Controlling subsurface damage in neodymium-doped phosphate glass

We investigate the removal mechanism of neodymium-doped phosphate glass dominated in loose abrasive grinding and bound abrasive grinding. Moreover, we investigate the surface roughness and subsurface damage change with optical fabrication parameters, such as different spindle speed, load and abrasive size under different grinding processes in details. For a range of experimental conditions, we find that fracture is the principal removal mechanism for loose abrasive grinding, while plastic scratching is the dominating mechanism for bound abrasive grinding. The load has more influence on subsurface damage for bound abrasive grinding than for loose abrasive grinding. However, the spindle speed has different effect on subsurface damage produced with loose abrasive grinding and bound abrasive grinding. Moderate spindle speed and low load is preferred to produce smaller subsurface damage for loose abrasive grinding. Moreover, higher spindle speed and lower load are preferred to plastic scratching for bound abrasive grinding. Bound abrasive grinding produces 4 times lower surface roughness and 3 times lower subsurface damage than loose abrasive grinding.     

Free-form lens design for wide-angle imaging with an equidistance projection scheme

An algorithm of free-form lens design is presented that can realize wide-angle imaging in conjunction with conventional imaging devices. The wide-angle image obtained through the free-form lens and the camera is not affected by distortions. The formula for the free-form lens surfaces is derived. The surface profile of the free-form lens can be generated through solving a differential equation expressing the camera-viewing angle as a function of the angle of incidence on the free-form lens surface. The surfaces preserve a linear relationship between the angle of incidence of light onto the surface and the angle of refraction into the imaging device.     

Prediction of spinodal wavelength in continuously cooled metallic liquid

The spinodal decomposition of a deeply undercooled metallic liquid Zr_41.2 Ti_13.8Cu_12.5Ni₁₀Be_22.5 between 800 and 700 K is analysed in the framework of the theory of Cahn and Hilliard for continuous cooling, and the wavelength with maximum amplification is predicted, using as input parameters thermodynamic values gained in experiments. Electron microscopical studies show the microstructure of glass forming alloys Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5. The as‐cast material exhibits a two phase mixture of amorphous regions with different compositions. Evidence for spinodal decomposition is given, and the computed maximum‐amplitude wavelength corresponds well with the one found in the experiments.     

Luminescence behavior of Tb ions in transparent glass and glass-ceramics containing CaF2 nanocrystals

Transparent glass-ceramics have been fabricated by heat treatment with 1.0 mol% Tb₂O₃-doped 45SiO₂-20Al₂O₃-10CaO-25CaF₂ aluminosilicate glass. The precipitated crystalline phase in the glass-ceramics is CaF₂ nanocrystals with a size of 15-27 nm and dispersed in the amorphous phase. Both photo- and radioluminescence measurements show that the increase of Tb³⁺ 545 nm line intensity by a factor of 4 and 3.5 is obtained in glass-ceramics with respect to the as-made glass, respectively.     

Vibro-acoustic behaviour of laminated double glazing enclosing a viscothermal fluid cavity

This paper presents a new numerical model to investigate the vibro-acoustic behaviour of two laminated glass plates enclosing a thin viscothermal fluid cavity. The aim of this work is to develop an original five layer (two skins plies, two adhesive films and a core ply) laminated plate finite element by mixing Kirchhoff and Mindlin plate’s theory. The formulation is based on the theory that accounts for the transverse shear in the adhesive films and in the core. The acousto-elastic model is established in dimensionless appropriate form including the effects of viscosity and thermal conductivity of fluid and by taking into account the fluid-structure interaction. The discretization of the energy functional by finite element method gives after minimisation a symmetrical coupled matrix system in which the acoustic matrices are frequency dependent. Therefore, an iterative procedure is derived to determine the eigenmodes of the coupled system. The modal approach is adopted to determine the vibro-acoustic system’s response. Then, the validation of the new laminate finite element model is achieved by comparing the sandwich plate results against data obtained from literature. Subsequently, predicted responses, such as the vibration transmissibility and the transmission loss of the coupled system, for a given laminated double glazing under an imposed homogeneous pressure are presented and discussed. Numerical results show the importance of both lamination and viscothermal fluid effects on double glazing vibro-acoustic behaviour.     

Different shapes of tracks in phlogopite, biotite and soda lime glass

Etched track opening geometries in Biotite, Phlogopite and soda-lime glass irradiated with swift heavy ions [¹⁹⁷Au(11.64 MeV/n), ¹³⁶Xe(11.56 MeV/n), ⁵⁸Ni(11.56 MeV/n)] at different angle of incidence have been studied using appropriate chemical etching technique. Different geometries (Hexagonal, irregular polygon, triangular in case of Biotite and Phlogopite, and circular & elliptical in case of soda lime glass detector) of heavy ion tracks are reported in the present investigations using optical microscope. The different shapes of these heavy ions track geometries are found to be related with various target-projectile parameters (viz: type of projectiles, energy, stopping power, angle of incidence of the projectile, density of defects and its reactivity with etchant, etching conditions and chemical structure of the detectors). The dependence of different shapes of heavy ion tracks in isotropic and anisotropic medium on the variation of radiation damage densities along the ion trajectories have also been discussed in the present paper.      

非水滴定测定烟叶中烟碱含量实验的微型化

研制了一种微型滴定装置,利用该装置(WD-COⅡ型微型滴定装置)对烟叶中烟碱含量进行非水滴定,通过数理统计方法将微型滴定管与常规滴定管的平行测定结果进行了比较,得到相同样品的一对非常接近的测定结果。证明新型微量滴定管具有较好的操作性能和精密度。     

石英玻璃低能质子辐照损伤动力学研究

地面模拟研究了JGS3光学石英玻璃在真空、热沉和能量低于200keV的低能质子辐照下表面光学性能变化的基本规律．并建立了辐照损伤色心演化的动力学唯象模型。试验结果表明．大通量低能质子辐照对石英玻璃表层具有明显的表面损伤效应。随着辐照吸收剂量的增加,光密度变化先以线性规律迅速增加．加进一步增加时逐渐呈现饱和趋势;采用较高能量辐照作用后光密度变化出现饱和趋势的拐点提前,且饱和数值降低。根据对试验结果的分析,建立了低能质子辐照下石英玻璃色心演化的动力学模型．并给出了光密度变化的表达式。采用模型结果进行数学模拟,模拟曲线与试验结果曲线相似。因此所建立的动力学模型可以用来定量描述低能质子辐照下石英玻璃光学性能随辐照吸收剂量的变化规律。     

控制液晶器件产生的程控透镜和微透镜阵列

研究了计算机程控光学器件的性能。通过对液晶空间光调制器进行电寻址控制,得到了振幅模式、二进制相位模式和连续相位模式的计算机程控透镜和程控微透镜阵列。实验结果和计算分析都表明,连续相位模式的程控透镜具有较好的聚焦性能和光效率。程控微透镜阵列的优点是阵列中的每一个微透镜都可以单独控制,可以得到所需要的阵列形式。实验给出了一个由这样的微透镜阵列产生的去掉了中心4×4阵列的8×8光斑阵列样式。还给出了利用程控透镜来方便有效地演示和研究透镜的像差方法。由计算机控制空间光调制器得到的光学器件虽然具有极大的灵活性,但是由于空间光调制器的像素的尺寸影响了它的精细程度,限制了它的应用。     

整体X光透镜性能实验研究

利用高计数率探测器和低功率光源,在大的能量范围内,同时测量了整体X光透镜的传输效率和焦斑直径与能量的关系。实验结果表明：透镜的焦斑直径随着能量的升高而减小;对04-5-10-5透镜而言,在高于5．8keV的能量范围内,透镜的传输效率随着能量的升高而降低,在低于5．8keV的能量范围内,透镜的传输效率随着能量的升高而增加。通过测量不同能量的X射线在透镜会聚光束中的空间分布,研究了短出口焦距透镜的光晕现象,光晕会导致透镜焦斑直径增大和传输效率测量值的增加。利用轴向扫描法研究了整体X光透镜出口焦距和能量的关系,实验结果表明：会聚透镜的出口焦距随着X射线能量的升高而增加。