Clustering study in Eu(DBM)3Phen-doped polymer optical fibers by optical properties and near-field scanning microscopy

The clusters of Eu3+ ion in Eu(DBM)3Phen-doped polymethyl methacrylate (PMMA) have been studied by three means. The relative fluorescence intensity ratio of the 5D0 → 7F2 to 5D0 → 7F1 transitions with different concentrations of Eu3+ in Eu(DBM)3Phen-doped PMMA and metastable-state (5D0) lifetime dependence on Eu3+ concentration are analyzed. The analysis indicates that there are no clustering effects in Eu3+ ions of Eu(DBM)3Phen-doped PMMA when the Eu3+ doping concentration is up to 1.0 wt.-%. At the same time, the clustering effect has not been observed by the scanning near-field optical microscopy (SNOM) in Eu(DBM)3Phen-doped PMMA with 1.0 wt.-% of Eu3+ ions. The analysis reveals that a high concentration of Eu3+ can be incorporated into polymer optical fiber (POF) without clustering effect.OCIS codes: 180.5810, 300.6280, 250.5460, 160.5690.     

Holographic optical elements (HOE) for semiconductor lasers

A two step method is described to produce off-axis holographic lenses with high diffraction efficiency and without astigmatism for semiconductor lasers. The hologram is recorded in the visible (514 nm) and reconstructed in the infrared (800 nm). The principal parameters (recording and reconstruction angles, astigmatic focal lengths) for each hologram and wavelength are calculated analytically using second order approximation. Numerical methods, based on classical ray-tracing applied to holographic diffraction, have been developed to calculate spot diagrams and to investigate the effects of higher order aberrations.     

A resonance tracking method for stable operation of a near-field scanning optical microscope in liquid environment

We report on the novel design of the near-field scanning optical microscope (NSOM) which operates in liquid environment. A resonance tracking digital scanning method is applied to compensate the resonance shift due to the evaporation of the liquid in the atmospheric pressure. By this method, stable operation of NSOM system is demonstrated by showing topographic images of the metallic grating embedded in liquid environment.     

Imaging of human meiotic chromosomes by scanning near-field optical microscopy (SNOM)

Centromeres and telomeres are key structures of mitotic and meiotic chromosomes. Especially telomeres develop particular structural properties at meiosis. Here, we investigated the feasibility of scanning near-field optical microscopy (SNOM) for light-microscopic imaging of meiotic telomeres in the sub-hundred nanometer resolution regime. SNOM was applied to visualise the synaptonemal complex (SC) and telomere proteins (TRF1, TRF2) after differential immuno-fluorescent labelling. We tested and compared two different preparation protocols for their applicability in a SNOM setting using micro-fabricated silicon nitride aperture tips. Protocol I consisted of differential labelling of meiotic chromosome cores (SC) by SCP3 immuno-fluorescence and telomeres by TRF1 or TRF2 immuno-fluorescence, while protocol II combined absorption labelling with alkaline phosphatase substrates of cores with fluorescent labelling of telomeres. The results obtained indicate that protocol I reveals a better visualisation of structural (topographic) details than protocol II. By means of SNOM, meiotic chromosome cores could be visualised at a resolution overtopping that of far-field light microscopy.     

A vibrational study of liquid benzene through dispersive Raman spectroscopy using advanced optical elements

A compact experimental setup using advanced optical elements was designed to take Raman spectrum of liquid benzene. All seven Raman active vibrational modes were observed. A simplified mechanical model for two most intense in-phase modes, i.e., ring breathing and C–H stretching, shows that the vibrational contribution to the ratio of C–C and C–H bond strengths is a factor of ～1.66. A simulation of Raman spectrum with Gaussian vibrational bands, weighted by Planck distribution function, yields the vibrational line widths and the relative polarizability changes. A value of 0.74 is estimated for the ratio of change in polarizability of C–H bond to that of C–C bond upon laser excitation from a simple electrostatic calculation, which is comparable with the value of 0.6 obtained from the simulation.     

Polarization effects in apertureless scanning near-field optical microscopy: an experimental study

Strong electric-field enhancements at the apex of a tungsten tip illuminated by an external light source were recently predicted theoretically. We present an experimental study of the dependence of this effect on the polarization angle of the incident light. It is shown that the intensity of the light scattered by the tungsten tip of an apertureless scanning near-field optical microscope is 2 orders of magnitude higher when the incident light is p polarized than when it is s polarized. This experimental result is in good agreement with theoretical predictions and provides an easy way to test the quality of the tips.     

疏水性离子液体萃取-原子吸收光谱法分离分析微量金

以N-甲基咪唑和溴代正丁烷及六氟磷酸铵合成了疏水性离子液体1-丁基-3-甲基咪唑六氟磷酸盐([Bmim][PF6])。运用该离子液体分离富集分析了微量金。以火焰原子吸收光谱法(FAAS)为分析检测手段,探讨了离子液体萃取预富集微量金的条件。实验结果表明:金的浓度在0.40～16.00μg·mL-1范围内与吸光度成线性关系,线性方程为A=0.00763c+0.07387(c:μg·mL-1),r=0.9991,检测限为0.072μg·mL-1。该法用于样品测定结果令人满意。     

A LEED study of the InP(110) surface: I. Experiment and preliminary analysis

A preliminary LEED theory experiment comparison for the InP(110) surface has been performed using experimental I(V) data recorded in the authors' laboratory from a clean, UHV-cleaved, single crystal specimen. A range of model surface geometries including both lateral and vertical displacements of the top layer In and P atoms have been examined. The results clearly demonstrate that the structure of this surface is substantially different from a simple termination of the bulk lattice and that the disturbance extends more than one layer into the real crystal. The possibility of extending the analysis to include second layer distortions is considered.     

Nanoscopic study of second-harmonic generation in organic crystals with collection-mode near-field scanning optical microscopy

Collection-mode near-field scanning optical microscopy (NSOM) is used to map nanoscopic second-harmonic generation (SHG) in N -(4-nitrophenyl)- (L) -prolinol crystals. A spatial resolution of 98 nm is achieved. Near-field polarization-dependent SHG measurement is performed, and a local effective SHG susceptibility of 224+/-18 pm/V is obtained.     

High-sensitivity piezoelectric tube sensor for shear-force detection in scanning near-field optical microscopy

An easy-to-implement non-optical shear-force detection setup for tip–sample distance regulation in scanning near-field optical microscopy is demonstrated. The detection method is based on attaching the near-field probe to a piezoelectric tube resulting in excellent mechanical contact between tip and detector. The main advantages of the method are good signal-to-background contrast and thus potential for high sensitivity. The method is demonstrated by obtaining approach curves of silicon surfaces. The suitability for optical experiments is further shown by measuring the near-field intensity distribution of the emission of a semiconductor laser.     

Field stitching algorithm for the analysis of electrically large diffractive optical elements

A rigorous electromagnetic algorithm is presented for the analysis of electrically large diffractive optical elements (DOE's), i.e., those that contain small features and have large apertures compared with the wavelength of illumination. The technique uses a finite-sized analysis window within which a rigorous electromagnetic technique is used to solve the local boundary-value problem. To this end the boundary-element and finite-difference time-domain methods are used. The analysis window is translated over the entire surface of the DOE and stitches together the complete solution. We validate the techniques by comparing the stitched boundary fields with those of a complete analysis, in both magnitude and phase, for a binary lens. To illustrate the utility of our method we analyzed an eight-level diffractive lens with a 10, 000-wavelength diameter sampled at 0.05 wavelength that required 8 Mbytes of memory on a desktop personal computer.     

一阶不连续光学元件MRF流体动力学分析方法

一阶不连续光学元件的磁流变抛光问题是制约我国高精高效光学制造领域发展的难题之一,其涉及锥形、矩形等几何形貌元件的光学元件加工问题以及常见光学元件的边缘效应控制问题。提出了基于一阶不连续光学元件的磁流变抛光流体动力学方法,建立了该类元件抛光区域流体动力分析的理论方法和数值手段。首先,对磁流变抛光工况下的流场进行了合理假设,其次,从微元流体动力方程出发,建立了适用于一阶不连续面形的流场分析方法,最后,基于有限差分法和数值迭代方法建立了流场控制方程的数值计算方法。通过对切入距离为1~18 mm的抛光过程进行数值仿真,发现该方法所获取的一阶不连续面形的压力分布形态是正确的,产生的不连续压降与实验观测一致。     

Tapping mode atomic force microscope combined with reflection scanning near-field optical microscope (AF/RSNOM)

A new kind of scanning probe microscope is introduced in this paper, which is a combination of atomic force microscope and reflection scanning near field optical microscopy (AF/RSNOM) with equi-amplitude tapping mode. The principle and recent experiment result of AF/RSNOM are reported. Besides convenient operation, the bi-functional probe tip of AF/RSNOM brings an even illumination for every sampling position. Experiment result and analysis show that the signal to noise ratio (SNR) of AF/RSNOM optical image is much better than that of other RSNOM without tapping working mode.     

基于Ansys的光学器件热变形仿真与分析

由于环境温度的作用,光学器件在应用环境中的热变形对光学仪器的整体性能产生重要影响,利用有限元分析系统对光学器件进行热变形分析,为器件设计提供科学依据和有效支持。提出基于Ansys的热变形仿真分析方法。该方法包括问题分析、Ansys热变形仿真和数据分析3个步骤,并对每一步内容作了详细阐述和说明。以某光学仪器的关键器件为分析对象,用该方法进行了热变形仿真,应用Matlab软件进行结果数据分析,得到了器件反射镜面在40℃和-10℃环境温度影响下产生的平行差分别为7.62412″和8.56317″。所得结果与实验结果基本一致,证实了该方法的有效性。     

Can the optical excitations of surface plasmons be used to study (liquid) metal surfaces?

The surface plasmon dispersion relation is obtained for a metal with a free electron density given by N(z) = N_b + (N_s ? N_b) exp $\text{(}\text{?z}\text{a}\text{)}$ for z ? 0 and N = 0 for z < 0. We have used a local theory which includes the effects of retarded fields and found the dispersion relation to be sensitive to the parameters $\text{(N}{}_{\mathrm{s}}\text{? N}{}_{\mathrm{b}}\text{)}\text{N}{}_{\mathrm{b}}$ and a, which characterize our density profile.     

Optimization and analysis of multi-layer diffractive optical elements in visible waveband

An optimization for diffraction efficiency of the multi-layer diffractive optical elements (MLDOEs) is presented, then the construction process of optimization program is introduced in detail. A new optimization initial point is proposed, which contributes to analyze the relationship between the optimal relief heights and the base materials. Through the optimization examples, diffraction efficiency higher than 99.7% from F line (486.1327 nm) to C line (656.2725 nm) of visible waveband can be achieved, and the polychromatic integral diffraction efficiency (PIDE) over the entire waveband is 99.94%. Moreover, this paper compares and analyzes optimization results of different glass pairs, and the relationship between the optimal relief heights pairs and base materials pairs is obtained.     

测量大口径光学元件反射率用精密扫描系统误差分析

为测量高能激光传输系统中大口径高反射率光学元件的反射率,设计了一种大口径光学元件二维扫描的精密测量系统。介绍了该系统的结构及其工作原理,分析了影响系统测量精度的因素,从理论上分析了扫描系统的系统误差对测量精度的影响,结果表明在垂直于光束传播方向上,水平偏差在0.29 mm时,测量误差在10-6量级;腔长的变化量较小时,可通过对衰荡腔腔镜的调节,实现对旋转轴偏差的补偿及对系统的精细调节。通过拟合处理光强与时间的数据得到对应的一次指数函数拟合曲线,并通过计算得到衰荡时间和反射率,经过对比分析可知,该误差分析方法能比较有效地测量腔镜的反射率,并能减小实验数据本身带来的误差。     

Design procedure using coupled multiwave efficiency analysis for wavelength shifted holographic optical elements

A design procedure uses coupled multiwave efficiency analysis in wavelength shifted holographic optical elements. The procedure is adapted for producing 488 nm holographic lenses for use at 628 nm.     

光学元件狭缝柔性调节机构的设计与分析

设计了一种狭缝柔性结构的光学元件调节机构,使光学元件在具备较高调节精度的同时,保持较高的导向精度。采用弹性力学应力函数法分析了狭缝柔性结构的刚度,以径向刚度与轴向刚度的比值为目标函数,对狭缝柔性结构尺寸参数进行了优化,在不超过柔性结构材料屈服应力等约束条件下,刚度比最优值达到1 573.6,较大的刚度比值可以减小调节机构的耦合位移,从而提高机构的导向精度。该结构加工装配方便,可实现三自由度(θx-θy-Z)调节。对优化后的柔性结构进行仿真分析,结果表明:径向刚度与轴向刚度比值的仿真值为1 660.4,解析值与仿真值误差为5.23%,证明了刚度分析方法的有效性。优化后的结构,轴向调节行程为2.09 mm,绕x轴偏转角度调节行程为±16.6 mrad,绕y轴偏转角度调节行程可达到±14.4 mrad,满足光学元件调节的大行程要求。