Far-infrared detector based on HgTe/HgCdTe superlattices

HgTe/Hg_0.05Cd_0.95Te superlattices (SLs) were grown on (112)B oriented Cd_0.96Zn_0.04 Te substrates using molecular beam epitaxy (MBE). The SLs, consisting of 100 periods of 80-Å-thick HgTe wells alternating with 77-Å-thick Hg_0.05Cd_0.95Te barriers, were designed to operate as detectors in the far-infrared (FIR) region. Infrared absorption spectroscopy, high-resolution transmission electron microscopy (TEM), Hall effect measurements, and x-ray diffraction were used to characterize the superlattice layers. A series of annealing experiments were initiated to quantify the temperature-dependent interdiffusion of the HgTe wells and Hg_0.05Cd_0.95Te barriers and consequently their degradation, which shifts the absorption edges of the SLs to higher energies, since a high-temperature ex situ anneal is normally required in order to produce the p-type material required for a photovoltaic detector. Results from infrared absorption spectroscopy, TEM, and Hall effect measurements for the annealed samples are presented. A FIR SLs single-element photoconductive (PC) device was designed and fabricated. Both material characterization and device testing have established the applicability of the HgTe/Hg_0.05Cd_0.95Te SLs for the FIR region.     

舰船尾流气泡激光回波偏振压缩探测技术研究

对舰船尾流气泡探测是对舰船进行跟踪的一种独特的方法,采用蓝绿激光对尾流气泡 探测是可行的。在分析蓝绿激光在海水介质中的衰减特性基础上,提出采用偏振压缩技术对大动态范围的激光回波信号进行压缩,提高对尾流气泡探测的精度和深度。     

离子式感烟火灾探测器研制及应用技术探讨

几十年来离子式感烟探测器一直在火灾探测领域占居主导地位，但由于光电式感烟探测器近年来发展使其受到挑战。本文从两者各自探测原理、探测性能的差异，工作寿命诸方面进行分析比较，对于人们就核辐射放射性危害的误解释疑，并就离子式感烟探测器目前自我完善，发展方向和途径作探讨和研究。     

基于偏振的光矩阵开关

提出了一种新型的基于偏振的光矩阵开关方法 ,通过控制光的偏振态实现严格无阻塞连接。以 4× 4光矩阵开关为例 ,详细给出了其节点开关和交换网络的实现方案。并对该 4× 4光矩阵开关进行实测 ,证明该方法制作的小规模光矩阵开关具有插损低 ,串话小 ,开关时间中等 ,性能稳定 ,工艺成熟等特点。     

Factors Affecting Linearity and Response of Flame Ionization Detector

The application of gas chromatography to the analysis of both major and minor compounds in a sample requires a detector of high sensitivity and wide response range, such as a flame ionization detector. Response, linearity, and noise of the flame ionization detector are discussed and the effect of parameters, e.g., flow rates of the carrier, fuel gases, and sample capacity on the response of the detector are investigated. Also, it is necessary to know whether its response is strictly linear over the required range. This research aims to study the response characteristics of flame ionization detectors and their linear range. The optimum operating conditions have also been investigated in some detail.     

Detection of Weak Gravitational Pulses in the Minimum Mode Regime

An amplitude algorithm is considered for detecting weak and rare gravitational pulses in the minimum mode regime on a background of arbitrary additive non-Gaussian noise under conditions of parametric a priori uncertainty.     

核探测器的进展

本文介绍了几种基本核探测器的国外最新进展。     

CONCENTRATION POLARIZATION ANALYSIS AT THE ENTRANCE REGION OF A FLAT SHEET PERVAPORATION MODULE FOR VOC REMOVAL

Concentration polarization is a phenomenon that is inherent in all membrane separation processes, which is difficult if not impossible to measure experimentally. Concentration polarization in a pervaporation module causes flux decline and is therefore an important issue in predicting the performance of the membrane unit for evaluation and optimization. Short-form (small L/D ratio) membrane configurations, commonly used for membrane evaluations or certain material separations, compound the complexity of process modeling that addresses concentration polarization since a substantial portion of the membrane flow channel would be considered as an “entrance region” based on the flow profile that is not fully developed. This article employed the classic boundary layer theory, combined with mass transfer phenomena in a pervaporation process that is used in volatile organic compound (VOC) removal from contaminated water sources, to theoretically analyze the concentration polarization severity in the entrance region of a flat sheet membrane module.     

选择适用原理的气体探测器

气体探测器是当有气体泄露或危险将要发生时,提醒有关人员采取相关措施以预防事故发生,介绍了如何正确地使用气体探测器。     

Position Adaptive Measurement Model for Double-four Quadrant Photoelectric Detector

A modeling method of the support vector machine combined with matrix optics is considered; a complete new measurement model for double-four quadrant photoelectric detector is built. According to the analysis of the received light spot size and its motion with the changes of the defocusing amount of detector photosensitive surface and the detector position attitude in the optical path, a mathematic expression of photoelectrical conversion is given, which can be applicable to random setting position of the detector at any time. Based on least square support vector machine （LS SVM）, the mapping relationship among the output signal linear characteristic parameters （zero neighborhood gradient and intercept）, the defocusing amount of the detector and the installation position attitude angle is established. Thus, the multiple dimensional high accuracy measuring and adjusting control system can be left out, and adaptive measurement of the detector parameters can be realized. Compared with existed measurement model and method, the presented model has the advantages of more clear physical meaning, closer to work mechanism of detector, acquiring more complete sample data and wiping out the dead spots or bad spots in measurement. And the accuracy of displacement measurement is increased to 3μm. At the same time, this measurement mode provides a technical shortcut for three-dimensional small angle measurement.