器的传热效率及压力损失。结果表明:对于以空气为介质的板式换热器,填充泡沫金属后,在较小的压力损失下传热效率得到显著提高,压力损失随孔密度的增大而增大。研究结果对设计制造轻型紧凑的高效换热器有工程实用价值。     

Effect of the eye pupil diameter and the phase shift in the diffraction structure on bifocal properties of diffractive-refractive intraocular lenses

As the eye pupil decreases, the bifocal properties of the intraocular lens (IOL), which is an artificial eye lens, can be violated. To avoid it, a phase shift is introduced into the structure of the IOL diffractive component. Results of an analytical study of the light intensity distribution on the axis of a bifocal IOL for different values of the eye pupil and phase shift in the diffractive component with a focal power of 4.2 D (diopters) are presented. Because of broadening and asymmetry of the intensity distribution function arising at small pupil diameters, the foci of orders 0 (far vision) and +1 (near vision) of the bifocal IOL are demonstrated to affect each other: they come closer or farther, become separated or overlapped. The total intensity distribution may be continuous or have a dip whose magnitude depends on the pupil diameter and phase shift. It is noted that the optimal phase shift at which separation of the foci (bifocality) begins from the pupil diameter of ∼0.9 mm and is not violated with further pupil expansion is 180° (π radian).     

红外双波段双视场共光路光学系统

考虑红外多波段双视场共光路系统多谱段色差严重且能量透过率低,本文设计了结构简单的红外中波/长波双波段双视场折射系统,实现了成像系统的功能多样性。该系统采用了320pixel×240pixel红外中波和长波双色焦平面阵列探测器,通过引入非球面元件提高了系统校正像差的能力,实现了镜片组的结构性调整。系统包括变焦和二次成像两个子系统,其中变焦系统短焦距为50mm,长焦距为200mm,满足100%冷阑匹配。像质评价结果表明:在17lp/mm处,调制传递函数(MTF)在中波处大于0.5,在长波处两个视场下都接近衍射极限;另外80%左右的能量都能被集中在一个像元上,光谱透过率均匀,且无严重的冷反射现象。优化后的光学系统具有适用范围广,结构紧凑以及成像效果好等优点,在机载光电侦察跟踪设备上有较好的应用前景。     

A Hybrid Search Algorithm for Porous Air Bearings Optimization

The study deals with the development of a hybrid search algorithm for efficient optimization of porous air bearings. Both the compressible Reynolds equation and Darcy's law are linearized and solved iteratively by a successive-over-relaxation method for modeling parallel-surface porous bearings. Three factors affecting the computational efficiency of the numerical model are highlighted and discussed. The hybrid optimization is performed by adopting genetic algorithm (GA) for initial search and accelerated by simplex method (SM) for refined solution. A simple and useful variable transformation is presented and used to convert the unconstrained SM to a constrained method. In this study, the hybrid search algorithm for a multi-variable design exhibits better efficiency compared with the search efficiency by using the SM. The proposed hybrid method also eliminates the need of several trials with random initial guesses to ensure high probability of global optimization. This study presents a new approach for optimizing the performance of porous air bearings and other tribological components.     

Improvement of form accuracy and surface integrity of Si-HDPE hybrid micro-lens arrays in press molding

Press molding of silicon (Si)/high-density polyethylene (HDPE) composite is an important technology for producing thin hybrid infrared (IR) optics with microstructures. In this research, Si-HDPE hybrid micro-lens arrays were press molded under various conditions, and the form accuracy and surface integrity of the molded lenses were evaluated. Air trapping occurs inside the micro-lens cavities during molding in a non-vacuum environment, which leads to severe surface defects. To investigate the air trapping phenomenon, a new in-situ observation system was developed which enables real-time direct observation of the molding process. From the in-situ observations, it was found that air traps were formed among the HDPE pellets during melting, and an increase in the pressing force will increase the pressure of the trapped air, forming trenches on the lens surface. The trapped air also impacts the mold coating, causing trench formation on the coating surface. To minimize air trapping, the molding temperature, and pressing force must be strictly controlled. By performing press molding in a vacuum environment, trench formation was completely eliminated. Moreover, polymer shrinkage compensation was performed to improve the lens form accuracy.     

Hybrid evolutionary algorithm with marriage of genetic algorithm and extremal optimization for production scheduling

This paper presents a hybrid evolutionary algorithm with marriage of genetic algorithm (GA) and extremal optimization (EO) for solving a class of production scheduling problems in manufacturing. The scheduling problem, which is derived from hot rolling production in steel industry, is characterized by two major requirements: (i) selecting a subset of orders from manufacturing orders to be processed; (ii) determining the optimal production sequence under multiple constraints, such as sequence-dependant transition costs, non-execution penalties, earliness/tardiness (E/T) penalties, etc. A combinatorial optimization model is proposed to formulate it mathematically. For its NP-hard complexity, an effective hybrid evolutionary algorithm is developed to solve the scheduling problem through combining the population-based search capacity of GA and the fine-grained local search efficacy of EO. The experimental results with production scale data demonstrate that the proposed hybrid evolutionary algorithm can provide superior performances in scheduling quality and computation efficiency.     

Miniature magnetic electron lenses with permanent magnets

New permanent magnet materials offer the possibility of designing lenses for applications at lower voltages. This paper briefly presents the finite-element method (FEM) program for computation of lenses based on permanent magnets. The design of a lens unit for a low-voltage TEM, realized in Brno, is described together with some design proposals of SEM and STEM lenses and computed results for a rotation-free projector proposed by Le Poole in 1972.     

Processes for manufacturing multifocal diffractive-refractive intraocular lenses

Manufacturing methods and design features of modern diffractive-refractive intraocular lenses are discussed. The implantation of multifocal intraocular lenses is the most optimal method of restoring the accommodative ability of the eye after removal of the natural lens. Diffractive-refractive intraocular lenses are the most widely used implantable multifocal lenses worldwide. Existing methods for manufacturing such lenses implement various design solutions to provide the best vision function after surgery. The wide variety of available diffractive-refractive intraocular lens designs reflects the demand for this method of vision correction in clinical practice and the importance of further applied research and development of new technologies for designing improved lens models.     

照相镜头彩色还原增透膜的作图设计法

本文分析了影响照相镜头色贡献指数的主要因素,着重地研究了增透膜在改善照相镜头彩色还原性能方面所起的重要作用。根据国际标准,指出了照相镜头色还原性的评价指标,论述了照相镜头彩色还原增透膜的设计思想,建立了一种实用的设计方法——作图设计法,并且通过实例介绍了这种方法的实际应用。     

Wave methods for modeling refractograms for diagnostics of gradients of phase inhomogeneity

A method for modeling refraction patterns of structured laser radiation propagating in optically inhomogeneous media was developed. Wave models of structured beams that simultaneously account for refraction and diffraction effects were used. Results of modeling refraction in gradient inhomogeneities using the Kirchhoff method and the spectral method are presented.     

Device for Characterization of the Diffraction Pattern of Computer-Generated Holograms in a Wide Angular Range

Results of the development and testing of a device for detecting and analyzing the diffraction pattern of computer-generated holograms are reported. It is demonstrated that this device allows characterization of the diffraction pattern of radiation reflected from the surface microrelief of the considered element or transmitted through it in the angular range of diffraction of the order of ±90° and 360° in terms of the azimuthal angle. A possibility of determining the periods, duty cycle, and angular orientation of diffraction structures and also the diffraction efficiency of all diffraction orders of the examined element is described. The device is designed for real-time monitoring of the microrelief depth and shape of computer-generated holograms in the course of their fabrication.     

The attachment of mineralised tissues to coverslips for observing dynamic events by confocal microscopy

In confocal scanning optical fluorescence microscopy, using high-aperture oil immersion lenses, the best images are obtained for focus planes immediately under the coverslip, or under a continuation of the coverslip with a medium with the same, high refractive index. Therefore placing the coverslip with a layer of oil underneath it is an advantage if the sample will allow it. If experimental manipulations that can displace the coverslip are involved, —for example, attempts to make dynamic observation of fluid flow—the coverslip is best cemented to the sample with a high-index material. This report describes the use of adhesive systems developed for restorative dentistry to achieve a durable attachment of dental tissues to microscope coverslips. The technique described in this paper has been used for monitoring real-time fluid movement in dentine. The samples were examined with a high-frame-rate confocal microscope (a tandem scanning microscope). The adhesive technology also could be utilised in the microscopic preparation of other porous translucent materials.