We propose a method to eliminate the noise of a disordered medium optical transmission matrix. Gaussian noise exists whenever light passes through the medium, during the measurement of the transmission matrix and thus cannot be ignored. Experiments and comparison of noise eliminating before and after are performed to illustrate the effectiveness and advance presented by our method. After noise elimination, the results of focusing and imaging are better than the effect before noise elimination, and the measurement of the transmission matrix is more consistent with the theoretical analysis as well.

针对转炉冶炼终点传统人工肉眼看火判断存在着诸多不确定性问题,研究了一种基于模糊支持向量机的光辐射状态识别实现转炉终点判断的方法。设计了非接触式炉口光辐射采集系统,基于炉口火焰辐射规律分析,分别提取了通过高斯函数拟合表征光谱整体特征的三参数和两个发射峰离散谱参数作为支持向量机的输入,通过相关性分析选出生产过程中氧量、动枪幅度、爽枪时间、加料量参数构建子样本特征量,采用样本到类间距离的方法计算隶属度因子,建立了模糊支持向量机识别模型并进行了测试实验。实验结果表明,提出的方法对不同操作工况下的终点光辐射识别精度优于人工方法和传统SVM方法,可为转炉终点的准确判断提供依据。

Nanostructures like a piece of porous film with an array of nanoholes have many interesting properties with the existence of surface plasmon resonance. In this paper we use numerical simulation method to calculate the electric field and phase properties in near and far fields of a metal nanohole array. The effect of SPP on the near-field polarization state was found in the results. We also introduced a ring array structure which has a higher normalized transmission rate and two transmission peaks. In which we observed the existence of polarization singularities and the topology of the surrounding electric field is also determined.

The scintillation index of pseudo-Bessel-Gaussian Schell-mode (PBGSM) beams propagating through atmospheric turbulence is analyzed with the help of wave optics simulation due to the analytic difficulties. It is found that in the strong fluctuation regime, the PBGSM beams are more resistant to the turbulence with the appropriate parameters beta and b. However, the case is contrary in the weak fluctuation regime. Our simulation results indicate that the PBGSM beams may be applied to free-space optical (FSO) communication systems only when the turbulence is strong or the propagation distance is long. (C) 2017 Elsevier Ltd. All rights reserved.

There are some problems in optical education such as insufficient flexibility, individuality and adaptability to students who need information and education at present. The development of mobile internet and technology provides support to solve these problems. Basic characteristics, advantages and developments of these techniques used in education are presented in this paper. Mobile internet is introduced to reform the classroom teaching of optical courses. Mobile network tool selection, teaching resources construction and reform in teaching methods are discussed. Academic record and sampling surveys are used to assess intention to adopt mobile internet and learning effect of academic major of students, the results show that high quality optical education can be offered by adopting mobile internet and technologies in traditional instruction.

In this paper, we discuss the concept of cross-spectral purity of Stokes parameters, purity of general partial polarization and implications of statistical similarity of an optical field. The conditions of cross-spectral purity of Stokes parameters and purity of partial polarization are obtained. Then, by utilizing statistical similarity, the relationships between the two purity and spatial coherence are explored. At last, a special situation that gives a relation of these two kinds of purity is briefly discussed.

The distributions of (or constraints for) amplitude and phase around C-points, including Lemon, Mon-Star and Star, are studied. A Cartesian coordinate system with origin at the C-point is established. Four curves, where the azimuthal angles of polarization ellipses are 0°, 45°, 90°, and 135° respectively, are used to determine the distributions. Discussions of these constraints illustrate why Mon-Star is rarer than Lemon or Star in experiments. The transformation relationships between these three polarization singularities (PSs) are also discussed. We construct suitable functions for amplitude and phase according to their constraints, and simulate several PSs of particular shapes. With the development of modulation techniques for amplitude and phase, it is clear that this work is helpful for generating arbitrarily shaped C-points in experiments.

Aiming at an accurate endpoint control of the basic oxygen steelmaking (BOS) with two blowing stages, a new prediction method based on the flame spectral analysis and multi-class classification is proposed for those small-sized and middle-sized converters. Based on the fact that the experienced operators mainly control the blowing process by the flame variation at the converter mouth, a converter radiation information acquisition system is adopted to analyze the end period of the blowing from the perspective of different flame spectral characteristics. Besides, different blowing processes are divided into four sub-classes corresponding to different endpoint carbon content, and support vector machine is used to construct the multi-class classifier. The proposed model is validated by real industrial dataset, and results show that the mentioned method can play a good auxiliary role in the operators’ endpoint prediction.

针对一种压电陶瓷预负载结构,利用光学干涉法测量了其位移-电压特性,在测量过程中观察到压电装置及其支撑结构本身的共振会影响测量结果的准确性.进而对不同材质的多种压电装置采用不同的驱动频率进行了对比实验,证明了基于传统的测量装置应采用多次测量以获得更严谨的压电响应参数.

在激光器的设计及使用过程中,观察到激光器安装板的结构对激光器输出功率的稳定性能够起到关键作用.在对安装板施加一定螺钉预紧力时,安装板的变形一般会导致激光器输出功率的大小出现不同程度的变化.为了减小安装板变形对激光器输出功率稳定性的影响,设计了3种安装板结构,采用有限元方法分别模拟了施加一定螺钉预紧力时的变形情况,并实验测量了几种情况下的输出功率.模拟和实验结果均表明,相比未作处理或螺孔侧面开孔的安装板结构,采用开侧槽安装板的激光器的功率受螺钉预紧力的影响较小,是一种更为稳定可靠的激光器安装板结构.

对转炉炼钢过程中炉口火焰温度的非接触式在线测量进行了研究.采用无需假设发射率模型的基于最小二乘法的多光谱测温法,利用海洋光学的微型光谱仪USB4000作为分光器件,构建了相应的炉口火焰辐射信息采集系统.采用与炉口火焰温度相近的炉内铁水作为辐射源对系统进行标定,获得其响应系数.选取不同波段的光谱数据,分别将改进的标定方式以及利用卤钨灯进行标定的方式应用于倒炉铁水温度的测量,测温结果表明,波长区间为600～740 nm时,采用改进的方式取得的结果最优.将该方法应用于冶炼过程中炉口火焰温度的在线测量,得到炉口火焰温度在整个吹炼过程中的变化趋势.结果表明,采用所提出的测温方法不仅可以在线反映转炉操作对炉口火焰温度的影响,同时也为炉口操作工人判断炉内铁水的温度提供了有效的依据.

In this paper, we propose a method used to measure the polarization state of a field with multiple polarization singularities (PSs), such as an array of PSs and PSs in vector speckle. A checkerboard is used to construct characteristic points, which makes it possible to calibrate the mismatches between pictures obtained during the rotation of a quarter-wave plate and a polarizer. Using this method a field with an array of PSs is measured. The experimental result is compared with the numerical simulation. We also carry out some data analysis. The comparison and analysis emphasize the necessity and feasibility of this method to measure the PSs.

In the basic oxygen steelmaking process, the endpoint temperature of the molten steel is one of the key factors whether the molten steel is qualified for tapping. Currently, it mainly relies on the experienced operators to control the endpoint temperature of the molten steel, and the prediction precision may vary among different operators. In order to realize the effectively end-point steel temperature prediction of the basic oxygen furnace as well as to meet the requirement of different sizes of the converter mouth, a new method based on the flame temperature measurement at the converter mouth was proposed in this paper. Firstly, a fiber-optic spectrometer system in the visible and near infrared spectral range was designed which can real-timely and effectively realize the collection of the flame radiation information at the converter mouth. Secondly, in consideration of the actual temperature of the flame and the distance between the converter and the designed system, an improved calibration method instead of the halogen lamp was adopted, and the two-color method was employed for the flame temperature measurement. Then a regression model based on the support vector machine was built with the flame temperature and several other parameters of the steel-making process as the input variables of the model. Verification experiment was carried out on 68 industrial data collected in the steel-making workshop. The results show that the prediction accuracy of this method is superior to the experienced operators, and close to the sub-lance based method. As a result, the proposed method can provide a feasible and effective solution to the end-point steel temperature prediction for those small-sized and medium-sized converters.

基于相干偏振统一理论和广义惠更斯-菲涅耳原理,研究了准均匀(QH)光束交叉偏振度(SDCP)在广义大气湍流中传输变化规律,得到光场内不同空间点之间SDCP随距离演化特征.结果显示各点偏振度(DOP)在传输中变化一致的准均匀光源,在受湍流干扰后,不同距离点对之间SDCP变化随间隔大小呈现增大和减小两个趋势,使得在某一距离处,各点对之间交叉偏振度趋于统一值,而当传输距离继续增大时,不同空间点之间交叉偏振度又显示出明显区别.光场相干度以及光强相关性也有明显不同的变化特征.所得结果揭示了光场高阶统计特性变化之间的密切联系.SDCP反映的光强波动相关的物理内涵为自由或大气空间中关联成像或偏振光通信等应用提供了理论基础.

Superfine ground calcium carbonate (GCC) produced by carbonate minerals is a widely used inorganic powder material. In order to get a finer GCC powder with narrow distribution span, the effect of rotational speed and media density on ground GCC were studied by dry grinding GCC in a planetary ball mill under different rotational speed and various media density. The grinding limit-particle size and distribution of grinding calcium carbonate were measured by centrifugal sedimentation granulometer. The structure of GCC was measured by X-ray diffraction. The result shows that low rotational speed and high-density media is conducive to get a product with smaller particle size and narrow size distribution; crystal plane (012) and (122) are more stable than (018) and (116).

A new non-contact method for predicting the endpoint carbon content of different kinds of basic oxygen furnace (BOF) vessel sizes is presented in this paper. The proposed model is based on the spectral distribution of the flame at the vessel mouth with support vector machine (SVM). Two models are constructed with SVM in this paper: a SVC model is used to classify the whole blowing phases based on the mechanism analysis, and an ɛ-SVR model is constructed to map the flame spectrum variation into the state of the molten steel in the iron bath. The simulation results on industrial datasets show that the proposed method can offer an accurate as well as convenient way to improve the performance of BOF endpoint control compared with current methods of endpoint carbon content prediction.

利用近年来发展的描述海洋湍流的空间功率谱函数,结合数值积分的方法计算并绘制了广义惠更斯菲涅耳积分中湍流项的大小随湍流参数变化的曲面图.继而通过魏格纳分布函数和光束二阶矩的定义模拟了部分相干厄米高斯(PCHG)光束的M2因子在海洋湍流中的变化情况,分析了光源参数的选择对于光束传输质量因子的影响.最后通过M2因子矩阵,计算了非旋转对称二维PCHG光束传输质量随旋转角α变化的轨迹图.发现随着传输距离的增大,在接收面上,光斑因x,y方向上模式的不同而造成轨迹图的形状的不同将逐渐消失,趋近于相同的圆形轨迹.

Based on the truncated second order moments of laser beams, the generalized beam propagation factor of truncated beams generated by a Gaussian mirror resonator (GMR) is derived. The deduced expressions for the beam factor would separately reduce to those of the truncated Gaussian, untruncated Gaussian and the untruncated beams generated by the GMR. It is shown that the value of beam factor not only relates to the reflectivity of mirrors and the ratio of beam widths to mirror spot sizes, but also closely depends on the truncated parameter. Theoretical results in this paper may provide the fundamental basis for further studies such as the analysis of the practical beam quality and the optical design of the GMR.

Propagation properties of cylindrically polarized vector (CV) beams through uniaxial crystals along the optical axis are studied. Diffracted field components of the propagating beam are derived in analytical expressions. Amplitudes of the field components, intensity distributions as well as degrees of polarization upon the propagation are depicted by numerical plots, respectively. It is shown that the field components along the x and y axis shows in different characteristics which is induced by the anisotropy of uniaxial crystals. Furthermore, effects of the initial polarization angle as well as the ratio of refractive indices on degrees of polarization are separately analyzed. Numerical results indicate that the degrees of polarization of the propagating beam generally show oscillating characteristics which certainly become much more visible during the sustained propagation. These results may provide potential applications to the optical polarization encoding or detection of unknown anisotropic scatterer by the utilization of CV beam as the incident light.

Based on the extended Huygens-Fresnel principle and generalized Stokes theory, the evolution of polarization properties of beams generated by quasi-homogenous (QH) sources propagating in clear oceanic water was studied by the use of the oceanic turbulence spatial spectrum function. The results show that the beams have similar polarization self-reconstructed behavior under different turbulence conditions in the far field, but if the propagation distance is not long enough, the degree of polarization (DOP) fluctuates with much more complexity than state of polarization (SOP) of QH beams. The self-reconstructed ability of DOP at the special distance in turbulence would get to the best value if the values of coherence of width were chosen suitably, but for SOP, it has no best value.