The adsorption of protein molecules at a crystal/solution interface observed by an improved TIRFM

We have improved the ordinary total internal reflection fluorescence microscopy (TIRFM). Two improvements have been achieved, one is the interface between opaque material and solution can be observed, another is the interface far away (usually several ten micro meters) the objective lens can be observed. By this improved TIRFM, the adsorption of protein molecules at a crystal/solution interface had been successfully observed. We have obtained the results of relationship between the amount of adsorbed protein molecules on bunched steps and the height of bunched steps of a protein crystal.

The intensity distributions of collected signals in coherent anti-Stokes Raman scattering microscopy

Coherent anti-Stokes Raman scattering (CARS) microscopy with the combining of confocal and CARS techniques is a remarkable alternative for imaging chemical or biological specimens that neither fluoresce nor tolerate labeling. The CARS is a nonlinear optical process, the imaging properties of CARS microscopy will be very different from the conventional confocal microscopy. In this paper, we calculated the propagation of CARS signals by using the wave equation in medium and the slowly varying envelope approximation (SVEA), and find that the intensity angular distributions vary considerably with the different experimental configurations and the different specimen shapes. So the conventional description of microscopy (e.g.. the point spread function) will fail to descript the imaging properties of CARS microscopy. (c) 2004 Elsevier B.V. All rights reserved.

Optical gain at 1550 nm from colloidal solution of Er3+-Yb3+ codoped NaYF4 nanocubes

We demonstrated optical amplification at 1550 nm with a carbon tetrachloride solution of Er3+-Yb3+ codoped NaYF4 nanocubes synthesized with solvo-thermal route. Upon excitation with a 980 nm laser diode, the nanocube solution exhibited strong near-infrared emission by the I-4(13/2) -> I-4(15/2) transition of Er3+ ions due to energy transfer from Yb3+ ions. We obtained the highest optical gain coefficient at 1550 nm of 0.58 cm(-1) for the solution with the pumping power of 200 mW. This colloidal solution might be a promising candidate as a liquid medium for optical amplifier and laser at the optical communication wavelength. (C) 2009 Optical Society of America

Imaging and tracking single fluorescent nanobeads in solution

In single-particle tracking (SPT), fluorescence video microscopy is used to record the motion images of single particle or single molecule. Here, by using a total-internal-reflection microscope equipped with an argon ion laser and a charge-coupled device (CCD) camera with high-speed and high-sensitivity, video images of single nanobeads in solutions were obtained. From the trajectories, the diffusion coefficient of individual nanobead was determined by the mean square displacements as a function of time. The sizes of nanobeads were calculated by Stokes-Einstein equation, and the results were compared with the actual values.

Instability of solution of phase retrieval in direct diffraction phase-contrast imaging with partially coherent X-ray source

The theoretical model of direct diffraction phase-contrast imaging with partially coherent x-ray source is expressed by an operator of multiple integral. It is presented that the integral operator is linear. The problem of its phase retrieval is described by solving an operator equation of multiple integral. It is demonstrated that the solution of the phase retrieval is unstable. The numerical simulation is performed and the result validates that the solution of the phase retrieval is unstable.

Vectorial solution of Kukhtarev equations for doubly doped crystals and optimal choice of recording directions in nonvolatile holographic storage

Vectorial Kukhtarev equations modified for the nonvolatile holographic recording in doubly doped crystals are analyzed, in which the bulk photovoltaic effect and the external electrical field are both considered. On the basis of small modulation approximation, both the analytic solution to the space-charge field with time in the recording phase and in the readout phase are deduced. The analytic solutions can be easily simplified to adapt the one-center model, and they have the same analytic expressions given those when the grating vector is along the optical axis. Based on the vectorial analyses of the band transport model an optimal recording direction is given to maximize the refractive index change in doubly doped LiNbO3:Fe: Mn crystals. (c) 2007 Optical Society of America.

窄带和宽带双曲正割脉冲光束的解析传输式

从近轴波动方程出发推导了窄带和宽带双曲正割脉冲光束的解析传输公式。通过数值计算比较了分别采用复振幅包络(CAE)表示式和复解析信号(CAS)表示式得到的脉冲光束，得出了选择脉冲光束研究方法的条件。结果表明复振幅包络表示式得到的解会存在空间奇异性，使光束出现不符合物理意义的非光束行为。对于宽带光束，复振幅包络解的奇异点的位置距离轴中心较近，使复包络解不能正确表示脉冲光束，而对于奇异点位置远离轴中心的窄带光束，对脉冲光束产生的影响可以忽略。因此，窄带脉冲光束可以采用复振幅包络和复解析信号两种表示式来研究，而对

Encoded cell grating array in anti-counterfeit technology

The dot matrix hologram (DMH) has been widely used in anti-counterfeiting label. With the same technology and cell array configuration, we can encode to the incidence beam. These codes can be some image matrix grating with different grating gap and different grating orientation. When the multi-level phase diffractive grating is etched, the incidence beam on the cell appears as an encoding image. When the encoded grating and DMH are used in the same label synchronously, the technology of multi-encoded grating array enhances the anti-counterfeit ability.

Solution combustion synthesis, structure and luminescence of Y3Al5O12 : Tb3+ phosphors

The synthesis and optical properties of Y3Al5O12:Tb3+ phosphors are reported in this paper. Y3Al5O12:Tb3+ phosphors were synthesized by a facile solution combustion method. Citric acid traps the constituent cations and also acts as a fuel. Y3Al5O12 (YAG) phase can crystallize through sintering at 900 degrees C for 2 h, and there were no intermediate phases such as YAlO3 (YAP) and Y4Al2O9 (YAM) in the sintering process. The excitation spectra of crystalline Y3Al5O12:Tb3+ are different from that of amorphous one due to the crystal field effect. The emission spectra mainly show D-5(4) -> F-7(6) transition under UV excitation. The higher concentration quenching in Y3Al5O12:Tb3+ nanophosphors may be due to the confinement effect on resonant energy transfer of nanocrystalline. It is also indicated that the solution combustion synthesis method provides a good distribution of Tb3+ activators in Y3Al5O12 host. (c) 2005 Published by Elsevier B.V.

Eu:Y2O3 nano-phosphor prepared by novel energy-saving solution combustion method

A novel energy- and time-saving solution combustion method has been developed to prepare Eu:Y2O3 nano-crystal line phosphor. This novel method employs anhydrous ethanol as solvent and fuel. The prepared nano-crystals after heat-treatment own narrow size distribution, well dispersibility and sinterability, confirmed by XRD, TEM and FTIR. The emission spectra of nano-Eu:Y2O3 Samples show clear nano-size related phenomena. (c) 2007 Elsevier B.V. All rights reserved.

Synthesis and luminescence characterization of cerium doped Lu2O3-Y2O3-La2O3 solid solution transparent ceramics

Ce3+:( Lu0.7Y0.25La0.05)(2)O-3 transparent ceramics were fabricated with nanopowders and sintered in H-2 atmosphere. The spectral properties of Ce3+:( Lu0.7Y0.25La0.05)(2)O-3 transparent ceramics were investigated and the luminescence of Ce3+ in the solid solution of Lu2O3, Y2O3 and La2O3 has been found. The ceramics has high density of 8.10g/cm(3) and short fluorescence lifetimes of 7.15 ns and 26.92 ns. It is expected to be a good fast response high temperature inorganic scintillating materials. (C) 2008 Optical Society of America.

Influence of vacuum organic contaminations on laser-induced damage of 1064 nm anti-reflective coatings

We investigate the influence of vacuum organic contaminations on laser-induced damage threshold (LIDT) of optical coatings. Anti-reflective (AR) coatings at 1064 nm made by Ta2O5/SiO2 are deposited by the ion beam sputtering method. The LIDTs of AR coatings are measured in vacuum and in atmosphere, respectively. It is exhibited that contaminations in vacuum are easily to be absorbed onto optical surface because of lower pressure, and they become origins of damage, resulting in the decrease of LIDT from 24.5 J/cm(2) in air to 15.7 J/cm(2) in vacuum. The LIDT of coatings in vacuum has is slightly changed compared with the value in atmosphere after the organic contaminations are wiped off. These results indicate that organic contaminations are the main reason of the LIDT decrease in vacuum. Additionally, damage morphologies have distinct changes from vacuum to atmosphere because of the differences between the residual stress and thermal decomposability of filmy materials.