Effect of surface roughness on measurement of light distribution in intralipid suspension

Light distribution in the biological tissue phantom intralipid suspension with different interface roughness was measured for quantitative understanding of surface roughness effect. The results show that the surface roughness strongly affects light distribution inside the approximately semi-infinite biological tissue phantom. The phantom surface possesses a certain degree roughness and the effect of the surface roughness on measurement results of light distribution in tissue is substantial, so the measurement of light distribution in biological tissue needs to take surface roughness into account.     

Determination of optical coefficients of biological tissue from a single integrating-sphere

The detection of interactions between light and tissue can be used to characterize the optical properties of the tissue. The development is described of a method that determines optical coefficients of biological tissue from a single optical reflectance spectrum measured with an integrating-sphere. The experimental system incorporated a DH-2000 deuterium tungsten halogen light source, a USB4000-VIS-NIR miniature fiber optic spectrometer and an integrating-sphere. Fat emulsion and ink were used to mimic the scattering and absorbing properties of tissue in the tested sample. The measured optical reflectance spectrums with different scattering and absorbing properties were used to train a back-propagation neural network (BPNN). Then the neural network (BPNN) was used to determine the optical coefficients of biological tissue from a single optical reflectance spectrum measured with an integrating-sphere. Tests on tissue-simulation phantoms showed the relative errors of this technique to be 7% for the reduced scattering coefficient and 15% for the absorption coefficients. The optical properties of human skin were also measured in vivo.     

Optical protocol for quantum state sharing of superposed coherent state

We propose an optical protocol for quantum state sharing of superposed coherent state in terms optical elements. Our protocol can realize a near-complete quantum state sharing of a superposed coherent state with arbitrary coeficients. The realization of this protocol is appealing due to the fact that the quantum state of light is robust against the decoherence and photons are ideal carriers for transmitting quantum information over long distances. This protocol can also be generalized to the multiparty system.     

短纤维增强复合泡沫弹性性能数值模拟

采用二元模型对短纤维增强复合泡沫(SFRSF)材料进行了简化模拟,考虑了纤维在空间中分布的随机性,并分别采用不同单元类型在不考虑网格匹配的情况下对纤维和基体单独进行网格划分。之后,采用改进的单元嵌入技术(EET)耦合纤维与基体的自由度,并引入杆单元模拟界面相,描述了材料内部纤维与基体的传载机制,从而建立了能反映材料细观结构的有限元数值模型。在此基础上,研究了碳纤维含量和长度以及空心微珠含量和壁厚对SFRSF杨氏模量的影响规律。结果表明,该数值模型对SFRSF杨氏模量的预测与实验值吻合较好。增加碳纤维的含量和纤维长度能够有效提高SFRSF材料的杨氏模量,适当增加空心微珠壁厚一定程度上可以增加其杨氏模量。     

磁控溅射SiC薄膜及其光电特性研究

用射频磁控溅射法制备了SiC薄膜,并对其进行了退火处理.用AFM观察了薄膜的表面形貌,测量了薄膜的厚度与透射光谱.用J.C.Manifacier提出并由R.Swanepoel加以修正和完善的包络线法对薄膜透射光谱进行了分析计算,并结合Tuac公式确定了薄膜的光学带隙.结果表明:在不同射频功率下制备的薄膜均有较强的蓝紫光吸收特性,在低功率下可制备出表面平整,吸收系数小,光学带隙大的薄膜;退火处理后薄膜的吸收系数减小,光学带隙增大,晶粒向圆形转化且尺寸变大.     

Laser methods and facilities for monitoring the geometric dimensions of components

Comparative characteristics are provided for laser methods of measuring geometric dimensions of components. The main problems are considered that arise with measurement by the triangulation method. An instrument is described that makes it possible to measure the parameters of railway wagon spring suspenders. __________ Translated from Izmeritel’naya Tekhnika, No. 2. pp. 32–35, February, 2008.     

Numerical simulation of a novel all-optical flip-flop based on a chirped nonlinear distributed feedback semiconductor laser structure using GPGPU computing

A novel all-optical flip-flop based on a chirped nonlinear distributed feedback laser structure is proposed. The flip-flop does not require a holding beam. The optical gain is provided by a current injection into an active layer. The nonlinear wave-guiding layer consists of a chirped phase shifted grating accompanied with a negative nonlinear refractive index coefficient that increases in magnitude along the wave-guide. In the ‘OFF’ state, the chirped grating does not provide the required optical feedback to start lasing. An optical pulse switches the device ‘ON’ by reducing the chirp due to the negative nonlinear refractive index coefficient. The reduced chirp grating provides enough feedback to sustain a laser mode. The device is switched ‘OFF’ by cross gain modulation. GPGPU computing allows for long simulation time of multiple SET–RESET operations. The ‘ON/OFF’ transitions delays are in nanoseconds time scale.     

Fast reconstruction of optical properties for complex segmentations in near infrared imaging

The intrinsic ill-posed nature of the inverse problem in near infrared imaging makes the reconstruction of fine details of objects deeply embedded in turbid media challenging even for the large amounts of data provided by time-resolved cameras. In addition, most reconstruction algorithms for this type of measurements are only suitable for highly symmetric geometries and rely on a linear approximation to the diffusion equation since a numerical solution of the fully non-linear problem is computationally too expensive. In this paper, we will show that a problem of practical interest can be successfully addressed making efficient use of the totality of the information supplied by time-resolved cameras. We set aside the goal of achieving high spatial resolution for deep structures and focus on the reconstruction of complex arrangements of large regions. We show numerical results based on a combined approach of wavelength-normalized data and prior geometrical information, defining a fully parallelizable problem in arbitrary geometries for time-resolved measurements. Fast reconstructions are obtained using a diffusion approximation and Monte-Carlo simulations, parallelized in a multicore computer and a GPU respectively.     

导波光学技术在测量“夹心”光学薄膜各向异性方面的应用:不同膜堆结构中同类薄膜特性的比较

本文介绍了应用导波光学技术测量“夹心”光学薄膜的特征参数的方法,并研究了比较简单的结构(由二、三层膜组成),检测到了高折射率薄膜的各向异性。从不同结构的膜系中的同类薄膜的比较中发现了单层膜与膜堆中对应的“夹心”膜之间在折射率和各向异性上的差别。     

表面粗糙度国际比对自动测量系统关键技术研究

基于中国计量科学研究院的表面粗糙度基准计量装置,开展了视觉定位系统、自动操作系统和多自由度位移系统的研究,从而实现依据国际比对协议规定流程的自动化测量。实验验证表明：该系统可有效实现表面粗糙度的自动化测量,满足国际比对的要求。在对国际比对规定的表面粗糙度标准器的测量实验中,该系统的自动定位测量的重复性为4.2 nm,相比于手动定位测量提高了2.6倍,有效地减少了测量过程中引入的人为误差。     

粗糙度对微流道内流体连续自搬运的影响

微流控芯片中各功能单元间样品的运输依赖于流体在微通道中的流动,尺度效应加剧表面作用效果,使得微流道内流体无需外部动力即可实现连续铺展搬运。为了深入研究微流道内流体的流动机制和动力学特性,分析影响微流道内流体自搬运效率的因素,基于近似Derjaguin法的同时充分考虑表面能和Casimir效应,利用数值计算和实验相结合的方法分析了微流道内壁粗糙度对流体流动特性和自搬运效率的影响,明确了微流道内流体的本构方程和流动控制方程,并设计搭建实验台验证所得结果的有效性和可靠性。结果表明：内壁粗糙度是影响微流道内流体流动特性和连续自搬运效率的重要因素;当粗糙度等效齿数、等效齿高和等效齿倾角变化时,微流道内近壁面齿隙间的主漩涡和伴生涡都相应改变,导致流体自搬运效率发生相应变化。研究结果对解决微流控润滑和微流控芯片减阻防粘等设计和使用问题具有重要理论指导意义,对微电子机械系统的小型化和集成化设计具有一定的参考价值。     

Ab-initio and DFT methodologies for computing hyperpolarizabilities and susceptibilities of highly conjugated organic compounds for nonlinear optical applications

In this talk, after a short introduction on the methodologies used for computing dipole polarizability (α), second and third-order hyperpolarizability and susceptibility; the results of theoretical studies performed on density functional theory (DFT) and ab-initio quantum mechanical calculations of nonlinear optical (NLO) properties for a few selected organic compounds and polymers will be explained. The electric dipole moments (μ) and dispersion-free first hyperpolarizabilities (β) for a family of azo-azulenes and a styrylquinolinium dye have been determined by DFT at B3LYP level. To reveal the frequency-dependent NLO behavior, the dynamic α, second hyperpolarizabilities (γ), second (χ⁽²⁾) and third-order (χ⁽³⁾) susceptibilites have been evaluated using time-dependent HartreeFock (TDHF) procedure. To provide an insight into the third-order NLO phenomena of a series of pyrrolo-tetrathiafulvalene-based molecules and pushpull azobenzene polymers, two-photon absorption (TPA) characterizations have been also investigated by means of TDHF. All computed results of the examined compounds are compared with their previous experimental findings and the measured data for similar structures in the literature. The one-photon absorption (OPA) characterizations of the title molecules have been theoretically obtained by configuration interaction (CI) method. The highest occupied molecular orbitals (HOMO), the lowest unoccupied molecular orbitals (LUMO) and the HOMO–LUMO band gaps have been revealed by DFT at B3LYP level for azo-azulenes, styrylquinolinium dye, push–pull azobenzene polymers and by parametrization method 6 (PM6) for pyrrolo-tetrathiafulvalene-based molecules.     

Features of the attenuation and single-sided imaging potential of near-infrared laser radiation in tissue-like liquid turbid media

Tissue-like phantoms are important tools in studying light propagation and scattering in biological tissues and in the development, testing and calibration of novel optical diagnostic and therapeutic methods and instruments. This motivates the interest in characterizing the optical properties of tissue-simulating turbid media. In the present work, using an original approach, the specific features have been revealed experimentally and interpreted physically (as owing to the polydispersity of the ensemble of scatterers) of the generally non-linear behaviour of the extinction (total attenuation) coefficient of Intralipid-20% dilutions in distilled water, depending on the Intralipid concentration, for near-infrared laser radiation of different wavelengths. At relatively low incremental concentrations, the values obtained of the extinction coefficient are shown to increase linearly being in agreement at each wavelength of concern with results for the integral scattering coefficient predicted by empiric formulae found by other authors. Comparative estimation has been performed as well, depending on the radiation wavelength, of the potentialities of single-sided optical sensing of tissue-like media. The estimates obtained outline the advantage of the wavelengths around the upper limit of the tissue optical window.     

Holographic digital Fourier microscopy for selective imaging of biological tissue

We present an application of digital Fourier holography for selective imaging of scatterers with different sizes in turbid media such as biological tissues. A combination of Fourier holography and high‐resolution digital recording, digital Fourier microscopy (DFM) permits crucial flexibility in applying filtering to highlight scatterers of interest in the tissue. The high‐resolution digital hologram is a result of the collation of Fourier holographic frames to form a large‐size composite hologram. It is expected that DFM has an improved signal‐to‐noise ratio as compared to conventional direct digital imaging, e.g., phase microscopy, as applied to imaging of small‐size objects. The demonstration of the Fourier filtering capacity of DFM using a biological phantom represents the main focus of this article. © 2005 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 14, 253–258, 2004; Published online inWiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.20031     

FRP加固结构界面损伤的声光纤检测数值模拟及实验

为了确保纤维复合材料(FRP)加固结构的可靠性和安全性,界面损伤检测是加固质量检查中的一个重要环节.基于薄板自由振动理论,提出一种声-光纤无损检测(NDE)FRP加固结构界面损伤的原理和方法,利用可变频的扬声器产生集中声束作用在FRP加固构件表面形成表面局部振动场,界面损伤引起的局部异常振动区的振动情况可以由粘贴在FRP表面的光纤测得,从而确定损伤的位置和大小.数值模拟分析和实验结果都表明了此方法用于FRP加固结构界面损伤检测的可行性.     

Magnetorheological nanofinishing of BK7 glass for lens manufacturing

BK7 is a high-quality crown glass which is used where additional benefits such as temperature sensitive applications of fused silica glass are not required. Due to very low inclusion content with extremely low bubbles, BK7 glass can find its application in lens manufacturing. The present work focuses on nanofinishing of the BK7 glass specimen for ratifying its utility in practical application. A programmable logic controlled 3-axis motions are fed to the magnetorheological (MR) rotating tool for finishing the glass specimen. MR polishing fluid used for nanofinishing consists of deionized water, magnetic iron particles, and cerium oxide powder. Under the influence of magnetic field, the stiffened MR polishing fluid is assisted in reducing the surface roughness of glass up to nanolevel range. Optical properties such as transmittance, absorbance, and reflectance of finished BK7 glass are analyzed and found suitable for lens manufacturing. Results of higher surface quality with excellent finishing are obtained by the present MR finishing process. After 90?min of finishing, the surface roughness values R_a and R_q are reduced to 17 and 27?nm from the initial values of 41 and 57?nm, respectively. To study the surface morphology, scanning electron microscopy is performed on BK7 glass.     

Synthesis, nonlinear optical properties and photoluminescence of ZnSe quantum dots in stable solutions

ZnSe quantum dots (QDs) were synthesized by using a novel oleic acid-controlled hydrothermal route. The as-synthesized QDs were easily dispersed in nonpolar solvents to form highly stable homogenous solutions, on the basis of which their optical properties were systematically investigated. It was found that the QDs had multiple optical properties of both obvious optical nonlinearity with a frequency-doubled Nd:YAG laser (532 nm) used as inducing beam and a strong photoluminescence emission at ca. 458 nm, suggesting that they have potential applications in complex functional optical devices.     

震荡热管应用于玻璃化保存中的数值模拟

介绍了震荡热管应用于玻璃化保存的新方案,建立了生物组织在玻璃化保存过程中的数学模型,通过ANSYS分析软件,对样品在降温过程中的温度场进行了计算分析和数值模拟.得出了生物组织的瞬时温度分布,并通过模拟结果,计算出了生物组织在降温过程中的降温速率可达2×10~4 ℃/s.研究结果表明:极快速的降温速率可使细胞或组织快速通过0 ℃--60 ℃的危险温度区域,从而抑制冰晶的生成和长大, 减轻胞内冰造成的细胞损伤.     

结构光照明层析多样性表面形貌测量

围绕散射表面和复杂微结构表面形貌高精度测量需求,对基于结构光照明的表面形貌测量技术与系统进行了研究,设计了基于科勒照明结合数字微镜器件调制的具有良好结构光对比度和均匀性的结构光照明光学系统,提出了基于高斯曲线插值的虚拟狭缝SlitMask结构照明共焦层析算法与基于迭代高斯拟合的峰值提取重建算法,建立了结构光照明表面形貌测量系统,利用单刻线对系统进行准确性与重复性测试,结果表明相对示值误差为1.87%,重复测量结果的标准差为0.0014μm。对玻璃多刻线样板和车削表面进行测试,验证了本系统不仅可用于反射表面的测量,还对散射表面具有较好的测量能力。     

A low‐cost and reliable optical inspection system for rapid surface roughness measurements of polycrystalline thin films

Excimer laser crystallization is a well‐known industrially used technique to produce high‐performance polycrystalline silicon thin films on the commercially available inexpensive glass substrates for the development of high‐performance low temperature polycrystalline silicon thin‐film transistors in active matrix flat panel displays. A rapid optical measurement system for rapid surface roughness measurement of polycrystalline silicon thin films was developed in this study. Two kinds of thicknesses of polycrystalline silicon thin films were used to study rapid surface roughness measurements. Six different incident angles were employed for measuring surface roughness of polycrystalline silicon thin films. The results reveal that the incident angle of 20° was found to be a good candidate for measuring surface roughness of polycrystalline silicon thin films. Surface roughness (y) of polycrystalline silicon thin films can be determined rapidly from the average value of reflected direct current voltage (x) measured by the optical system developed using the trend equation of y = –8.9854x + 91.496. The maximum measurement error rate of the optical measurement system developed was less than 5.72%. The savings in measurement time was up to 83%.