AXXICON:把光媒介市场注塑成型

在由顾问成为总经理的Alfred Evers对公司实施新的管理之后,Axxicon再次成为世界上重要的模具供应商:经营开始有收益;目前正在为大的生产线制造商提供模具;其专业技术正得到充分应用。所有这一切都是在没有进行新机器和新技术投资的情况下取得的。     

Simulation of injection‐compression molding for optical media

A numerical simulation of a coining type of injection‐compression molding is developed. A hybrid finite element/finite difference method is employed to model the temperature and pressure fields of the process using a non‐isothermal compressible flow model. Simulation results for CD‐R molding with respect to injection pressure and mold displacement are compared with experimental observations using an optical grade of polycarbonate. The simulation shows similar trends as experimental observations on the dependence of various processing parameters such as melt temperature, mold temperature, and packing pressure. However, the mold displacement measurement does not show the effect of punch delay time as does the simulation, and needs further investigation.     

大光学各向异性液晶材料

介绍了影响液晶 Δn的因子及大 Δn液晶材料研究现状     

Polarization-Dependent Birefringence in Lithium Aluminosilicate Glass

Glass and Ceramics - The formation of polarization-dependent birefringence, apparently due to the formation of nanogratings, in the bulk of lithium silicate and lithium aluminosilicate glasses...     

Birefringence and Microstructure of Anisotropic Borosilicate Glasses

Optically anisotropic glasses were obtained by the uniaxial stretching of phase-separated borosilicate glasses in the transformation temperature range. The sign inversion of the birefringence, induced by subsequent heat treatments, was correlated with microstructure. The positive birefringence is attributed to form birefringence and the negative birefringence to "distribution birefringence" caused by the anisotropic distribution of the separated phase.     

Anomalous Birefringence in Discretely Phase-Separated Glasses

Rods of Corning code 7070 alkali borosilicate glass were stretched or compressed at 600° to 700°C before or after discrete phase separation and given a postpulling heat treatment at around 500°C. As expected, sections of the rods displayed anomalous birefringence which has been identified by Takamori to originate from anisotropy in the form and the distribution of the second-phase particles. Specimens so obtained were reheated, and the birefringence measured as a function of temperature to separate the contributions of form, distribution, and the thermal expansion mismatch (if any) between the separated phases. It is clear that the form birefringence in 7070 glass is positive for stretched rods and negative for compressed rods and decays at lower temperatures than does the distribution birefringence which has an opposite sign. TEM replica micrographs show that the distribution birefringence decays as a function of temperature mostly because of phase dissolution and the reappearance of yet another phase randomly.     

Birefringence of polyamide fibres of nonround cross-sectional from

Conclusions A method of determining the birefringence n of fibres having an uncomplicated profile (pentagonal, trilobal, or double rhombus) consists of the following: Over sections of the fibre one determines the ratio of the outer-contour dimensions — the diameterl of the fibre to its thickness d — the path over which the beam acquires the difference in speed ; the values of ,l, andl/d are averaged; and the calculation of n is carried out from the equation n = .This method has been tested on specimens of polyamide fibre prepared under identical melt flow rate conditions.Translated from Khimicheskie Volokna, No. 3, pp. 42–43, May–June, 1983.     

Birefringence study of the tricritical point in KDP

The birefringence of KDP has been measured as a function of temperature, pressure and d.c. electric field, in order to study the phase diagram in the tricritical region. The results are interpreted using a Landau-type theory.     

Structural Anisotropy and Birefringence in Microporous Glasses

Microstructural birefringence was observed by immersing microporous glass specimens in liquids with various refractive indices. The sign of the birefringence may be positive or negative depending on the base glass compositions, with the optic axis parallel to the direction of materials transport during leaching. The magnitude of the birefringence varies systematically as a function of the refractive index of the immersing liquid and depends on heat-treatment conditions of the base glass (possibly on soluble minor-phase compositions) as well as on leaching conditions (e.g. leaching temperatures and acid concentrations). This birefringence can be erased by soaking the specimens in a dilute alkali solution. Scanning electron micrographs before and after soaking indicate that the birefringence is created by the structural anisotropy of SiO₂ gels produced as decomposed deposits from the soluble minor phase within the cavity of the silica skeleton.     

Theoretical prediction on double-layer coating in wet-on-wet optical fiber coating process

A theoretical investigation is conducted on the wet-on-wet (WOW) process for double-layer resin coating of optical glass fiber. The coating process in the secondary coating die is modeled as a simple two-layer Couette flow of two immiscible fluids in an annulus with an assigned pressure gradient. The assumption of fully developed flow permits an exact solution to the Navier–Stokes equations. The solution discloses the relevant parameters in design and operation of a WOW coating applicator of optical fiber. For a given diameter of glass fiber and primary coating thickness, the secondary coating thickness is a function of the applied pressure gradient, the diameter of coating die, the viscosity ratio, and the fiber drawing speed. The influences of each of these control parameters on double-layer coating are scrutinized. A practical concept of thermal control of the coating process utilizing temperature-dependent viscosity of coating resins is explored.     

Laser Writing of Polarization-Dependent Birefringence in Sodium-Borate Glasses

Glass and Ceramics - The conditions for the formation of microdomains with polarization-dependent birefringence by a femtosecond laser beam in sodium-borate glasses with different Na2O content were...     

新ISM在线检测器系列--进一步提高光介质生产的效率

快速、紧凑及友好的用户界面是指导新一代ISM在线检测机设计的关键因素.一种成熟的方案确保了由目前的ISM系列升级为更高级的在线系列.下面是申克博士公司针对其新一代的ISM系列在使用及升级等方面的问题所做的答疑:     

Some modern optical methods for the diagnostics of processes in multiphase granular media

Modern optical methods (mainly, immersion tomography) for studying the fluid flow and heat and mass processes in a granular medium flooded with a liquid are described. The transparency of this composite medium is provided by an appropriate choice of the refractive index of the saturating liquid. This makes it possible to use all available visualization methods, including polarization interference microscopy, for obtaining the information on the processes proceeding in the medium. Applications of the method to different engineering problems are discussed.     

The Theory of High Elasticity and Birefringence of Rubbers

Abstract

On the basis of a “channel” model an attempt has been made to account for the limitation of the number of possible chain conformations in bulk elastomer. Each chain is supposed to fluctuate near its average position—the “channel”, determined by the conditions of bulk polymer formation. Then the probability of a certain chain conformation existence is reduced with the increase of its deviations from the channel axis. Chain fluctuations along the channel axis are free from any constraints because such a change of the chain conformations is not connected with the variation of its neighbours locations. In the first approximation (when the chain and the channel are divided into two parts) the calculations based on the model pointed out lead to the free energy formula deduced earlier by the author while starting from partly different assumptions. The formula fits well the experimental data for various types of deformations. Particularly, the theoretical dependence of true stress, [sgrave], on deformation has a linear form when plotted in coordinates σ/2(λ² - 1/λ) versus 1/λ(λ is the extension ratio). It permits consideration of the present study as being a theoretical basis for the Monney Rivlin formula from the molecular point of view. Calculated on the same grounds, the theoretical dependence of birefringence. Δn, on λ at uniaxial tension also has a linear form in coordinates Δn/2(λ²—1/λ) versus 1/λ in accordance with the experimental observations. However, it has a somewhat larger slope than the corresponding dependence for σ Therefore Δn/σ is found to be only slightly dependent function of λ, i.e. according to the theory presented Bruster's law should hold for rubbers only approximately.     

聚苯乙烯制品熔接线区域的双折射行为分析

基于双折射实验原理,利用偏光显微镜,运用"楔形法",测定了聚苯乙烯注塑制品熔接线区域厚度面上双折射行为分布。结果表明:距离嵌件的不同位置处,由于流动行为的差异导致了完全不同的双折射行为,根据应力-光学定律,这种行为也体现了塑料制品的分子取向、残余应力的分布情形。     

Birefringence of injection-molded glassy polymers during relaxation and recovery

Birefringence measurements have been made on six glassy polymers during stress–relaxation and recovery experiments at temperatures below T_g. Of the six polymers tested only one pair, poly(ethylene terephthalate) and a glassy polyamide (“Trogamid”), show a strong mutual resemblance in the behavior of birefringence under these conditions. The results are discussed with reference to molecular structure, and, although detailed interpretations are not offered, it is observed that the behavior is less complex for polymers which possess their most polarizable groups in the main chain or attached rigidly to it than for those polymers having polarizable side groups with relaxations which do not involve the main chain. All six polymers have been tested in injection-molded form, and the possible consequences of this are considered. The major differences observed to occur between the different materials do not appear to be related to processing, however, and some results obtained using specimens prepared in other ways are also presented to illustrate this.     

On the pressure drop prediction of filter media composed of fibers with bimodal diameter distributions

In addition to collection efficiency, pressure drop is the most important characteristic of a filter medium. While there are numerous analytical expressions available for predicting the pressure drop of the filters made up of fibers with a unimodal fiber diameter distribution, there are not enough studies dedicated to filters composed of fibers with a bimodal (or multimodal) fiber diameter distribution. In this work, the pressure drop per unit thickness of filters made of bimodal fiber diameters is calculated by solving the Navier-Stokes equations in a series of 2-D geometries. These results are used to find the unimodal equivalent diameters of each bimodal filter that could be used in the existing expressions for calculating pressure drop. In agreement with the work of Brown and Thorpe [Brown, R.C., Thorpe, A., Glass-fiber filters with bimodal fiber size distributions. Powder Technology 118 (2001) 3-9.], it was found that the area-weighted averaging of the fiber diameters in a bimodal filter provides a relatively good estimation of its equivalent unimodal fiber diameter. We, however, noticed that in such an averaging the error percentage in the pressure drop prediction is sensitive to the fiber diameter ratios as well as the fraction of each fiber diameter in the bimodal filter. We, therefore, obtained a correction factor for the estimation of the unimodal equivalent diameters as a function of fiber diameter ratio and their number fractions.     

Preparation of optical media with NIR luminescent Bi+ impurity centers by ion exchange

Single crystal of TlCl was doped with NIR photoluminescent univalent bismuth cations by prolonged immersion in liquid bismuth metal. The ion exchange Tl⁺ + Bi⁰ ↔ Tl⁰ + Bi⁺ at the crystal surface with subsequent Bi⁺ migration to the bulk are expected to drive the doping process. Contrary with Bi-doped TlCl crystals, grown by Bridgman method, the ion exchange does not produce the additional nonluminescent bismuth-containing centers. The investigation of photoluminescence emission and excitation spectra lead to the conclusion, that Bi⁺ is the main NIR emissive center in Bi-doped TlCl.     

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.