Application of a NDI method using magneto-optical film for micro-cracks

Leakage magnetic flux is occurred in the cracked area of magnetized specimens, and also it changes the magnetic domain area of the magneto-optical film positioned on the specimen. It causes the change of the optical permeability of the magnetic domain on the crack area. So crack images can be obtained easily using this principle. On the other hand, utilizing a laser in this method makes possible to perform a remote sensing by detecting the light intensity contrast between cracked area and normal area. This paper shows the application of non-destructive inspection system taking advantage of magneto-optical method for micro-cracks and presents examples applied to the several types of specimens having fatigue cracks and fabricated cracks using this method. Also the authors prove the possibility of this method as a remote sensing system under the oscillation load considering application to real fields.     

Note: epitaxial ruby thin film based photonic sensor for temperature measurement

Deposition of optical quality C-axis oriented epitaxial thin film of ruby via pulsed laser deposition technique on sapphire substrate is reported. The film is characterized by Raman spectra and photoluminescence spectra. The peak positions of R-line and the corresponding linewidth are observed to be temperature dependent. The sensitivity of R(1)-line position, υ, with the temperature, (dυ/dT), in the range of 138-368 K shows linear behavior confirming its applicability as temperature sensor.     

Correlation method for processing speckle patterns of dynamic light scattering by small particles based on spatial averaging of data

A correlation method for processing dynamic light scattering patterns resulting from laser radiation propagation through solutions and suspensions is proposed which is based on spatial averaging of measurement data on the correlation functions of the intensity of light scattered by small particles.     

碘化物-十六烷基三甲基溴化铵体系共振光散射法测定铜

用简易荧光计研究了在微酸性介质中铜-碘化钾-十六烷基三甲基溴化铵(CTAB)体系的共振散射光谱,考查了它的光谱特征,影响因素和适宜的反应条件。实验发现,在Cu(I)存在条件下,I--CTAB溶液的共振光散射强度会大大增加。根据散射光强度与溶液中铜浓度在一定范围内成正比的关系,提出了共振光散射法测定水样中铜方法。该法可在室温下进行操作,并具有较高的灵敏度,线性范围为0.0～0.6μgmL,方法的捡出限为0.005μgmL。用于环境水样中铜浓度的测定,结果满意。     

动态线偏振光散射纳米颗粒粒度测量法的研究与分析

多重散射是传统动态光散射法测量纳米颗粒溶液浓度上限受到限制的主要原因。为此文中提出了动态线偏振光散射纳米颗粒粒度测量法,通过改变颗粒入射光和散射光的偏振状态,降低颗粒间多重散射的影响。现利用Mie散射理论分析了入射光与散射光偏振状态之间的关系,并通过实验方法探知偏振光在散射介质中的传输特性,揭示了在动态光散射中使用垂直偏振光作为入射光的实验依据。最后对动态线偏振光散射颗粒测量法和传统光子相关光谱测量法进行了实验及分析,通过两种方法的比较,验证了上述理论的正确性。     

Note: response characteristics of the sensor based on LaF3 thin film to different humidified gases

Electromotive force (EMF) transient curves presented that the sensor showed good repeatable response in the humidity environments using ambient atmosphere as the carrier gas at different temperatures. The 90% response time and recovery time were within 40 s and 50 s, respectively. The sensor also presented stable response characteristics in 75.1% RH and 83.6% RH humidity environments using N(2), 5% O(2), and 50% O(2) as the carrier gases, respectively. The EMF always increased with the partial pressure of oxygen in certain relative humidity. However, the ΔEMF was decreased with the increase of O(2) content in the carrier gas under the condition of the variation of relative humidity from 75.1% to 83.6%. These phenomena revealed that the sensor was sensitive to water vapor without oxygen in the sample gas and too much water vapor had adverse effect on the response to oxygen. Non-Nernst behavior of the sensor was discussed in detail.     

Analysis of light scattering by rough manufactured surfaces

The relationship between the roughness of a manufactured surface and the angular distribution of the light scattered by that source is presented. A one-dimensional rough surface model is considered. It has been found that the angular distribution of the light scattered in the Fraunhofer zone is proportional to the square of the Fourier transform modulus of the surface reflection function. If the peak-to-valley height of the surface roughness is small compared with the light wavelength, the angular distribution of the light scattered is proportional to the power spectrum of the profile. If the peak-to-valley height of the surface roughness is comparable with or greater than the light wavelength, the angular distribution of the light scattered can be determined by using the suggested light scatter simulating system.     

Low-frequency Raman scattering of light by silver nanoparticles

Silver nanoparticles sprayed onto a crystalline quartz substrate are characterized by means of the low-frequency Raman scattering. Contributions of silver nanoparticles of different sizes to the Raman scattering spectrum are estimated. Data of scanning electron microscopy are used to verify the validity of the results obtained.     

适用于光照不均匀图像的边缘检测算法

首先利用图像梯度方向特征改进Canny算法,使之更适合连续边缘的检测。然后将其与基于侧抑制原理的图像增强算法结合,设计了一种新的适用于噪声背景下光照不均匀图像的边缘检测算法。算法实验结果表明该边缘检测算法能有效提取光照不均匀图像中的连续边缘。     

Note: design and characterization of an optical light source based on mixture of white and near-ultraviolet light emitting diode spectra

An optical light source based on a solid-state lighting technology is designed. Main components of the light source are a phosphor-converted white and a near-ultraviolet (near-UV) light emitting diodes (LEDs), the spectral power distributions (SPDs) of which are mixed using a fiber optic combiner. The near-UV LED is used for improving insufficient SPDs of the white LED at shorter wavelengths of the visible radiation. Stable direct current power supplies are also designed and used to operate each of the LED separately. Three steps of the driving current can be selected by means of serial resistors altered with a commutator at nominal current values of ～40%, ～50%, and ～69%. The light source can be used for many characteristic measurements within the scope of photometry and colorimetry.     

Study on residual stress in viscoelastic thin film using curvature measurement method

Using LSM (laser scanning method), the radius of curvature due to thermal deformation in polyimide film coated on Si substrate is measured. Since the polyimide film shows viscoelastic behavior, i.e., the modulus and deformation of the film vary with time and temperature, we estimate the relaxation modulus and the residual stresses of the polyimide film by measuring the radius of curvature and subsequently by performing viscoelastic analysis. The residual stresses relax by an amount of 10% at 100°C and 20% at 150°C for two hours.     

Note: analysis of the efficiency of a dielectric elastomer generator for energy harvesting

In this study, a dielectric elastomer (DE) generator is developed for micropower generation, and its efficiency is derived. It is shown explicitly that power generation efficiency depends on the thickness of the DE generator, the charging voltage, the effective stiffness of the DE generator, the dielectric constant, and the relative deformation. Through experiments with VHB? 4905 film, the proposed analysis is verified. In particular, the effective stiffness of a DE generator inversely improves the power generation efficiency.     

散射法表面粗糙度测量

介绍了标量和矢量两种散射理论,并用软X射线反射率对超光滑表面进行散射测量,同时应用这两种理论计算了超光滑表面粗度均方根值,从计算结果来看,两种理论所得结果与WYKO测量结果吻合较好。     

Characterization of high-quality surfaces by Nomarski microscopy and light scattering

Supersmooth mirror substrates for laser-gyro applications were investigated. Bare samples made of BK7 glass, fused silica, and different silicon wafers were examined. Nomarski differential interference contrast microscopy was used to characterize the quality of the surfaces using a specially selected microscope objective with ultralow internal light scatter. The microscope system resolved a root mean square roughness in the range of 0.05 nm. Photographs of these supersmooth surface structures are presented. To obtain additional information, the total integrated light scattering of the bare substrates was measured. An Ulbricht integrating sphere with a diameter of 0.125 m was used for this purpose. Unwanted light scatter by the rear side of the transparent substrate was blocked using a special diaphragm. A specially developed polishing process that yields surfaces with a roughness of about 0.1 nm and probably lower is discussed.     

应用面阵CCD的优化光点定位方法

传统的灰度重心法是一种用于对称目标的亚像素定位算法,其计算精度不高而且抗噪声性能较差.提出一种隔离算法,将其边缘像素分离,然后对内部像素灰度进行均值化,从而有效抑制内部像素噪声.同时,利用数据误差理论对这种算法的误差进行分析.最后,通过基于大天区面积多目标光纤光谱天文望远镜(LAMOST)标定实验,验证了这种算法的正确性,并表明优化算法有较好的噪声抑制性能.     

大数据多尺度状态检测方法在磨损检测的应用

随着生产过程自动化、信息化、规模化发展,以大数据为基础的信息处理技术得到广泛应用.对大数据进行多尺度深层次的挖掘,可以为状态检测提供技术依据,有效提高设备的可靠性.针对数据量巨大、干扰源众多、信息密度低、复杂度高的对象提出一种基于大数据的状态检测方法,利用数据融合、信息粒化以及多尺度分析,提取对象状态参数.通过对某机组磨煤机磨辊磨损的状态检测的实例分析验证了算法的有效性.     

Note: A signal-to-noise ratio enhancement based on wafer light irradiation system for optical modulation spectroscopy measurement

We have recently found that the magnitude of the photoreflectance (PR) signal ΔR∕R on silicon wafers depends on the duration of continuous probe or pump beams irradiation. This temporal behavior of the ΔR∕R signal is attributed to the defects related electronic states at the Si∕ SiO(2) interface, which could be modified by the optical irradiation. Prior to the actual measurement, an optical irradiation of the silicon on insulator or ion implanted Si wafer can significantly enhance the signal-to-noise ratio of the PR intensity and, therefore, improve the goodness of fit. Such phenomena can be exclusively seen using a rapid detection system. A new design of the method is reported.     

Investigation of low-angle laser light scattering patterns using the modified Twomey iterative method for particle sizing

We first applied the Twomey iteration method to the low-angle laser light scattering (LALLS) method. The Twomey method is known by the simple iteration algorithm for Fredholm integral equation. However, the algorithm is not applied to the LALLS result itself because the kernel function pattern is not stable. We solved the unstable kernel issue by modifying the Twomey algorithm to fit the LALLS data in this study. The performance of inversion was studied by computer simulation and experimental results from detectors containing 24 elements from angle 0.0005 to 2.5 rad. The computer simulation was carried out for particles of mean sizes from 0.1 to 1000 μm with mono-dispersion and log-normal distributions. A conventional algorithm is also carried out to compare the performance of the Twomey method. The noise effect of the inverse problem was tested by computer simulation. Experimental results were measured with standard polystyrene latex from 0.081 to 1007 μm. All the tests were performed under conditions in which the light from a linearly polarized laser at 633 nm was scattered by a diluted aqueous suspension. The modified Twomey (MT) method and conventional method show good reproduction results for particles with log-normal distributions. However, narrow distribution particles indicate that the MT method shows excellent reproduction results when compared with the conventional method.     

一种基于频率的结构损伤识别方法及识别矩阵的建立

本文介绍了一种比较好的损伤识别方法。这种方法要求建立损伤识别矩阵,损伤识别矩阵的建立是这个方法是否能准确识别的关键,在研究中,发现根据不同的标准建立的识别矩阵识别的效果不同;并进一步指出如何建立能够准确识别损伤的识别矩阵。