A Method for the Optical Characterization of Thin Uniaxial Samples

An optical characterization procedure for small fragments of uniaxial materials is described involving the simple use of crossed polarizers with one polished face of the material. The reflectance at a fluid-uniaxial slab boundary beyond, but near, the critical angle of incident light is examined for linear incidence polarization using an orthogonal output polarizer. It is found that, as the crossed incident and output polarizers are rotated together, there are, for a given angle of incidence, particular polarization angles for which the reflectivity is a minimum. These angles give information on the optical tensor of the crystal under study. Further the intensity of the reflected light, for incidence angles beyond critical with the input and output polarizers crossed, has as a function of the incident polarization angle an oscillatory form which, when fitted to theory, can also yield the full uniaxial tensor of the material under study. This is confirmed experimentally for a thin single crystal of calcite with one polished face.     

运用ASAP光学软件模拟单轴晶体的锥光干涉

为了模拟不同光轴取向、光束发散角、晶体厚度或入射波长等参数下的单轴晶体锥光干涉,在 ASAP中定义起偏器、晶体、检偏器和接收屏的几何形状和光学特性,产生一组锥状高斯光束并设置其相干性和波动性,进行光线追迹、计算并显示接收屏上的干涉场能量分布。所得模拟结果表明,光轴与晶体表面垂直时,干涉条纹是 1组以光轴为圆心且被十字分割的内疏外密、明暗相间的同心圆环;平行时,是 2组分别以光轴的平行和垂直方向为对称轴的、内疏外密、明暗相间的双曲线;既不垂直也不平行时,条纹特征因光轴取向而异;当增大发散角、晶体厚度或减小波长时,干涉条纹都向内移动且条纹数增多,反之亦然;起、检偏器正交时的干涉条纹都和它们平行时的条纹互补。     

DCTA对KDP晶体的快速生长与光学性能的影响

环己二胺四乙酸(DCTA)作为一种新型添加剂被加入到KDP晶体生长溶液中。采用“点籽晶”快速生长技术, 在掺杂100×10^-6 DCTA的饱和溶液中, 生长了KDP晶体, 生长速度达20 mm/d。研究了这种新型添加剂DCTA对快速生长的KDP晶体的生长习性和光学质量的影响, 并与常用添加剂EDTA的影响效果进行了对比。研究发现, 在KDP晶体生长溶液中添加100×10^-6 DCTA使生长溶液的亚稳区宽度提高了约10℃, 晶体(100)面的生长速度提高了3~10倍; 生长出的晶体在紫外波段的透过率上升了2~8倍, 晶体内部的光散射大大减轻, 激光损伤阈值也有所提高。添加剂DCTA对KDP晶体生长及性能的改善作用比同等浓度的EDTA更加显著。     

Optical Mode Characterization of the Configuration of a Thin Ferroelectric Liquid Crystal Cell Under an Applied Electric Field

Abstract

It is possible to probe directly the optic dielectric tensor configuration within a thin (about 3·5 μm) smectic layer of a ferroelectric liquid crystal (FLC) by the propagation of prism-coupled leaky Fabry-Perot optic modes. Incident monochromatic polarized light couples into the resonant modes of the system which are then observed as sharp dips in the reflected signal at specific incident angles. This work has shown that the FLC has an optic tensor profile which is consistent with the chevron formation of the smectic layers observed in X-ray scattering measurements. Also it is shown that under the application of a low d.c. applied field the optic dielectric tensor configuration distorts in a manner consistent with the retention of the chevron structure up to fields of about 10⁶ Vm^?1.     

大尺寸Ce:Lu1.6Y0.4SiO5闪烁晶体的生长和光谱特性

采用中频感应提拉法生长出尺寸为φ60mm×110mm的Ce:Lu1.6Y0.4SiO5(LYSO)晶体,与LSO晶体相比,LYSO晶体的优势是提高了晶体质量、降低了熔点和原料成本等.在室温下测试了LYSO晶体的透过光谱、激发光谱和发射光谱,结果表明Y的加入使LSO晶体的吸收边向短波方向偏移. Ce3+的4f1→5d1跃迁吸收导致紫外区产生三个吸收带.发射光谱具有Ce3+典型的双峰特征,经Gaussian多峰值拟合,双峰395nm和418nm归属于Cel发光中心,而435nm的发光峰与Ce2发光中心有关.     

新型非线性光学晶体MnHg(SCN)4的合成、结构及表征

合成了配合物晶体ＭｎＨｇ（ＳＣＮ）４。用Ｘ射线四确定了此配合物的晶体结构。用元素分析、红外光谱、紫外一可见光谱以及ＴＧ－ＤＴＡ热分析对其进行了化学表征。测量了不同温度下此配事物晶体在纯水中的溶解度。以尿素为标准样品,用１０６４ｎｍ被劝锁模６０ｐｓ脉冲Ｎｄ：ＹＡＧ激光为入射基频光测得此晶体的倍频光强度为尿素的５０倍。因此,ＭｎＨｇ（ＳＣＮ）晶体是一种新的非线性光学材料。     

向列型热致液晶聚酰胺的结构表征

采用傅立叶红外光谱仪（IR）、广角X射线衍射仪（WAXD）、热台偏光显微镜（POM）及扫描电子显微镜（SEM）对所合成热致液晶聚酰胺进行了结构表征。IR谱图显示了该聚合物为半刚性结构,与所设计的分子结构相一致;WAXD曲线显示处于液晶态的聚合物在2θ=20°左右有一弥散的峰,表明该液晶聚合物为向列型液晶结构;POM观察...     

大尺寸PWO:(Sb,Y)晶体光谱特性的表征研究

报道了用改进的Bridgmam法生长的大尺寸PbWO4:(Sb,Y)晶体的光谱特性的表征研究.通过对依次切自大尺寸PbWO4:(Sb,Y)毛坯晶体的籽晶端、中间部位和顶端三块晶体(-23mm×23mm×20mm)的透射光谱、X射线激发发射光谱、紫外激发与发射光谱、发光衰减寿命、光产额和辐照损伤等方面的光谱性能测试,结果表明,Sb、Y双掺杂能显著改善PbWO4晶体的光谱性能,使晶体在短波330-420nm范围的透过率明显提高,光产额增加,抗辐照能力增强.但从籽晶端到顶端的性能存在一定的差异,说明大尺寸的PbWO4:(Sb,Y)晶体的均匀性还有待提高.     

新型紫外非线性光学晶体KNa5Ca5(CO3)8的合成、表征及性能的研究

采用水热法合成出一种新型碳酸盐非线性光学晶体材料KNa₅Ca₅(CO₃)₈, 该晶体属于六方晶系, 空间群为P63mc, 晶胞参数为a=b=1.00786(4) nm, c=1.26256(8) nm, Z=2。其晶体结构可以看作是由站立的[CO₃]基团连接相邻的两个[CaCO₃]_∞层, 从而沿[010]方向形成了四种不同类型的孔洞, 在这些孔洞中填充着K、Na 和[Na_0.67Ca_0.33]原子。KNa₅Ca₅(CO₃)₈晶体的粉末倍频效应为KDP的1.2倍, 且能够在可见光区实现相位匹配。紫外-可见-近红外漫反射光谱测试结果表明其晶体具有较大的光学带隙, 大概为5.95 eV, 是具有潜在应用前景的紫外非线性光学晶体材料。此外, 第一性原理的计算结果表明, 晶体的非线性系数主要来源于CO₃基团。     

PbMoO4晶体光学性质的第一性原理研究

基于密度泛函理论(DFT)的广叉梯度近似(GGA)下的平面渡超软赝势法,计算了PbMoO4晶体的电子结构和光学性质.结果表明,介电函数的虚部与光电导的实部、复数折射率、光吸收谱的峰值位置有着一一对应的关系,并且可以从电子态密度图中的价带和导带间的电子跃迁得到合理解释.     

纳米尺度栅线结构的线边缘粗糙度分析和表征

为了对线边缘粗糙度(LER)和线宽粗糙度(LWR)进行分析和表征,采用电子束光刻工艺和感应耦合等离子体刻蚀工艺制备了两种纳米尺度栅线结构,用扫描电子显微镜(SEM)对所制备结构进行了检测和定性分析.基于离线SEM图像分析法提取了纳米栅线结构的线边缘轮廓.将所提取的线边缘轮廓视为随机信号,分别采用均方根偏差σ、偏斜度Sk、峭度Ku、高高相关函数和功率谱密度函数表征了LER/LWR的幅度特征、形状特征和空间特征,研究了LER/LWR各参数从光刻图形到刻蚀图形的变化,实现了LER/LWR的定量分析和表征.     

Image Intensity at the Edge of a Straight Edge Object

Abstract

We consider the value of the intensity image at the geometrical position of a general, flat, straight edge object. We adopt a Fourier optical transfer function approach and obtain, rigorously, analytic expressions for the cases of coherent, incoherent and equal aperture, partially coherent imaging. Aberration-free, circular pupils are considered and the analytic results are found to agree with earlier numerical calculations. We also obtain expressions for the intensity gradient at the edge.     

液晶显示器颜色局部特性化研究

目的在液晶显示器上小范围内精确地控制颜色的显示。方法实验选择国际照明委员会推荐的5个基本颜色中心,使用线性插值的方式在各颜色中心小范围内建立三维查找表,实现小范围内精确控制液晶显示器颜色显示的目的。结果该方法对L*,a*,b*的控制精度分别为0.05,0.08和0.03,对色差的控制精度是0.18ΔEab个色差单位。结论使用小范围内建立三维查找表的方式可以实现小范围内更精确显示颜色的目的,为在液晶显示器上实现颜色视觉评价提供特性化基础。     

ZnO薄膜的晶体性能的分析

在硅基上制备出了c轴取向高度一致的ZnO薄膜 ,这将有可能成为新型GaN单晶薄膜的过渡层。对ZnO薄膜的晶体性能进行了分析 ,研究不同衬底和不同衬底温度对ZnO薄膜的结晶状况的影响 ,并着重用TEM研究了硅基ZnO薄膜的晶体性能。     

Determination of the Director Alignment in a Ferroelectric Liquid Crystal Device by Observation of Optical Modes

Abstract

By observing the angular dependence of the reflectivity of a ferroelectric liquid crystal (FLC) cell fabricated from glass pyramids with 60° evaporated SiO aligning layers it has been possible to sensitively probe the configuration of the optical dielectric tensor in the FLC layer. It is found that the optical data can best be explained by a uniaxial slab twisted from the alignment axis; this is consistent with the recently proposed chevron structure.     

一种低支化聚酯液晶的合成及性能表征

采用不同比例的4,4′-对苯二甲酰二羟苯甲酸乙二醇酯（TOBB）与偏苯三酸酐（TMA）反应,合成端基含有羧基的哑铃型聚酯液晶和低支化度的聚酯液晶。通过红外光谱（FT-IR）、差示扫描量热（DSC）、偏光显微镜（POM）、广角X射线衍射（WAXD）及热重分析（TGA）等对其结构及性能进行表征。结果表明,所合成的聚酯液晶呈...     

Design of an Optical Absorption Cavity for Titanium Transition Edge Sensors

We have developed a TES optical photon detector with a titanium superconducting film showing a very fast response with rise time and fall times of 30 ns and 313 ns, respectively. The fast response is promising for many quantum measurement applications. Increasing the quantum efficiency of this device from the current value of ∼20% makes the detector even more suitable for these applications. Here we report on simulation and experimental results of a cavity designed to improve optical photon absorption of titanium.     

Uniaxial compression of a circular elastic slice

We show that some asymptotic results can be derived for the deformation of a thin circular slice of an isotropic elastic material. These results are very accurate when compared to a more exact Boundary element analysis and can be used in correlating experimental data.