梯度折射率球透镜的制备及其光线轨迹测试

自麦克斯韦鱼眼透镜理论模型提出后,长期以来学术界一直以为它只是一种绝对光学仪器,在实践中并没有应用的可能。但通过对麦克斯韦鱼眼微球透镜的理论研究表明,在一定条件下,它具有良好的成像性能和耦合效率。根据菲克定律推导出梯度折射率球透镜的折射率分布函数。并且熔制了含Li+硅酸盐玻璃和采用槽沉法以及Na+/Li+离子交换法制备直径为0.3—3.0mm的梯度折射率球透镜。通过干涉法测得了梯度折射率球透镜的折射率分布曲线,并研究了光线通过梯度折射率球透镜的轨迹。研究结果表明:在590℃,离子扩散系数为3.07×10-6mm2/s;所制备的梯度折射率球透镜的折射率分布是抛物线分布,并且和理论分析相吻合;梯度折射率球透镜的光线轨迹满足椭圆方程。     

Fabrication of gradient refractive index ball lenses using the method of combination of ion exchanging and sagging

Based on the Fick’s diffusion equations, the distribution function of refractive index of a gradient refractive index ball lens (GRIN ball lens/GBL) is derived. Lithium containing silicate glass is fabricated and GRIN ball lenses (GBLs) which diameters are from 0.3 mm to 3.0 mm are made by the method of combination of Ion exchanging and sagging in sodium nitrate. Refractive index profiles of these GBLs are measured by interferometer, and the performances such as effective focal length (EFL), back focal length (BFL) and numerical aperture (NA) between GBLs and homogeneous ball lenses (HBLs) are compared. Results show that the distribution of the index of refraction is parabolic curve and its Δn is about 0.0002, the performances of the former are super to the latter.     

Full-field measurement of surface reflectivity using a microscopy for refractive index profiling of GRIN lenses

This paper outlines an improved technique for profiling the refractive index of Graded-index (GRIN) lenses based on the measurements obtained from a reflectivity image. Reflective cross-sectional image of the GRIN lens were compared with a reflectance reference target under illumination at small incidence angles to obtain the full-field refractive index distribution of the GRIN lens quickly and easily.     

Performance evaluation of GRIN lenses by ray tracing method

Plastic gradient-index lenses produce clear images with negligible aberration and distortion. One of the methods for fabricating these lenses involves pulling up the core fiber vertically from a polymer solution whose refractive index has been adjusted to the desired value. Since the molecules from the solution diffuse into the inner layer, the monomer components are distributed in the radial direction. The monomer distribution is fixed in the photopolymerization process, and this forming process is repeated several times with adjusting the composition of the solution; hence, a specific refractive index distribution is obtained. We considered a numerical model of the interdiffusion process and analyzed refractive index distribution that could well reproduce the experimental results. Moreover, we employed the ray tracing method to calculate the modulation transfer function and used the transfer function to evaluate the GRIN lens performance. Simulation results showed that our evaluation method well duplicates the experimental results. We thus developed an integrated simulation method for the fabrication and performance evaluation of GRIN lenses.     

Effect of crystalline lens surfaces and refractive index on image quality by model simulation analysis

The surfaces and refractive index of crystalline lens play an important role in the optical performance of human eye.On the basis of two eye models,which are widely applied at present,the effect of lens surfaces and its refractive index distribution on optical imaging is analyzed with the optical design software ZEMAX (Zemax Development Co.,San Diego,USA).The result shows that good image quality can be provided by the aspheric lens surfaces or (and) the gradient-index (GRIN) distribution.It has great potential in the design of intraocular lens (IOL).The eye models with an intraocular implantation are presented.     

The measurement of refractive index profile and aberration of radial gradient index lens by using imaging method

In this article, through the linear fit of objective distance and reciprocal of magnification in different imaging locations, we use imaging method to measure the central refractive index n(0) and focusing constant α of radial gradient index (GRIN) lens and obtain 10⁻³ measurement accuracy of n(0). At the same time, under distortion, the fourth-order refractive index coefficient and aberration of GRIN lens are derived.     

Efficient coupling and relaxed alignment tolerances in pigtailing of a laser diode using dual ball lenses

In this paper, we report an efficient coupling scheme with relaxed misalignment tolerances. The proposed coupling scheme consists of two ball lenses of same diameter (1 mm) and different refractive indices. The second ball lens which is facing the fiber tip has a higher refractive index (1.833), whereas the first one which faces the laser diode has a refractive index of 1.5. Employing Gaussian and ABCD ray tracing optics, the theoretically obtained coupling efficiency can reach a unity with relaxed working distance (separation of the coupling system from the fiber tip) in the range between 1 and 4 mm at some optimum positions of the coupling lenses with regard to each other and to the facet of the laser diode. It has been found that if the distance between the first ball lens and the laser diode (d₁) is fixed at 1.1 mm, which is twice its focal length, the coupling efficiency and the working distance as well as the misalignment tolerances are greatly affected by variation of the separation between the two ball lenses (s), and for this proposed coupling scheme the highest coupling efficiency and largest working distance are obtained when s is in the range of 0.3-0.35 mm. Above and below this range there is a significant reduction in the values of the above-mentioned parameters. Experimentally, the Nd:YAG laser welding system has been used for the alignment and welding of the coupling components in a butterfly configuration; the experimentally obtained coupling efficiency of the proposed coupling system was around 75% with relaxed working distance. From the effect of lateral and angular offsets on coupling efficiency, it is clearly noticed that the mode field of laser diode is transformed from elliptical into circular and hence effectively matched with that of the single-mode fiber.     

梯度折射率透镜在口腔内窥镜中的设计与应用

作为口腔内窥镜的摄像镜头，利用梯度折射率透镜质量轻、体积小、结构简单、分辨率高、成像景深大的优点，研制出一套适合医患交流及进行口腔检查与治疗的医疗装置。采用修正折射率剖面的梯度折射率透镜, 降低系统渐晕，减小畸变,获取口腔内部图像，经CCD光电转换装置转换成电信号，再将电信号经过数字信号处理以后，将该数字信息存储于计算机内部或在显示器上显示出来。口腔内窥镜是集梯度折射率透镜、光学原理、光学材料与加工、微电子、数字成像技术等为一体的新型医疗设备。特别是采用经修正的梯度折射率透镜制造的口腔内窥镜成像清晰, 在图像畸变、景深等方面优于现有产品，而且便于对患者的各种信息进行管理、查询、输出等。     

梯度透镜折射率分布高次项系数的数值计算

本文从光线方程出发,给出了一系列利用径向梯度透镜球象差进行数值计算求解折射率分布高次项系数的公式及测量计算结果。     

离子交换引起的GRIN棒透镜大折射率差值分析

利用两次离子交换法制作了GRIN棒透镜样品，并采用雅明干涉法对样品的折射率分布进行了测试.结果表明，样品获得了较大的折射率差值.讨论了两次离子交换增大折射率差的原因.研究结果在制作生产梯度折射率材料方面有一定的参考价值和指导意义.     

Design,fabrication and evaluation of a photographic objective that uses a radial GRIN lens

Some technical issues in the design, fabrication and evaluation process of the photographic objective lens are treated. In the design process, a unique design technique called the quasi-equivalent glass method is applied. Also, a convenient method is described for the determination of tolerances of the refractive index profile. Performance evaluation showed that the GRIN material made by sol-gel method is usable for photographic lenses.     

Aberration improvement of gradient index rod lens

The aberration of gradient index (GRIN) rod lenses induced by deviation from the ideal refractive index distribution is decreased by optimized thermal diffusion. The index distribution coefficients are estimated by a novel method. The lenses' heat treatment process and aberration testing system are described.     

半导体激光器光束远场特性研究

精确测量了半导体激光器远场分布并与新的远场理论模型作了细致的比较，结果表明新模型在很大的角度范围内与测量数据准确地符合。     

麦克斯韦鱼眼微球透镜的研究

自麦克斯韦鱼眼透镜理论模型提出后，长期以来学术界一定以为它只是一种色对光学仪器，在实践中并没有应用的可能。但通过对麦克斯韦鱼眼微球透镜的理论研究表明，在一定条件下，它具有良好的成像性能和耦合效率。采用复合结构及多阶段离子交换工艺可制备出优质的麦克斯韦鱼眼球透镜，在微小光学和集成光学具有诱人的应用前景。     

一种具有Luneburg透镜特性的轴向GRIN介质透镜

本文给出一种轴向GRIN(梯度折射率)介质透镜。这种透镜具有 Luneburg(卢内堡)透镜的特性。它可以使无限远光线锐成象;亦可用于点—点锐成象系统,光准直或光准直—聚焦系统;在微波频谱区域及有声成象、天线设计方面有一定应用价值。     

Pupil-segmentation-based adaptive optical correction of a high-numerical-aperture gradient refractive index lens for two-photon fluorescence endoscopy

The intrinsic aberrations of high-NA gradient refractive index (GRIN) lenses limit their image quality as well as field of view. Here we used a pupil-segmentation-based adaptive optical approach to correct the inherent aberrations in a two-photon fluorescence endoscope utilizing a 0.8 NA GRIN lens. By correcting the field-dependent aberrations, we recovered diffraction-limited performance across a large imaging field. The consequent improvements in imaging signal and resolution allowed us to detect fine structures that were otherwise invisible inside mouse brain slices.     

Multistep ion exchange processes of gradient refractive index rod lens

A mathematical model for research on the refractive index profile (RIP) of multistep ion exchange processes (IEPs) of gradient refractive index rod lenses (GRINs) is established by the different initial condition and boundary condition, based on the Fickian diffusion equation. GRIN rod lenses have been fabricated using the three-step IEPs. Research results indicate that the experimental deviations of refractive index (DRI) are in good agreement with the theoretical data. The DRI of three-step IEPs is superior to the one- and two-step IEPs and smaller than 10(-5).     

微球透镜亚波长显微成像远场特性实验研究

利用低折射率的二氧化硅和高折射率的钛酸钡微球透镜对蓝光刻录光碟的亚波长表面结构进行了显微成像实验,观察了两类微球在空间上与样品表面分离时的成像特性.实验结果表明:在微球透镜与样品表面分离0～6μm的空间范围内,微球透镜对亚波长纳米结构仍具有分辨能力,且放大作用明显.通过实验比较,发现在浸没方式、放大率大小、成像尺度范围...     

不同因素对可调节人工晶体屈光调节力的影响

首先以Hwey-Lan Liou眼模型为基础，根据等效性原则，保持该眼模型中自然晶状体屈光度不变，对无穷远点成像。然后利用ZEMAX实现光线追迹的方法，将自然晶状体替换为可调节人工晶状体（accommodative intraocular lens，AIOL），结合对人眼成像质量影响的分析，研究了AIOL在眼内的移动度、材料、中心厚度、结构、光学面非球面性等因素对其屈光调节力的影响。结果表明:AIOL移动度对其调节力贡献最大,材料、中心厚度、结构对调节力基本无影响；具有非球面光学面的AIOL调节力相对较大。