WZZ-2S旋光仪故障维修特例

通过2则WZZ-2S旋光仪测量时不工作,测量显示不准确特殊故障的维修过程,向仪器维修人员介绍快捷检测同类仪器故障的检修方法.     

Cosmic Microwave Background Polarization Detector with High Efficiency, Broad Bandwidth, and Highly Symmetric Coupling to Transition Edge Sensor Bolometers

We describe a prototype detector system designed for precise measurements of Cosmic Microwave Background polarization. The design combines a quasi-optical polarization modulator, a metal feedhorn, a superconducting planar microwave circuit, and a pair of transition-edge sensor (TES) bolometers operating at <100 mK. The circular feedhorn produces highly symmetric beams with very low cross-polarization. The planar circuit preserves symmetry in coupling to bolometers measuring orthogonal polarizations. We implement the circuit with superconducting niobium transmission lines. Three-dimensional interfaces between the planar circuit and waveguides leading to feedhorn and backshort have been carefully designed with electromagnetic simulations. Power is thermalized in resistors and conducted to bolometers via normal electrons. Our system is designed for a 29–43 GHz signal band. We have tested individual circuit elements in this frequency range. Fabrication of a full single-pixel system is underway.      

Design of FPGA based high-speed data acquisition and real-time data processing system on J-TEXT tokamak

Tokamak experiment requires high-speed data acquisition and processing systems. In traditional data acquisition system, the sampling rate, channel numbers and processing speed are limited by bus throughput and CPU speed. This paper presents a data acquisition and processing system based on FPGA. The data can be processed in real-time before it is passed to the CPU. It provides processing ability for more channels with higher sampling rates than the traditional data acquisition system while ensuring deterministic real-time performance. A working prototype is developed for the newly built polarimeter–interferometer diagnostic system on the Joint Texas Experimental Tokamak (J-TEXT). It provides 16 channels with 120 MHz maximum sampling rate and 16 bit resolution. The onboard FPGA is able to calculate the plasma electron density and Faraday rotation angel. A RAID 5 storage device is adopted providing 700 MB/s read–write speed to buffer the data to the hard disk continuously for better performance.     

Polarised light stress analysis and laser scatter imaging for non-contact inspection of heat seals in food trays

This paper introduces novel non-contact methods for detecting faults in heat seals of food packages. Two alternative imaging technologies are investigated; laser scatter imaging and polarised light stress images. After segmenting the seal area from the rest of the respective image, a classifier is trained to detect faults in different regions of the seal area using features extracted from the pixels in the respective region. A very large set of candidate features, based on statistical information relating to the colour and texture of each region, is first extracted. Then an adaptive boosting algorithm (AdaBoost) is used to automatically select the best features for discriminating faults from non-faults. With this approach, different features can be selected and optimised for the different imaging methods. In experiments we compare the performance of classifiers trained using features extracted from laser scatter images only, polarised light stress images only, and a combination of both image types. The results show that the polarised light and laser scatter classifiers achieved accuracies of 96% and 90%, respectively, while the combination of both sensors achieved an accuracy of 95%. These figures suggest that both systems have potential for commercial development.     

Hard X-ray polarization measured with a Compton polarimeter at synchrotron radiation facility

A hard X-ray polarimeter with CdTe detectors has been developed for measurement of the degree of X-ray polarization at synchrotron radiation facilities. It utilizes 90° Compton scattering from the low Z targets. Measurements were performed at both facilities of the beamline BL38B1 in SPring-8 and the beamline BL14A in KEK-PF. The degrees of X-ray polarization for 20 keV X-rays are 99% and 82% at the BL38B1 in SPring-8 and BL14A in KEK-PF, respectively. The polarization degrees in the energy range of 15 and 40 keV correspond to 99.6±0.2% and 96.1±0.2% at the beamline BL38B1 in SPring-8. The analyzing power of the polarimeter was estimated by the Monte Carlo simulation with EGS4. The synchrotron radiation facilities provide highly polarized X-ray beams at energies above 15 keV.     

北京同步辐射软X射线偏振测量装置及其应用

在北京同步辐射装置(BSRF)设计建造了-套基于多层膜偏振元件的软X射线偏振测量分析装置,可工作在双反、双透、前反后透和前透后反四种工作模式,既可作为偏振测量装置,用于同步辐射光束线和多层膜偏振元件偏振特性测量,也可作为通用反射率计,用于多层膜和薄膜的反射或透射率测量,又可用于磁性材料的磁光效应研究等.利用自行研制的装置和光学元件对BSRF的3W1B光束线的偏振特性进行了系统的测量.测量结果指出,在206 eV时,输出光的线偏振度从起偏前的O.585上升到起偏后的0.995,同步光的线偏振度得到极大改善.利用非周期宽带Mo/Si多层膜开展了铁磁性材料的磁光法拉第效应测量,获得了Ni薄膜3p边附近(60-70 eV)的法拉第旋转角度,最大偏转角度在65.5 eV和68 eV分别为1.85±0.19°和-0.75±0.09°.     

静态自动旋光仪

静态自动旋光仪主要原理是利用法拉第效应使光矢量转动寻找消光位置,把机械转动的测量转变为电学量的测量,易于实现自动测量.其主要特点是节省了角度测量系统,同时必须有一套标准旋光管进行标定以消除系统误差.静态自动旋光仪测量旋光标准石英管时的扩展不确定度可以达到U=0.02°,置信因子k=2.     

利用热红外偏振成像技术识别伪装目标

介绍了热红外偏振测量的原理,采用利用偏振信息在红外图像中识别伪装遮障的方法研制了一台热红外偏振成像仪,编写了偏振信息分析软件。利用该系统对地物背景（土壤）中的不同种类金属目标板及红外伪装遮障进行了热红外偏振成像探测实验。结果表明：在利用热红外偏振探测系统获得的Stokes矢量图中, 地物背景、金属目标板及红外伪装遮障的热红外偏振特性各不相同,并且和其红外辐射强度无关,相对红外强度探测更容易从地物背景中识别出金属目标板及红外伪装遮障。     

Correcting systematic errors in high-sensitivity deuteron polarization measurements

This paper reports deuteron vector and tensor beam polarization measurements taken to investigate the systematic variations due to geometric beam misalignments and high data rates. The experiments used the In-Beam Polarimeter at the KVI-Groningen and the EDDA detector at the Cooler Synchrotron COSY at Jülich. By measuring with very high statistical precision, the contributions that are second-order in the systematic errors become apparent. By calibrating the sensitivity of the polarimeter to such errors, it becomes possible to obtain information from the raw count rate values on the size of the errors and to use this information to correct the polarization measurements. During the experiment, it was possible to demonstrate that corrections were satisfactory at the level of 10⁻⁵ for deliberately large errors. This may facilitate the real time observation of vector polarization changes smaller than 10⁻⁶ in a search for an electric dipole moment using a storage ring.