Electro-optical characterization of Ge–Se–Te glasses

Chalcogenide bulk glasses Ge₂₀Se_80−xTe_x for x(0,15) have been prepared by systematic replacement of Se by Te. Selected glasses have been doped with Ho, Er and Pr, and samples have been characterized by transmission spectroscopy, measurements of dc electrical conductivity and low-temperature photoluminescence. Absorption coefficients have been derived from measured transmittance and estimated reflectance. Arrhenius plots of dc electrical conductivity, in the measured temperature range 300–460 K, are characterized by single activation energies roughly equal to the half of the optical gap. Activation energies deduced from Arrhenius plots reveal a systematic decrease with increasing Te content. Similarly, both absorption and low-temperature photoluminescence spectra reveal shifts of absorption edge and/or dominant luminescence band to longer wavelength due to Te → Se substitution. Samples doped with Ho and Er exhibit a strong luminescence at 1200 and 1540 nm due to ⁵I₆ → ⁵I₈ and ⁴I_13/2 → ⁴I_15/2 transitions of Ho³⁺ and Er³⁺ ions, respectively. Pr doped samples exhibit only a relatively weak luminescence peak at 1590 nm, which we tentatively assign to ³F₃ → ³H₄ transition of Pr³⁺ ions. Absorption of the base glass luminescence at 1460 and 1520 nm has been observed at low temperature on samples doped with Pr and Er, respectively.     

Te-rich Ge–Te–Se glass for the CO2 infrared detection at 15 μm

Te_80−xGe₂₀Se_x glasses have been prepared along the GeSe₄–GeTe₄ axis using the classical method in silica tube under vacuum. A phase separation domain appears for composition around Te₄₀Ge₂₀Se₄₀. Our attention was turned toward the Te-rich compositions corresponding to 1 < x < 5 at.%. These glasses are transparent from 4 to about 20 μm without any purification of the starting elements. Furthermore the difference ΔT between the crystallization temperature T_x and the vitreous transition temperature T_g lies at about 110 °C that is to say 30 °C higher than for the GeTe₄ reference glass. Finally the introduction of a few percentages of Se makes the glasses much easier to prepare and more stable against crystallization, making them drawable as optical fibers for example. Taking into account their transparency window, encompassing the CO₂ absorption band around 15 μm, the Te_80−xGe₂₀Se_x with 1 < x < 5 at.% could become matchless composition for the CO₂ infrared detection as planed by the Darwin mission of the European Space Agency.     

Filter-radiometer-based realization of candela and establishment of photometric scale at UME

The luminous intensity unit of candela was realized based on filter-radiometer, which is traceable to detector-based primary standard electrical substitution cryogenic radiometer (ESCR). In that realization the traditional Osram Wi41/G-type incandescent lamp and filter-radiometer consisting of an aperture, a V(λ) filter and a silicon photodiode based trap detector were used as light source and detection element, respectively. Measurement techniques of effective aperture area, spectral transmittance of V(λ) filter and absolute responsivity of trap detector are also presented.     

柱前衍生化-HPLC测定仲丁胺对映体的纯度

用3, 5-二硝基苯甲酸对仲丁胺进行柱前衍生, 将其衍生物在CHIRALCEL OD-H手性固定相上拆分, 并通过二极管阵列紫外检测器对其衍生物进行检测, 建立了一种拆分仲丁胺消旋体、测定仲丁胺光学纯度的新方法. 以正己烷和乙醇或异丙醇为流动相, 在CHIRALCEL OD-H手性固定相上对仲丁胺衍生物进行了拆分, 并考察了流动相组成和柱温对该对映体衍生物分离的影响, 获得较好的分析条件, 分离因子大于1.2. 非手性试剂柱前衍生化法测定仲丁胺光学纯度与旋光度方法比较, 结果一致. 方法可用于仲丁胺对映体的质量控制.     

电压敏感染料di-4-ANEPPS的光谱研究

实验研究了电压敏感染料di-4-ANEPPS在家兔心肌组织中的吸收光谱和荧光光谱特性。结果表明,含染料组织的光吸收普遍大于对照组,在450～550 nm波段吸收谱差异更明显;染料在心室组织中的最大吸收峰为(479.75±0.44) nm。通过测量含染料心脏不同部位的荧光光谱,首次发现心室组织、心房组织和主动脉的最大荧光峰位有一定差异,其相对荧光强度则与染料的分布浓度有关。根据三维和二维荧光光谱分别确定了含染料心房和心室组织的最佳荧光激发波长和荧光测定波长。利用心房和心室组织的静息电位差,在不同波长激发光下测量了染料的荧光光谱移动,确定了光标测量实验的最佳激发光和相应荧光检测波长范围。这些研究结果为心脏光学标测系统的设计提供了理论依据。     

Algorithms for flattened Gaussian beams passing through apertured and unapertured paraxial ABCD optical systems

The propagation property of flattened Gaussian beams (FGBs) is studied based on the Collins formula, and analytical propagation equations for FGBs with and without an aperture are derived. It is shown that the closed-form expressions for the FGB of order N passing through paraxial ABCD optical systems without an aperture can be written as the combinations of Confluent Hyper-geometric Functions, and that the analytical equations for the FGB of order N passing through apertured paraxial ABCD optical systems may involve Error Functions. The proposed algorithms for the considered beams can save computing time, provide intuitive physical insights, and help to design optical systems. Our results are confirmed and illustrated with numerical examples.     

PBT／PET共混体系的协同效应

ＰＢＴ、ＰＥＴ具有良好相容性，且两种聚合物分子链间存在相互作用，它们的共混体系在熔体降温结晶过程中以及溶液中均表现出协同效应。虽然ＰＢＴ、ＰＥＴ在共混体系中各自形成晶区，但熔体降温结果过程中只能观察到一个结晶放热峰，当ＰＢＴ／ＰＥＴ共混物中两组份分子链段数目相近时，熔体降温结晶峰温较低，峰形变宽，共混体系的结晶程度降低在溶液中两组份分子链段数目相近时，共混物特性粘度（η）值最大，分子链的均方根末端     

Measurement of diameter of metal cylinders using a sinusoidally vibrating interference pattern

A method for measuring external diameters of metal cylinders is proposed in which a sinusoidally vibrating interference pattern (SVIP) of 100-μm period is used as an exact scale. Lights from the end-points of a metal cylinder are extracted with a spatial filtering in an imaging system to form a cross-sectional image of the metal cylinder. On the image a sinusoidally phase-modulated signal owing to the SVIP is detected with a CCD image sensor to measure the phases of the SVIP at the two end-points of the cylinder. The coordinates of the two end-points are obtained from the phases at the two end-points, the phase distribution of the SVIP, and the coordinates of the pixels of the CCD image sensor. Metal cylinder diameters of 7.99, 8.00, and 9.00 mm are measured along their length directions with an error less than 1 μm.     

Coupled mode analysis of in-plane channel drop filters with resonant mirrors

A channel drop filter system that consists of two waveguides and three cavities is studied. One cavity couples with both waveguides, while the other two work as resonant mirrors to reflect the selected channel back into the system. The operation of this configuration is analyzed, using coupled mode theory. The conditions to achieve 100% in-plane channel transfer are derived. A method to suppress the side lobes of reflection and backward drop is also proposed. The direct coupling between the cavities is not required. The analysis is verified by two-dimensional finite difference time domain simulations in 2D hexagonal photonic crystals.     

含有双层谐衍射元件的红外双波段光学系统消热差设计

用投影无热差图和双层衍射元件选玻璃的原则,选择了适用红外双波段消热差、消色差的玻璃组合.为提高衍射效率,基于双层衍射元件衍射效率表达式研究了双层谐衍射元件的结构优化,给出了优化方法.利用双层谐衍射元件设计的折衍混合双波段光学系统视场角10°,F#为2,有效焦距115 mm.系统在3.4~4.2 μm和8~11 μm两个工作波段的衍射效率均达到90%以上;－40~100℃温度范围内,中心视场的调制传递函数值变化最大为0.09、边缘视场的调制传递函数值变化最大为0.13.