梯度光学功能玻璃研究进展

梯度折射率(GRIN)玻璃是指具有梯度折射率分布的光学功能玻璃,其在光学及光电学领域中具有广阔的应用前景.介绍了GRIN玻璃的形成原理及分类,综述了GRIN玻璃的制备技术及发展现状,讨论了它们各自存在的问题,提出了今后GRIN玻璃的研究方向.     

Finite Element Calculation of Refractive Index in Optical Glass Undergoing Viscous Relaxation and Analysis of the Effects of Cooling Rate and Material Properties

In this research, a methodology based on a numerical simulation model is presented to predict refractive index change introduced to two low T_g optical glasses, namely, P-SK57 and P-LASF47, by cooling. To model the structural relaxation behavior of glass around glass transition temperature, the Tool–Narayanaswamy–Moynihan (TNM) model is used. In addition, the fictive temperature of the glass samples during cooling is discussed. The effect of cooling rate on the fictive temperature of the glass samples is also presented. This study demonstrated that finite element method is capable of predicting refractive index of optical glass undergoing viscous relaxation. The simulated results in this study confirm that a higher cooling rate leads to a lower refractive index and a larger variation of refractive index in glass optics. The results also suggest that for glass, materials with high thermal conductivity and low heat capacity are preferred for compression molding process.     

Change in Refractive Index of a Borosilicate Glass Fiber Annealed Below the Glass Transformation Temperature

Glass fibers pulled from multihole bushings can have a slight difference in thermal history that causes a distribution in the refractive index that can be narrowed by annealing the fibers. The kinetics for the initial stage change in refractive index for fiber annealed between 300° and 500°C are best described by a second-order reaction with an activation energy of 120° 17 kj/mol. The improved uniformity in refractive index for annealed fibers is indicated by a decrease in the half-height width of the optical transmission versus temperature curve for glass fiber immersed in a liquid. The standard deviation in the refractive index of glass fibers with a bimodal distribution in diameter decreases from 8 × 10^-4≤0.0002 to 4 × 10^-4 0.0002 after the fibers are annealed at 400°C for 1 h.     

GexAs20Se80-x玻璃的化学组成对结构和物理性质的影响

本文制备了一系列Ge_xAs₂₀Se_80-x硫系玻璃,旨在了解化学组成和平均配位数对其结构和物理性质的影响。采用棱镜耦合法测量玻璃的折射率,采用分光光度法测量玻璃透射率并根据透射谱得到玻璃的光学带隙。研究发现,当玻璃组成满足完全化学计量配比之前,随着Ge含量的增加,玻璃的折射率随之减小,而光学带隙随之增大。通过测量拉曼光谱并对其进行分解,发现随着玻璃化学组成的改变,其结构中异极键相对数量的变化是合理的;而同极键的数量则与光学带隙和折射率的变化密切相关,主要是由于同极键形成的带尾可以降低玻璃的光学带隙。另一方面,玻璃的各个结构单元及物理性质在满足完全化学计量配比的玻璃组成上出现转变行为,由此可以断定,Ge_xAs₂₀Se_80-x硫系玻璃的化学组成主导着其结构和物理性质。     

Shelyubskii Method of Studying Phase Separation in the System Li2O-SiO2

The experimental performance of the Shelyubskii method has been improved and applied to studying the change in glass homogeneity of the system Li₂O-SiO₂ caused by phase separation. Binodal temperatures obtained by this method are in good agreement with literature data obtained by an alternative method. The Shelyubskii method is capable of monitoring changes in glass homogeneity from a change in refractive index of the material with an accuracy of Δn×10⁻⁵.     

Optical fiber extrinsic refractometer to measure RI of samples in a high pressure and temperature systems: Application to wax and asphaltene precipitation measurements

An optical fiber extrinsic sensor for measurement of changes in the refractive index of liquids confined in chambers for high pressure and temperature experiments is described. One head sensor composed by two fibers is fixed in front of a high pressure and temperature cell filled with the sample. The operation principle is based in the reflectivity dependence in the refractive index of the glass–liquid interface. Excellent results and a sensitivity of 10⁻⁵ RI were obtained for pure liquids. The applicability of the sensor is demonstrated following the changes in the refractive index for pure liquids at different pressure and temperatures and by measuring the asphaltenes and wax precipitation in crude oils under pressure. The extrinsic probe designed for refractive index measurement proves to be a reliable tool for measuring heavy organics deposition in crude oils under high pressures and temperatures where the sample to be measured is not very accessible.     

注塑成型光学制品折射率分层模拟与实验研究

与玻璃制造光学制品相比,高分子注塑光学制品具有质量轻、易加工、抗冲击性好等优点,在航空航天、精密透镜等高端领域得到广泛应用。然而受注塑过程复杂压力场、温度场的耦合作用,注塑透明制品折射率通常呈非均匀的分布,存在角偏差、光畸变等光学缺陷。因此,开展注塑工艺对其折射行为影响的模拟与实验研究,对实现折射率可控光学制品的成型具有重要意义。基于Hele Shaw注塑理论和Lorentz Lorenz物理光学理论,构建了注塑光学制品厚度方向折射行为分层预测模型,开发了相关模拟程序,基于自主研发的注塑模软件Z-Mold实现了注塑过程与折射率分布的一体化模拟。以聚碳酸酯注塑平板件为例,利用Brewster法对折射率模拟结果进行了验证。该方法成功应用到神舟系列航天舱外服面窗的研制。     

Intrinsic high refractive index polymers

As the ubiquity and complexity of optical devices grows, our technology becomes more dependent on specialized functional materials. One area of continued interest is in high refractive index polymers as lightweight, processable and inexpensive alternatives to silicon and glass. In addition to a high refractive index, optical applications require these polymers to be transparent and have a low optical dispersion. Both nanocomposite and intrinsic high refractive index polymers offer particular advantages and disadvantages. While nanocomposite high refractive index polymers have refractive indices above 1.80, the nanoparticle type, content and size can negatively affect storage stability and processability. Alternatively, intrinsic high refractive index polymers are prepared by introducing an atom or substituent with a high molar refraction into a polymer chain; the resultant polymers are easier to store, transport, tune and process. Polymers containing aromatic groups, halogens (except fluorine), phosphorus, silicon, fullerenes and organometallic moieties have all shown significant promise. Many factors can affect intrinsic high refractive index polymer performance including molecular packing, molar volume, chain flexibility and substituent content. This mini‐review summarizes the principles behind and recent developments in intrinsic high refractive index polymers. © 2014 Society of Chemical Industry     

High-precision molding simulation prediction of glass lens profile for a new lanthanide optical glass

Precision glass lens molding (PGLM) is a recently developed method for fabricating glass optical components with high precision in large volumes. Lanthanum optical glasses are extensively used as optical materials owing to their superior optical properties, such as high refractive index, low dispersion, and high transparency. However, the transformation temperature of currently available high refractive index glass is generally above 650 °C and poses a challenge in manufacturing ultra-hard molds, durable coatings, and high-temperature molding equipment using PGLM. In this study, a preparation method for obtaining high refractive index, low -melting -point lanthanide optical glass (B-ZLaT198) used in PGLM was developed to reduce the transformation temperature. The developed method also characterizes the glass refractive indices and thermal-mechanical properties. To achieve the high-precision prediction of a molding shape in a simulation, a viscoelastic constitutive model of glass was established based on a micro-deformation uniaxial compression creep test. Moreover, by solving the Tool-Narayanasway-Moynihan model parameters based on the specific heat capacity fitting of optical glass at different heating and cooling rates, the input parameters of the structural relaxation model (SRM) for simulation prediction of aspheric glass lens profile deviation in the annealing stage were obtained. Finally, the profile deviation of the aspheric lens was predicted using a finite element model simulation. The results showed that the simulation’s predicted profile of an aspheric lens using the SRM model was in good agreement with that of experimental molding profile. In addition, using the SRM provided a higher prediction accuracy than that of the thermal expansion model in the annealing stage. Adopting the SRM was necessary for the annealing simulations of molding pressing and also verified the accuracy of the proposed viscoelastic characterization method for calculating the thermomechanical parameters of optical glasses.     

Optical and mechanical properties of optically transparent poly(methyl methacrylate) composites

Highly transparent poly(methyl methacrylate) (PMMA) composites have been made by carefully matching the refractive index of the glass fiber reinforcement with the PMMA matrix. Composites containing 10.4 vol% glass fibers and 0.68 mm in thickness had an overall optical transmission of 92%. The transparency of the composites is temperature dependent because of the different temperature coefficients of refractive index for the glass fiber and PMMA. The tensile strength of the composites at room temperature was twice that of pure PMMA and decreased with increasing temperature, as predicted by the rule of mixtures.     

Experimental investigation on optical constants of aerosol particles

Based on the experimental infrared spectral transmittances, an inverse model for determining the optical constants of aerosol particles is presented in this paper. Combined with the Mie theory and Kramers–Kronig (K–K) relations, the complex refractive indices of the aerosol particles are retrieved by the spectral transmittance distribution of a cloud of aerosol particles in potassium bromide (KBr) pellets. Particular attention is given to the unique value problems of the complex refractive index. According to calculation and analysis, the uniqueness range of the complex refractive index is obtained. The complex refractive indices of SiO₂, Fe₂O₃, CaSO₄, Al₂O₃ particles or their mixtures with different volume fractions are obtained. At the same time, the retrieved effective refractive indices of mixed particles are compared with those from effective medium theory. Good agreement is obtained between the inverse simulation results and the results from effective medium theory. Finally, the complex refractive index of aerosol particles collected in China is determined by the inverse model used in the present work.     

Single-scattering properties of tri-axial ellipsoidal mineral dust aerosols: A database for application to radiative transfer calculations

This paper presents a user-friendly database software package of the single-scattering properties of individual dust-like aerosol particles for application to radiative transfer calculations in a spectral region from ultraviolet (UV) to far-infrared (far-IR). To expand the degree of morphological freedom of the commonly used spheroidal and spherical models, tri-axial ellipsoids were assumed to be the overall shape of dust-like aerosol particles. A combination of four computational methods, including the Lorenz–Mie theory, the T-matrix method, the discrete dipole approximation, and an improved geometric optics method, was employed to compute the phase matrix, extinction efficiency and single-scattering albedo of ellipsoids with various aspect ratios and sizes. The scattering property database was developed for 42 particle shapes specified in terms of two aspect ratios, 69 refractive indices and 471 size parameters. Additionally, accompanying software, based on interpolation, was developed to provide the single-scattering properties for user-specified aspect ratios, refractive indices and size parameters. The software package allows for the derivation of the bulk optical properties for a given distribution of particle microphysical parameters (i.e., refractive index, size parameter and two aspect ratios). The array-oriented single-scattering property data sets are stored in the NetCDF format.     

离子交换玻璃平板和圆棒中的氧化钠浓度和折射率分布

用有限差分法解扩散系数依赖于浓度的扩散方程。将计算的离子交换玻璃平板和圆棒中的氧化钠浓度和折射率分布分别与用电子探针和干涉显微镜测量的结果做了比较。即使玻璃中离子的互扩散系数还取决于长的离子交换时间,若通过选择某一时间离子交换玻璃中离子的互扩散系数,去计算其他时间离子交换玻璃中的浓度和折射率分布,可以使计算值和测量值之间的误差降低到尽可能小。在计算机模拟的基础上,讨论了计算参数和玻璃棒半径大小对获得最佳折射率分布时的离子交换时间的影响。     

Evaluation of high temperature polymers in nanolayered films and gradient refractive index (GRIN) lenses

A new polymer nanolayer gradient refractive index (GRIN) system with more robust thermal stability because of incorporation of a high glass transition temperature polyester, OKP4HT, was demonstrated. A combination of extruded nanolayered GRIN film systems, comprised of five unique polymer materials, were combined to produce laminate optics comprised of a large internal refractive index gradient distribution, n = 1.445 – 1.630, without degradation of optical transmissive properties. The optical performance of a series of varied magnitude GRIN lenses, ranging from Δn = 0 to 0.185, was evaluated. Increasing the lens refractive index range resulted in decreased optic sphericalaberrations that followed analytical predictions. An analytical approach was reported to correlate the polymer material upper service temperature (UST) to the onset of polymer material loss modulus as measured by DMTA. Thermo‐optical interferometry measurements of irreversible lens deformation confirmed the lenses UST at 125°C for the OKP4HT/PC system as compared to 75°C for a PMM/SAN17 system. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42741.     

The evolution and generation of nanosurfaces and their microcontact mechanism in glass-embossing process

Glass-embossing technology has attracted great attention due to its promise of low-cost and environmentally conscious fabrication of well-defined and controllable surfaces and nanostructured devices. The embossed surface quality of glass structures is a very important index for optics. However, the evolutions of nanosurfaces and their microcontact mechanism during glass-embossing process have not been deeply and comprehensively investigated. Here, we studied the surface morphology evolution of optical glass under different processing conditions using a tungsten carbide surface plate with nanoscale roughness as the mold. The light transmittances of different embossed glasses were detected by an ultraviolet spectrophotometer. The flow deformation and microcontact mechanism of glass-supercooled liquids were revealed during glass-embossing process. The result showed that the rough optical glass can successfully replicate the nanoscale smoothness of the tungsten carbide template without grinding or polishing. On the basis of the previous study, the glass-surfaced structures from nanoscale to macroscale are fabricated. This work provides better understanding for the evolution of nanosurfaces and the fabrication of nanostructured optics during glass-embossing process.     

Preparation and properties of optically transparent,pressure-cured poly(methacrylate) composites

The objective of this work was to develop optically transparent glass fiber reinforced poly(methyl methacrylate) (PMMA) composites by matching the refractive index of the glass fiber reinforcement to that of the PMM, A matrix, thereby minimizing the quantity of light which is normally scattered and reflected at the interface of dissimilar materials. A pressure curing process is described for preparing composites 10 by 15 by 0.6 cm thick and containing up to ∼ 35% glass fiber. By curing at 65°C under 6.9 MPa N₂ for 18 H, composites have been produced with optical quality surfaces and flexural strengths more than seven times that of commercial PMMA of the same thickness. A transparent composite containing 10.4 vol% of 13 μm diameter fiber had an 84% optical transmission (92% maximum for PMMA) at 600 nm and 25°C.     

温度对OPC装置在线检测颗粒物的影响

以球形SiO2颗粒为研究对象搭建高温测试实验台,用光学粒子计数器(OPC)测定了25?800℃下的颗粒数及其累计分布,并进行扫描电镜(SEM)和X射线衍射(XRD)分析,研究了高温对颗粒物在线检测结果的影响。结果表明,随加热温度升高,SiO2颗粒的粒径先变小后增大再变小,但颗粒物形状未发生变化;XRD衍射峰强度整体变弱,2θ?25.5o处的衍射峰宽化并移动,晶胞体积先增大后变小。根据SiO2晶胞体积与晶体介电常数的关系可排除加热使颗粒物粒径变化,温度升高导致SiO2颗粒晶体内部结构变化、晶体折射率变化,使测量结果存在2?3个粒径通道的误差,影响测量精度。     

Chalcogenide glasses with embedded ZnS nanocrystals: Potential mid‐infrared laser host for divalent transition metal ions

Chalcogenide glasses (ChGs) containing II‐VI chalcogenide (ChG) nanocrystals such as ZnS/Se have recently been intensively studied as promising mid‐infrared nonlinear optics and laser materials, yet preparation of pure‐phase II‐VI nanocrystals embedded in ChGs via controlled crystallization is still very challenging. In this study, a new system of ChGs and glass ceramics (GCs), viz., (100?x)As₂S₃–xZnSe (x = 0 ~ 30 mol%), is synthesized, and its physical and optical properties including density, molar volume, microhardness, glass transition temperature, glass network structure, transmission, and refractive index are comprehensively characterized. Significantly, it is initially demonstrated that pure ZnS nanocrystals can be precipitated in GCs simply by a thermal treatment process. The composition and thermal treatment temperature dependencies of crystallization are studied using X‐ray diffraction spectroscopy, and the morphology of the nanocrystals by high‐resolution transmission electron microscope. The ChG GCs with embedded ZnS nanocrystals retaining good transparency can be a potential host laser material for divalent transition metals (e.g., Cr²⁺/Fe²⁺, etc.), and thus used for ultrabroadband tunable continuous or ultra‐short‐pulsed mid‐infrared fiber lasers.     

Sol–Gel Synthesis of Doped Vitreous Materials with the Use of Modified Aerosils

A novel variant of the sol–gel synthesis of silica glasses and optical composites containing transition-metal ions and nanoparticles is developed. Xerogels and glasses containing 10- to 46-nm particles are prepared with the use of aerosils modified by chromium oxide. The structural and physicochemical properties of chromium oxide–modified silica samples are investigated by X-ray powder diffraction, differential thermal analysis, thermal gravimetric analysis, and IR spectroscopy. The optical properties of transparent samples are examined using the transmission spectra and the refractive index distribution over the cross section of the xerogel preform. Xerogels and glasses containing nanoparticles of metallic copper and Cu _x Se are formed in the tetraethoxysilane–aerosil–copper nitrate system. An analysis of the optical properties of the nanocomposites demonstrates that SiO₂ : Cu _x Se nanocomposites can be used as passive Q switches.     

BaO-TiO2-SiO2系统高折射率光学玻璃

以BaO-TiO2-SiO2-RmOn系统为研究对象。在SiO2质量百分含量分别为15%、12%、10%时,改变BaO/TiO2的比值,得到一组高折射率光学玻璃。测试玻璃的密度、折射率、阿贝数和紫外到红外波段的透过率等物化性质,研究密度和折射率与组成的关系及影响阿贝数、透过率大小的因素。结果表明,密度随BaO/TiO2比值的增加先增加后减小,折射率随BaO/TiO2比值的增加而减小,折射率和密度变化趋势不一致。TiO2含量是影响阿贝数和透过率大小的主要因素。