基于液体透镜的自动变焦扫描镜头的设计与验证

由于定焦镜头自身的景深问题使传统的扫码器不具备大的工作距离。为了满足工作人员在不更换扫描器的情况下既能实现近距离的信息读取又能实现十几米外的信息读取,研发了一款基于电润湿（electrowetting on dielectric,EWOD）液体透镜的自动变焦扫描镜头。通过调整液体镜片形状来实现镜头参数特别是焦距的变化,使得从近到远的所有对象都能成像在焦面上,从而达到自动变焦的效果。通过Zemax软件设计出一款成像范围为80 mm至无穷远的自动变焦扫描镜头,并完成了成像质量的验证。     

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.     

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.     

液体透镜的发展趋势

由于光电仪器日益小型化和轻量化,从而在系统中越来越多地采用了一些像非球面和自由曲面光学零件、折射—衍射混合光学零件等新型的光学零件。但是,随着镜头的变小,在很小的空间内已无法使用原有的机械方法实现对焦和变焦的功能。这就是研发小尺寸、可变焦距的液体透镜的目的。文中系统地介绍了通过调整电压或其他物理量的方法,改变介质的折射率(液晶透镜)或面型(液体透镜),从而可以改变其焦距的透镜。目前基于电湿润法原理的液体透镜已经商品化,并已经开始大量的用于手机的照相光学模组中,实现了对不同距离的物体进行对焦。但由于液体透镜的研发仅仅是开始,还有很多的性能要改善、还有很多的关键课题等待去解决。     

Remote focusing in confocal microscopy by means of a modified Alvarez lens

Alvarez lenses are actuated lens‐pairs which allow one to tune the optical power by mechanical displacement of subelements. Here, we show that a recently realized modified Alvarez lens design which does not require mechanical actuation can be integrated into a confocal microscope. Instead of mechanically moving them, the sublenses are imaged onto each other in a 4f‐configuration, where the lateral image shift leading to a change in optical power is created by a galvo‐mirror. The avoidance of mechanical lens shifts leads to a large speed gain for axial (and hence also 3D) image scans compared to classical Alvarez lenses. We demonstrate that the suggested operation principle is compatible with confocal microscopy. In order to optimize the system, we have drawn advantage of the flexibility a liquid‐crystal spatial light modulator offers for the implementation. For given specifications, dedicated diffractive optical elements or freeform elements can be used in combination with resonant galvo‐scanners or acousto‐optic beam deflectors, to achieve even faster z‐scans than reported here, reaching video rate.     

Mirror lenses in light microscopy—Theoretical considerations and practical implications

Various types of mirror lenses were developed some decades ago designed for several special tasks in microscopy. When compared with high‐end glass lenses, mirror lenses lead to an extraordinary image quality because of their supraapochromatic color fidelity and their high planarity; the working distances are significantly longer, and in most cases, the depth of field and resolution are higher than in concurrent glass lenses. In this respect, the microscopic advantages of mirror lenses seem to be comparable with the advantages of mirror telescopes in astronomy; for in observations of celestial bodies, mirror telescopes lead to better results than refractors based on glass lenses. When mirror lenses are available in light microscopy, not only common illumination modes can be carried out in transmitted or incident light, but also new and specific axial illumination techniques can be utilized, which cannot be achieved with normal glass lenses. This axial illumination, called “luminance contrast,” can be carried out in various modes, so that the resulting images can be compared with dark‐field, phase or interference‐contrast images. In all variants, especially, fine details within transparent specimens can be visible in maximized contrast and resolution, and blooming or haloing artifacts are significantly reduced or absent. These findings are based on theoretical consideration, and intensive practical tests carried out with several mirror lenses constructed in various optical designs. All in all, supramicroscopic image qualities could be expected if mirror lenses were produced based on the optimized manufacturing techniques available nowadays. Microsc. Res. Tech. 2010. © 2009 Wiley‐Liss, Inc.     

Studies on condenser-objective lenses

Scaling down the dimensions of a conventional magnetic objective lens to reduce aberrations is studied in detail. The values of other aberration coefficients for optimum lens size corresponding to desired minimum aberration are estimated. The possibility of using iron-free condenser–objective lenses at high voltage is examined.     

渐变焦眼镜片的设计方法研究

介绍了渐变焦眼镜的基本结构,阐述了镜片的设计思想,论述了其由上而下光焦度分布与整体面型设计的基本原理。构建了子午线上光焦度分布的多项表达式,运用欧拉公式和拉普拉斯方程的变分法知识给出渐变焦眼镜屈光度等高线为圆形的面型设计,并给出了这种渐变焦镜片表面矢高的表达式。比较了选取不同参数的3种子午线设计的渐变焦镜片的各自特点,分析了适合不同个性化需求的渐变焦镜片子午线屈光度分布。并在最后给出了其中一种方法的设计实例。     

塑料光学透镜的磁悬浮检测

考虑传统的塑料透镜检测方法操作繁琐、耗时长,本文提出了一种针对小型塑料光学透镜的磁悬浮检测理论与方法,并设计制造出了相关检测装置。该方法利用磁场对顺磁溶液的磁化作用,将逆磁性被测样品(塑料透镜)在溶液中悬浮起来,通过观察透镜在装置中的高度、中心位置和平衡状态下与水平面的偏斜程度,检测透镜是否存在外观不完整和内部存在气泡等不均匀性的缺陷,并确定出透镜缺陷存在的位置。通过合格透镜、外形不完整透镜、内部存在气泡透镜和功能不合格透镜开展了多项实验研究来验证该方法的可行性与有效性。结果显示,该方法的检测精度高、灵敏度高、操作简便且适应性广,在0.5mm的测量误差下,密度的测量精度高达0.003g/cm3;对直径小于10mm的透镜,可检测出总体积在0.017mm3的内部气泡缺陷。提出的方法在塑料光学透镜的检测方面很有应用潜力。     

一款条码扫描成像镜头的多方案设计和选择

设计了一种扫描成像镜头,镜头焦距为7.9mm,视场角为52°,采用CMOS线性传感器接收。为了使镜头成本更低,同时保证好的成像性能,引入了塑料非球面,设计了一个含有高次塑料非球面镜片和一个玻璃球面镜片(1G1P)的结构。相对传统三片式玻璃球面镜片(3P)的结构来讲,1G1P结构的光学性能更好地满足了技术指标要求,成本为3G结构的50%,推广应用前景好。     

塑料眼镜内外缺陷检测的全内反射照明技术

考虑目前大多数塑料眼镜镜片和光学表面的缺陷检测仍由人工完成,研究了基于全内反射照明的暗场检测技术,以提高用机器视觉进行自动缺陷检测的可见度及对比度,设计了镜头检测原型系统用于增强缺陷信号的强度并降低表面浮尘的干扰.利用设计的原型系统进行了试验测试并对自动缺陷检测结果与人工检测结果进行比较,结果验证了这种暗场全内反射检测...     

Aspherical Lens Design Using Computational Lithography

Optical lithography is often applied to fabricate three-dimensional (3D) patterns because of its capability on the scale of optical wavelengths. An aligner, a laser writer, and a stepper with an optical projection system are used as the exposure tool. The focusing capability must enable exposure of step heights of ≥50 μm, which is normally achieved using an optical projection system with a large focal depth. Recently, a projection lens was developed that can produce a variable step height using an adjustable numerical aperture, which has led to the fabrication of micro-lens arrays (MLAs) with step heights as high as 100 μm. These MLAs are used in various fields but mostly only as condensing lenses. However, wider applications await the realization of optical aberration reduction. The introduction of aspherical lenses would be a major step in this direction; however, aspherical lenses are difficult to produce because of the limitations in processing and polishing the aspherical surfaces of optical elements made of glass. Alternatively, the fabrication of 3D patterns using optical lithography involves a photomask whose optical density distribution corresponds to the 3D profile after exposure and development. A density distribution corresponding to the desired 3D shape can be achieved using a computer to control the dot density of a microdot mask pattern. In this study, we present a design method for low-aberration aspherical MLAs that satisfies the Rayleigh standard using computational lithography.     

Friction coefficient of soft contact lenses: measurements and modeling

Tribological conditions for contact lenses have very low contact pressures in the range 3–5 kPa and sliding speeds around 12 cm/s. Using a microtribometer a series of experiments was run on commercially available contact lenses made from Etafilcon-A. These tests were run using 10–50 mN of normal load at speeds from 63 to 6280 m/s using a 1-mm radius glass sphere as a pin. The resulting contact pressures are believed to be nearly an order of magnitude larger than the targeted 3–5 kPa. It is hypothesized that the viscoelastic nature of the hydrogel, viscous shearing of the packaging solution, and interfacial shear between the glass sphere and the contact lens all contribute to the friction forces. A model that includes all three of these contributors is developed and compared to the experimental data. The experimental friction coefficients vary from = 0.025 to 0.075. The calculated fluid filmthicknesses were between 1 and 30 nm. The average surface roughness of the lens and the glass sphere are R_a=15 nm and R_a=8 nm, respectively, suggesting that the contact is not in full elastohydrodynamic lubrication. Finally, the largest contributors to the friction force in these experiments were found to be viscous dissipation within the hydrogel and interfacial shear within the contact zone.     

口径自适应光学透镜中心厚度测量方法及装置

透镜作为光学系统中的核心部件之一,其加工质量极大影响着光学系统的使用性能。其中,透镜中心厚度的偏差对整个光学系统成像质量的影响最大。现有的非接触式和接触式测量设备都存在着一些缺点,因此本文提出了一种口径自适应光学透镜中心厚度测量方法,并基于此方法设计和搭建了一套透镜中心厚度测量装置,进行了测量精度对比和重复性测量实验。结果表明,本文所研究的测量装置误差与产线上所使用的测量装置误差相当,满足对光学透镜的检测要求。本装置具有结构简单可靠、操作方便、测量精度高且可以节省光学透镜生产成本等优点,已在生产线得到应用。     

综合验光仪光学系统研究

电脑控制式综合验光仪是目前国际上公认的主要验光设备。文中介绍了综合验光仪的光学原理,采用镜片组合屈光度的最佳方法,从技术指标和成本的角度出发分析了几种镜片分布方案,并找到最佳设计方案,通过数据分析和计算,确定了镜片的组合方式,优化镜片组合设计出整个光学系统结构。实际测量结果证明了研制的全自动综合验光仪符合国家计量校准规范要求。使用综合验光仪能够进行完整的视觉功能测试和定量分析,验光方便、快速、准确。     

An automated Guilloche machining technique for the fabrication of polygonal Fresnel lens array

Fresnel lenses are gaining wider applications in optoelectronics and photonic devices. They have been evolved into arrays of individual elements with better performance and better capabilities. These arrays may also be realized with individual elements having polygonal shapes such as rectangular, hexagonal, etc to achieve a high fill factor. Due to the fact that the polygonal Fresnel lens arrays are not rotationally symmetrical, they are manufactured by using expensive lithography techniques or time consuming method of having multiple molds assembled together. This paper presents an automated 4-axis ultraprecision machining technique for manufacturing an array of hexagonal Fresnel lenses. In the proposed method, a diamond tool moves as a fixed point on a circle rolling inside a fixed circle which is analogous to a Guilloche machine. The proposed automated machining technique has been experimentally verified through successful manufacturing hexagonal Fresnel lens array in a single process, without having separated sections assembled as a single master mold. From the results, an excellent surface finish and good profile accuracy are also achieved. The developed automated Guilloche machining technique also paves the way for the promising challenges to remove manufacturing barriers of machining freeform surfaces with complex curvatures.     

Press molding of a Si–HDPE hybrid lens substrate and evaluation of its infrared optical properties

A hybrid structure of single-crystal silicon (Si) and high-density polyethylene (HDPE) was developed as a new substrate for infrared lenses by using precision press molding. A thin HDPE film was used to laminate a silicon wafer and their interface was directly bonded by the silane cross-link. The HDPE film is easy to be hot-embossed to form three-dimensional surface microstructures and the silicon wafer provides a high stiffness for the hybrid substrate. The infrared (IR) optical properties of the hybrid substrate were examined by two kinds of measurements, transmittance and image sharpness. Interestingly, the transmittance measurement result shows that the IR transmittance of the hybrid substrate is higher than that of Si itself in some region of wavelength. The imaging test result shows that the hybrid substrate is capable to produce similar image quality as Si itself. These results strongly demonstrate that the developed Si–HDPE hybrid substrate is a promising alternative substrate material for IR lens.     

广角微型投影镜头设计

投影机更新速度快,高分辨率、轻便微小的投影机已是时代的需求。通过分析微型投影成像系统的特点,根据几何光学理论,用Zemax软件设计了一款投影显示芯片为0.61inch(1inch=2.54cm)、投射比为0.68∶1的微型投影镜头。镜头由2片非球面透镜和6片常用玻璃材料透镜组成,结构简单,系统光学总长为60mm,有效焦距为9.26mm,后工作距离大于20mm,最大口径小于23mm,全视场(FOV)为80°,相对孔径为1∶2.2。在71lp/mm特征频率处,全视场的调制传递函数均大于0.5,全视场相对畸变小于2.0%,镜头成像质量好。对微型投影系统进行容差分析,得出一套较为宽松的公差,适合生产加工。     

小型数字投影结构光三维测量仪镜头设计

为了解决三维测量仪器的小型化问题,设计了一种数字投影结构光三维测量仪光路结构,并用Zemax软件进行了性能优化。该结构分为投影光路和照相光路,投影镜头采用反远距结构,由5片透镜组成,全视场调制传递函数大于0.35。照相镜头采用双高斯结构,由6片透镜组成,全视场调制传递函数大于0.12。两镜头口径均小于14mm,长度小于40mm,像面照度均大于90%,可以对80~120mm远的物体进行测量。投影图像像素密度为1 028×768,相机拍摄图像像素密度为1 280×960,在工作距离100mm处可以测量28mm×21mm的表面。镜头全部采用球面透镜。该结构具有测量精度高、成本低、加工容易、体积小等优点。