Methods of Checking the Optical Characteristics of Soft Contact Lenses

A new classification is proposed for contact lenses based on standard specimens (tolerance monitoring). The best wavelengths have been determined for measuring the spectral transmission coefficients of the standard specimens, and realistic bounds have been defined for the tolerance fields for the most common colors of these lenses.     

FEM/BEM for simulation of LSAW devices

This paper presents a modeling of the propagation of surface acoustic, leaky acoustic, and surface skimming bulk waves in piezoelectrics with a finite array of metallic electrodes over their surface. A combined method of matrix Green's function and the finite element method for computation of all acoustic wave fields is an effective tool for simulation of the propagation of acoustic waves in such structures. The proposed method is optimized in the speed of computation of all matrix Green's function components originally obtained. The Fourier transformations of Green's function from kappa-space domain to real space domain are performed by combined trapezoidal and Filon's integration methods for rapidly oscillating functions. The trapezoidal integration method is used on a distance from a point source from zero to a few wavelengths long, but the other has the advantage for a distance from some wavelength to infinity. That allows one, by selectively condensing computation grids around branch and singular points of the sharp behavior of Green's function, to maximize speed and accuracy of computation of integrals. FEM is used, modified originally to achieve acceleration without loss accuracy. Because of the simple geometry of the electrodes, unknown elastic fields are presented as a series of known eigenfunctions with unknown coefficients over the whole region of electrodes. All unknown coefficients are determined by applying the Galerkin method. There is good agreement between numerical and experimental conductances of acoustic wave transducers on materials such as lithium niobate and lithium tantalate.     

Modification of the formulas for third-order aberration coefficients

New parameters for calculation of third-order aberration coefficients (Seidel aberration coefficients) are introduced. The formulas for Seidel aberration coefficients are linear in these new variables. With these new variables it is possible to calculate the shape and the refractive index of the glass of the individual lenses of the optical system, which was not possible before.     

基于微扰理论的静电电子透镜的缺陷电场计算

研究了用于计算电子光学系统的缺陷电场和容差的微扰理论。基于微抗原理，推导了计算静电电子透镜由于电极偏心、倾斜和加工不圆造成的电场变化及其旁轴多极场展开函数的九点有限差分公式，编制了计算软件。建立了两个电场解析模型，通过该模型的解析解与数值计算结果的对比，证实了算法及软件的正确性，并据此讨论了微扰理论用于容差计算的适用范围。计算了几个静电电子透镜的例子，给出了不同电极缺陷的电位分布和微扰多极场分布。     

Modelling the primary chromatic aberrations and secondary spectrum of conceptual thick-lens modules

A virtual thick-lens module comprising three air-spaced thin lenses is proposed, which is able to have the identical primary chromatic aberrations and secondary spectrum for just real thick lenses, or groups or components within any thick lens, hence it is capable of studying the chromatic aberration behaviours of conceptual lenses without their detailed structures. The three thin-lens powers are first evaluated to match the required first-order quantities. Then the chromatic aberration coefficients of each thin lens are solved to satisfy the given system aberrations associated with the reference optical configuration. When the incident rays are changed, each thin lens will induce new chromatic aberrations according to the thin-lens formulae. The new system aberrations are obtained by adding those individual thin-lens aberrations together. The module can be directly applied to finite and infinite conjugates, focal and afocal lenses, as well as telecentric and non-telecentric lenses. Evaluations of the chromatic aberration variations of three different types of lenses are demonstrated.     

Low-order aberration corrections of multilayer flat lenses using negative-index materials

A study of the corrections for some low-order aberrations of multilayer flat lenses based on the introduction of negative-index materials is presented. With the aberration coefficients of a multilayer flat lens that we provided, numerical solutions for the parameters of the double-layer three-layer, and four-layer flat lenses are investigated, respectively, to correct the aberrations, under some conditions, up to orders as high as possible. We find that with the increment of the layer number, the spherical and oblique aberrations can be corrected up to higher orders though the corresponding ranges of the refractive indices and working distances become narrower.     

两探测面结构激光粒度仪的接收光路设计

为了扩大激光粒度仪测量的动态范围,采用同轴的两组接收透镜,将两个硅光电探测器阵列分别置于前组透镜的后焦面和两组透镜的组合后焦面上,对测量信号进行组合后用改进共轭梯度法处理数据。通过优化光路结构,采用两组双胶合透镜和探测环半径均不大于45mm的探测器可满足同时测量5～3500μm粒径的要求。     

Recent Advances in Transparent Electronics with Stretchable Forms

Advances in materials science and the desire for next‐generation electronics have driven the development of stretchable and transparent electronics in the past decade. Novel applications, such as smart contact lenses and wearable sensors, have been introduced with stretchable and transparent form factors, requiring a deeper and wider exploration of materials and fabrication processes. In this regard, many research efforts have been dedicated to the development of mechanically stretchable, optically transparent materials and devices. Recent advances in stretchable and transparent electronics are discussed herein, with special emphasis on the development of stretchable and transparent materials, including substrates and electrodes. Several representative examples of applications enabled by stretchable and transparent electronics are presented, including sensors, smart contact lenses, heaters, and neural interfaces. The current challenges and opportunities for each type of stretchable and transparent electronics are also discussed.     

Rayleigh wave reflection and scattering calculation by source regeneration method

The analysis and precise calculation of reflection and scattering of Rayleigh wave by electrodes is important for surface acoustic wave (SAW) device models, especially for SAW identification (ID) tag design. We present a source regeneration method, which utilizes Green's function combined with finite-element method (FEM)/boundary-element method (BEM) to obtain accurate values of reflection, transmission, and scattering coefficients in a direct way. We take one electrode as the reflector on 128 degrees YX-LiNbO3 substrate to show the result as an example. The results are very accurate and are obtained with short computing time. The new analysis way shows its powerful ability for other advanced discussion of SAW devices.     

Image fidelity for single-layer and multi-layer silver superlenses

In response to increasing interest in the area of subdiffraction-limited near-field imaging, the performance of several different realizable and theoretical superresolving silver-based lenses is simulated for a variety of different input object profiles. A computationally-efficient T-matrix technique is used to model the lenses, which consist of layers of silver with total width of 40 nm sandwiched between layers of polymethyl methacrylate and silicon dioxide. The lenses are exposed to nonperiodic bright- and dark-slit input patterns, with feature size varied between 1 nm and 2.5 microm. The performance of the lenses is characterized in terms of transfer function, contrast profile, error profile, and input-to-output correlation. It is shown that increasing the number of layers in a lens increases the lens' transmission coefficients at high spatial frequencies; however, this does not always lead to better imaging performance. The main reasons for this are lens-specific resonances that distort features at certain spatial frequencies, and the increased attenuation of the DC component of transmitted images, which reduces image fidelity, particularly for dark-line features. This suggests that, to achieve optimum results, the design of the superresolving lens system should take into account the characteristics of the images that it is expected to transmit.     

Design and evaluation of a THz time domain imaging system using standard optical design software

A terahertz (THz) time domain imaging system is analyzed and optimized with standard optical design software (ZEMAX). Special requirements to the illumination optics and imaging optics are presented. In the optimized system, off-axis parabolic mirrors and lenses are combined. The system has a numerical aperture of 0.4 and is diffraction limited for field points up to 4 mm and wavelengths down to 750 microm. ZEONEX is used as the lens material. Higher aspherical coefficients are used for correction of spherical aberration and reduction of lens thickness. The lenses were manufactured by ultraprecision machining. For optimization of the system, ray tracing and wave-optical methods were combined. We show how the ZEMAX Gaussian beam analysis tool can be used to evaluate illumination optics. The resolution of the THz system was tested with a wire and a slit target, line gratings of different period, and a Siemens star. The behavior of the temporal line spread function can be modeled with the polychromatic coherent line spread function feature in ZEMAX. The spectral and temporal resolutions of the line gratings are compared with the respective modulation transfer function of ZEMAX. For maximum resolution, the system has to be diffraction limited down to the smallest wavelength of the spectrum of the THz pulse. Then, the resolution on time domain analysis of the pulse maximum can be estimated with the spectral resolution of the center of gravity wavelength. The system resolution near the optical axis on time domain analysis of the pulse maximum is 1 line pair/mm with an intensity contrast of 0.22. The Siemens star is used for estimation of the resolution of the whole system. An eight channel electro-optic sampling system was used for detection. The resolution on time domain analysis of the pulse maximum of all eight channels could be determined with the Siemens star to be 0.7 line pairs/mm.     

Three-shell-based lens barrel for the effective athermalization of an IR optical system

We have developed a new IR optical system that consists of three mirrors and four lenses, and that operates in the temperature range 8°C-32°C. This temperature range can induce thermoelastic deformation in the lenses and their mounting subassembly, leading to a large defocus error associated with the displacement of the lenses inside the barrel. We suggest using a new three-shell-based athermalization structure composed of two materials with different coefficients of thermal expansion (Invar and aluminum). A finite element analysis and the experiment data were used to confirm that this new athermalization barrel had a defocus error sensitivity of 11.6?nm/°C; this is an improvement on the widely used conventional single-shell titanium barrel model, which has a defocus error sensitivity of 29.8?nm/°C. This paper provides the technical details of the new athermalization design, and its computational and experimental performance results.     

The electrostatic problem for the SAW interdigital transducers inan external electric field. I. A general solution for a limited numberof electrodes

An exact solution for finding the surface charge and electric field distributions in interdigital transducers (IDTs) with a limited number N of electrodes is given. It is based on the Keldysh-Sedov solution to the mixed boundary problem of the analytic function theory. The IDT electrodes are placed on the plane boundary between two anisotropic dielectric media. The external electric field may arbitrarily vary along the structure. The solution contains N constants which may be found from the electrodes' connection conditions. For determining these constants a linear set of algebraic equations is obtained. The coefficients of this system are written in explicit form. The capacitance coefficients for a system of electrodes of different widths are obtained. For illustration purposes systems with one and two electrodes are considered in greater detail. In these cases the external electric field is assumed to vary harmonically along the structure with an arbitrary wavenumber. For one electrode the Fourier transform of the charge distribution is obtained in terms of the Bessel functions. For two electrodes of different widths a simple expression for the capacitance is found. The charge and electric field distributions are represented graphically for several wavenumbers and geometrical sizes of the electrode system. Section I contains a survey, including Russian literature, which is not well known in the west     

球差对电子束轰击炉电子光学系统磁聚焦的影响研究

对电子束轰击炉电子光学系统磁聚焦过程中产生的球差进行了研究。分析了有限放大倍数下磁透镜产生的球差系数。根据两个磁透镜各自的球差系数建立了双聚焦系统球差系数的数学模型。为减小球差对双聚焦系统聚焦效果的影响提供理论依据。     

The Influence of Inaccuracy of Construction Parameters on the Calculated Optical Transfer Function

The influence of the construction parameters of an optical system such as radii of curvature, refractive indices, thicknesses, and distances of lenses on the optical transfer function (O.T.F.) is discussed with the example of variation of radii. To find out the critical or uncritical parameters of a compound system, the Seidel coefficients (first aberration) are generally sufficient. Then the exact coefficients of wave aberrations are varied by given amounts and the corresponding O.T.F. is calculated and tabulated. The permissible variation of the coefficients for a given tolerance of O.T.F. in a limited spatial frequency range can be seen from the table. The presented technique is demonstrated for a lens of nine surfaces.     

提高镭射光柱卡纸色标光检测信号识别精度研究

目的 针对凹版印刷以镭射光柱纸作为承印物,镭射光柱对色标检测传感器产生干扰,致使镭射光柱纸不能使用传统套印工艺进行印刷,提出一种可直接在镭射光柱区域直接印刷套准色标的新工艺与技术方案。方法 对色标传检测感器检测原理进行分析,分析镭射光柱纸的特点以及对色标传感器造成的干扰。根据镭射光柱光谱反射率曲线来进行滤光镜片的选取,同时也加入衰减镜片以及消光膜进行组合实验测量电压,实验使用松德凹印机组进行。以白卡纸套印电压作为参考,选取不同镜片组合进行生产打样。结果 镜片组合可以滤除镭射光柱,色标传感器能准确检测色标光信号,上机打样满足高精度多色套印,且不需要复杂的镂空、遮盖工艺,节省了一组色序,并节省了2%的承印物原材料。结论 对色标检测传感器检测原理的分析以及对镭射光柱纸的光谱反射率曲线的测量,实现了使用滤光镜片组合对镭射光柱的滤除,证明了套准标记可直接印刷在镭射光柱区域的可行性。同时,提高了承印物的利用率,减低了油墨使用量。     

Overoxidized polypyrrole films: a model for the design of permselective electrodes.

Studies have been conducted to further characterize overoxidized polypyrrole films grown on carbon electrodes. Differences in apparent diffusion coefficients for various probes are interpreted via a model based on both hydrophobic and electrostatic interactions between the probe and polymer film. These electrode coatings are also compared to Naflon films, and the results of this study are discussed in terms of important considerations for the design of permselective electrodes.     

High accuracy dual lens transmittance measurements

We show how to determine the transmittance of short focal length lenses (f approximately 19 mm and f approximately 2 5 mm, in this case) with a combined uncertainty of 3 parts in 10(4) or better by measuring transmittances of lens pairs of a set of three or more lenses with the same nominal focal length. Uncertainties are minimized by optimizing the radiometric design of the setup and the measurement procedure. The technique is particularly useful in systems where the detector acceptance angle limits the beam geometry to relatively collimated beams.     

Numerical parametric lens for shifting, magnification, and complete aberration compensation in digital holographic microscopy

The concept of numerical parametric lenses (NPL) is introduced to achieve wavefront reconstruction in digital holography. It is shown that operations usually performed by optical components and described in ray geometrical optics, such as image shifting, magnification, and especially complete aberration compensation (phase aberrations and image distortion), can be mimicked by numerical computation of a NPL. Furthermore, we demonstrate that automatic one-dimensional or two-dimensional fitting procedures allow adjustment of the NPL parameters as expressed in terms of standard or Zernike polynomial coefficients. These coefficients can provide a quantitative evaluation of the aberrations generated by the specimen. Demonstration is given of the reconstruction of the topology of a microlens.