Multiwavelength optical pyrometer for shock compression experiments

A system for measurement of the spectral radiance of materials shocked to high pressures ( approximately 100 GPa) by impact using a light gas gun is described. Thermal radiation from the sample is sampled at six wavelength bands in the visible spectrum, and each signal is separately detected by solid-state photodiodes, and recorded with a time resolution of approximately 10 ns. Interpretation of the records in terms of temperature of transparent sample materials is discussed. Results of a series of exploratory experiments with metals are also given. Shock temperatures in the range 4000-8000 K have been reliably measured. Spectral radiance and temperatures have been determined with uncertainties of 2%.     

一种梯形干涉链可调谐光滤波器的设计与研究

结合Mach-Zehnder干涉原理和多模干涉(MMI)耦合器的散射矩阵,从理论上推导出梯形干涉链可调谐光滤波器(LTOF)输出光场的表达式,采用优化算法搜索出不同级联级数下MMI耦合器的最佳分光比,并分析了衍射阶数和电极长度对LTOF调谐输出性能的制约关系。结果表明,对应最大峰值功率,存在随级联级数增加而增大的最佳分光比;增加级联级数会导致峰值功率和3 dB带宽减小,峰值隔离度增大;电极长度为原电极的1.4倍时,可实现LTOF连续双向宽调谐的功能。通过比较,验证了理论模型及分析方法的正确性。     

Scanning optical pyrometer for measuring temperatures in hollow cathodes

Life-limiting processes in hollow cathodes are determined largely by the temperature of the electron emitter. To support cathode life assessment, a noncontact temperature measurement technique which employs a stepper motor-driven fiber optic probe was developed. The probe is driven inside the hollow cathode and collects light radiated by the hot interior surface of the emitter. Ratio pyrometry is used to determine the axial temperature profile. Thermocouples on the orifice plate provide measurements of the external temperature during cathode operation and are used to calibrate the pyrometer system in situ with a small oven enclosing the externally heated cathode. The diagnostic method and initial measurements of the temperature distribution in a hollow cathode are discussed.     

辐射光纤高温计及其系统的研究

为解决特殊情况下的高温在线测量，研制了一种辐射光纤高温计。介绍了仪表的工作原理、光滤波及测试结果的处理。     

光通讯用低PDL线性渐变衰减滤光片

计算了渐变衰减滤光片的偏振相关损耗,分析了镀膜工艺对偏振相关损耗的影响,提出了降低偏振相关损耗的方法。采用线性迭代修正法和膜厚分布可调控制技术,提高了渐变衰减滤光片的线性度。制造出线性度小于5%、偏振相关损耗小于0.08dB的高性能渐变衰减滤光片。     

在固定比较片上用上反射监控方法生产窄带干涉滤光片

采用上反射法在可更换的固定比较片上对光学镀膜过程进行监控,有利于优化离子束辅助镀膜工艺。介绍了实现这种监控方法的独特系统结构,即采用直角棱镜和自准直光路分离监控光束;对工艺过程和主要结果进行了描述。该监控系统的控制精度优于千分之五,耦合层控制精度优于百分之五,得到了和透射法监控相同的结果。     

Autofluorescence removal using a customized filter set

Quantitative fluorescence microscopy is severely hindered by intrinsic autofluorescence (AF). Endogenous fluorescent molecules in tissue and cell samples emit fluorescence that often dominates signals from specific dyes. This makes AF removal critical to the development and practice of quantitative fluorescence microscopy. In this study, we showed that AF signal could be separated from specific signal using a customized filter set. The filter set used the same excitation and beam splitter as the standard filter set, but the emission filter was red‐shifted 40–60 nm from the peak of the specific dye. This filter set configuration collected mostly AF with minimum contribution from the specific dye. A linear transformation of AF images was required to correct for the difference in exposure and filter configuration. The constants (slope and intercept) in linear transformation were obtained through a pixel to pixel comparison between AF images (no staining) obtained by the standard filter set and the customized AF filter set. After staining of specific dye, the standard filter collecting target dye spectra was used to capture both target signal and AF, whereas customized filter was used to capture only AF. AF removal was accomplished by subtracting the linear transformed AF image from the image obtained from the standard filter. To validate our approach, we examined weak staining of androgen receptor in an AF abundant prostate tissue sample. Our method revealed a similar but cleaner nuclear staining of androgen receptor in a specimen, when compared to a traditional autofluorescence removal method. Microsc. Res. Tech., 76:1007–1015, 2013. © 2013 Wiley Periodicals, Inc.     

Spacecraft attitude determination using a decoupling filter

In this paper, an algorithm for real-time attitude estimation of spacecraft motion is investigated. For efficient computation, the decoupling filter presented in this paper is accomplished by a derived pseudo-measurement from the given measurement and the decoupled state in the original system. However, the proposed decoupling filter contains model errors due to coupling terms in the system. Therefore, we develope an attitude determination algorithm in which coupling terms are compensated through an error analysis. The attitude estimation algorithm using the state decoupling technique for real-time processing provides accurate attitude determination capability under a highly maneuvering dynamic environment, because the algorithm does not have any bias errors from a truncation, and the covariance of the estimator is compensated by nonlinear terms in the system. To verify the performance of the proposed algorithm vis-a-vis the EKF (extended Kalman filter), and the nonlinear filter, simulations have been performed by varying the initial values of the state and covariance, and measurement covariance. Results show that the proposed algorithm has consistently better performance than the EKF in all of the ranges of initial state values and covariance values of measurement, and it is as accurate as the nonlinear filter. However, the convergence speed of the nonlinear filter is faster than the proposed algorithm because of the pseudo-measurement model errors in the proposed algorithm. We show that the computational time of the proposed algorithm is improved by about 23% over the nonlinear filter.     

一种日夜两用光学低通滤波器的研制

利用石英晶体的双折射效应和特殊红外截止滤光片设计并实现了一种日夜两用光学低通滤波器.该滤波器置于CCD摄像机传感器前可以有效地降低或消除离散光电探测器对不同空间频率目标成像所产生的拍频效应或条纹混叠现象,并能消除红外光对彩色还原的影响,从而提高了CCD摄像机成像的视觉效果.在分析光学低通滤波器原理和红外截止滤光片作用的基础上,设计了一种特殊的红外截止膜系,可使CCD摄像机白天成彩色像,夜晚成黑白像.采用双离子束溅射技术在石英晶体薄片上淀积了该膜系,经测试,光谱特性满足设计要求,成像效果理想.     

应用声光器件和光学滤波器实现电信号的实时子波变换

为实现输入电信号的实时传输,提出了应用声光器件和光学子波滤波器在光学范德拉格特(Vander Lugt)相关器中进行电信号实时子波变换的系统.选用的声光器件工作参数在正常布喇格区,可提高整个系统的信噪比,中心工作频率达100MHz.对变换系统中的主要参量进行了分析,认为系统需使用功率＞15 mW的激光器,且选用尺寸为1.8 mm的子波滤波器较为合适.给出了不同频率的电信号在含声光器件的二维Mexican-hat光学子波变换系统中的计算机模拟结果,表明所提出的系统能实现对输入电信号的实时子波变换.     

Energetic ion mass analysis using a radio-frequency quadrupole filter

In conventional applications of the radio-frequency quadrupole mass analyzer, the ion injection energy is usually limited to less than the order of 100 eV due to constraints on the dimensions and power supply of the device. However, requirements often arise, for example in fusion plasma ion diagnostics, for mass analysis of much more energetic ions. A technique easily adaptable to any conventional quadrupole analyzer which circumvents the limitation on injection energy is documented in this paper. Briefly, a retarding potential applied to the pole assembly is shown to facilitate mass analysis of multikiloelectron volt ions without altering the salient characteristics of either the quadrupole filter or the ion beam.     

双折射滤光器的误差分析与性能优化

由于双折射滤光器型太阳磁场望远镜中滤光器的研制质量直接影响透过带,进而影响太阳磁场的测量,本文对影响双折射滤光器透过带漂移的各种误差因素进行了分析。通过计算机编程,完全模拟了光线轨迹,精确分析了多种误差项对双折射滤光器透过带的影响。给出了引起透过带漂移、展宽、极大值和极小值变化的主要误差项。分析表明,入射角、晶体光轴倾角误差、晶体厚度误差和1/4波片光轴方位角误差影响透过带漂移;只有晶体光轴方位角误差影响透过带宽,当误差为2°时,透过带展宽了0.078%;宽视场1/2波片光轴方位角误差对极大值的影响最明显,当误差为2°时,极大值减小了0.487%;晶体光轴方位角误差、宽视场1/2波片延迟误差和1/4波片光轴方位角误差对极小值都有不同程度的影响。     

基于UAF42通用滤波芯片的50Hz陷波器设计

为了压制工业电源的干扰（如50Hz干扰），经常要在输入电路中采用陷波电路。由于传统的双T陷波电路对元件的精度和对称性要求比较高，在实际中很难调试。文中介绍的由通用滤波器芯片UAF42构成的50Hz陷波电路克服了这方面的缺点。实验结果表明：基于UAF42设计的50Hz陷波器的频率响应达到了设计要求，具有调试方便、对元件精度要求不高的优点。     

电压模式双二阶跨导线性滤波器

提出了一种新颖的基于线性跨导的双二阶电压模式滤波器,该滤波器采用单端输入五端输出的结构形式,由6个MOCCCⅡ（多端输出的电流控制电流传输器）和2个接地电容构成。在不改变电路内部结构的情况下,该滤波器能同时实现高通、低通、带通、带阻、全通滤波功能,滤波器的参数可以通过改变MOCCCⅡ的偏置电流实现电动调节,且品质因数和中心频率独立可调。面向实际电路进行了硬件实验,结果表明本文提出的电路正确有效。     

Robust proportional-integral Kalman filter design using a convex optimization method

This paper proposes a design approach to the robust proportional-integral Kalman filter for stochastic linear systems under convex bounded parametric uncertainty, in which the filter has a proportional loop and an integral loop of the estimation error, providing a guaranteed minimum bound on the estimation error variance for all admissible uncertainties. The integral action is believed to increase steady-state estimation accuracy, improving robustness against uncertainties such as disturbances and modeling errors. In this study, the minimization problem of the upper bound of estimation error variance is converted into a convex optimization problem subject to linear matrix inequalities, and the proportional and the integral Kalman gains are optimally chosen by solving the problem. The estimation performance of the proposed filter is demonstrated through numerical examples and shows robustness against uncertainties, addressing the guaranteed performance in the mean square error sense.     

An attitude determination algorithm for a spacecraft using nonlinear filter

In this paper, the algorithm for a real time attitude estimation of a spacecraft motion is investigated. The proposed algorithm for attitude estimation is the second order nonlinear filter form not containing truncation error in estimation values. The proposed second order nonlinear filter has improved performance compared with the EKF (extended Kalman filter), because the algorithm does not contain any truncation bias and covariance of the estimator is compensated by the nonlinear terms of the system. Therefore, the proposed second order nonlinear filter is a suboptimal estimator. However, the proposed estimator requires a lot of computation because of an inherent nonlinearity and complexity of the system model. For more efficient computation, this paper introduces a new attitude estimation algorithm using the state divided technique for a real time processing which is developed to provide an accurate attitude determination capability under a highly maneuverable dynamic environment. To compare the performance of the proposed algorithm with the EKF, simulations have been performed with various initial values and measurement covariances. Simulation results show that the proposed second order nonlinear algorithm outperforms the EKF. The proposed algorithm is useful for a real time attitude estimation since it has better accuracy compared with the EKF and requires less computing time compared with any existing nonlinear filters.     

Automatic segmentation of stochastic time series using a whitening filter

The problem of automatic segmentation of a stochastic time series into homogeneous data segments one cluster long is posed and solved according to the general formulation of the disorder problem. A new algorithm with cluster normalization by the variance of the generating noise is developed using an autoregression model and the minimum information divergence criterion. It is shown that the main advantage of the proposed algorithm over existing analogs is high dynamic properties. The algorithm was tested by analyzing stock market dynamics in the United States and Russia. Estimates of the admissible (threshold) level of disorder in a time series within one cluster are obtained using the Kullback-Leibler information measure.     

三明治式双折射低通滤波器的研制

为了有效抑制高于CCD或者CMOS传感器的图像采样频率而出现的莫尔条纹,研制了一种二维三明治式双折射低通滤波器(OLPF)。其主要由三片双折射晶体平板构成三明治结构,并在前、后表面分别镀上红外截止膜和增透膜。对所研制的二维水晶光学低通滤波器进行了实验测试,空间频率测试表明对莫尔条纹有良好的抑制效果。结果表明,所研制的低通滤波器具有很高的自洁净性,与后端的CCD或者CMOS传感器匹配良好,对空间高频有较强的抑制作用。     

光学低通滤波器的结构设计分析

为了设计一个较为理想的光学低通滤波器(OLPF),在分析双折射晶体的光学特性基础上,运用光学传递函数方法对各种结构的OLPF进行分析,给出了各种结构的幅频特性曲线。分析表明,晶片厚度决定滤波器的截止频率,因此采用多片式OLPF的设计可以加强滤波器对高频部分的频谱响应,从而形成较为理想的光学低通滤波器。