Fully integrated InGaAs/InP single-photon detector module with gigahertz sine wave gating

InGaAs/InP single-photon avalanche diodes (SPADs) working in the regime of GHz clock rates are crucial components for the high-speed quantum key distribution (QKD). We have developed for the first time a compact, stable, and user-friendly tabletop InGaAs/InP single-photon detector system operating at a 1.25 GHz gate rate that fully integrates functions for controlling and optimizing SPAD performance. We characterize the key parameters of the detector system and test the long-term stability of the system for continuous operation of 75 h. The detector system can substantially enhance QKD performance and our present work paves the way for practical high-speed QKD applications.     

Performance trade-offs in single-photon avalanche diode miniaturization

Single-photon avalanche diodes (SPADs) provide photons' time of arrival for various applications. In recent years, attempts have been made to miniaturize SPADs in order to facilitate large-array integration and in order to reduce the dead time of the device. We investigate the benefits and drawbacks of device miniaturization by characterizing a new fast SPAD in a commercial 0.18 microm complementary metal oxide semiconductor technology. The device employs a novel and efficient guard ring, resulting in a high fill factor. Thanks to its small size, the dead time is only 5 ns, resulting in the fastest reported SPAD to date. However, the short dead time is accompanied by a high after-pulsing rate, which we show to be a limiting parameter for SPAD miniaturization. We describe a new and compact active-recharge scheme which improves signal-to-noise tenfold compared with the passive configuration, using a fraction of the area of state-of-the-art active-recharge circuits, and without increasing the dead time. The performance of compact SPADs stands to benefit such applications as high-resolution fluorescence-lifetime imaging, active-illumination three-dimensional imagers, and quantum key distribution systems.     

便携式阻抗测量仪的研制与应用

本研究建立涂层性能快速测试方法并研制相关测试仪器。该仪器由一台便携式的交流阻抗测试仪及相关软件构成,可作为一般的交流阻抗测试仪进行全频率区间的交流阻抗测试,用于研究涂层的保护性能和失效过程;也可在工程应用现场对涂层性能进行快速测试,实现对涂层服役性能的快速评价。     

用于智能结构自诊断、自修复的新型光纤传感测试仪

介绍了空心光纤的传感性能及其在力学量测试中的应用，并对传感机理进行了简要地分析，主要侧重于空心光纤传感测试仪的研制，并通过实验验证了传感器测试仪用于智能结构损伤位置自诊断以及损伤处自修复的可行性。     

Design and commissioning of a high magnetic field muon spin relaxation spectrometer at the ISIS pulsed neutron and muon source

The high magnetic field (HiFi) muon instrument at the ISIS pulsed neutron and muon source is a state-of-the-art spectrometer designed to provide applied magnetic fields up to 5 T for muon studies of condensed matter and molecular systems. The spectrometer is optimised for time-differential muon spin relaxation studies at a pulsed muon source. We describe the challenges involved in its design and construction, detailing, in particular, the magnet and detector performance. Commissioning experiments have been conducted and the results are presented to demonstrate the scientific capabilities of the new instrument.     

High temperature faraday balance for in situ measurement of magnetization in transition metal oxides

We report the design of a Faraday balance that can be used to measure the magnetization of transition metal oxides at high temperatures and under controlled atmosphere. The instrument is sufficiently sensitive and stable to quantify the magnetic force on diamagnetic and paramagnetic samples at temperatures up to 1000 degrees C and in oxygen partial pressures as low as 100 ppm. We demonstrate the performance of the instrument by presenting preliminary magnetic measurements of lanthanum strontium cobalt oxide (La1-xSr(x)CoO3-delta) and aluminum oxide (Al2O3).     

基于嵌入式技术的机械设备点检仪

点检是掌握设备运行状态的重要手段.点检仪由数据采集、人机交互、通信和存储等单元组成;采用ARM微处理器,设计了数据存储、信号采集等硬件电路;构建了嵌入式Linux操作系统,编写了设备驱动和仪器应用程序,以实现对振动、温度、设备条码信息、观察量、抄表量的采集和管理;仪器通过USB接口与上位机通信;点检仪小巧、便携、使用方便,和后端软件一起组成的点检管理系统可有效提高设备管理的自动化水平.     

Custom single-photon avalanche diode with integrated front-end for parallel photon timing applications

Emerged as a solid state alternative to photo multiplier tubes (PMTs), single-photon avalanche diodes (SPADs) are nowadays widely used in the field of single-photon timing applications. Custom technology SPADs assure remarkable performance, in particular a 10 counts/s dark count rate (DCR) at low temperature, a high photon detection efficiency (PDE) with a 50% peak at 550 nm and a 30 ps (full width at half maximum, FWHM) temporal resolution, even with large area devices, have been obtained. Over the past few years, the birth of novel techniques of analysis has led to the parallelization of the measurement systems and to a consequent increasing demand for the development of monolithic arrays of detectors. Unfortunately, the implementation of a multidimensional system is a challenging task from the electrical point of view; in particular, the avalanche current pick-up circuit, used to obtain the previously reported performance, has to be modified in order to enable high parallel temporal resolution, while minimizing the electrical crosstalk probability between channels. In the past, the problem has been solved by integrating the front-end electronics next to the photodetector, in order to reduce the parasitic capacitances and consequently the filtering action on the current signal of the SPAD, leading to an improvement of the timing jitter at higher threshold. This solution has been implemented by using standard complementary metal-oxide-semiconductor (CMOS) technologies, which, however, do not allow a complete control on the SPAD structure; for this reason the intrinsic performance of CMOS SPADs, such as DCR, PDE, and afterpulsing probability, are worse than those attainable with custom detectors. In this paper, we propose a pixel architecture, which enables the development of custom SPAD arrays in which every channel maintains the performance of the best single photodetector. The system relies on the integration of the timing signal pick-up circuit next to the photodiode, achieved by modifying the technological process flow used for the fabrication of the custom SPAD. The pixel is completed by an external standard CMOS active quenching circuit, which assures stable timing performance at quite high count rate (>1 MHz).     

High throughput optical readout of dense arrays of nanomechanical systems for sensing applications

We present an instrument based on the scanning of a laser beam and the measurement of the reflected beam deflection that enables the readout of arrays of nanomechanical systems without limitation in the geometry of the sample, with high sensitivity and a spatial resolution of few micrometers. The measurement of nanoscale deformations on surfaces of cm(2) is performed automatically, with minimal need of user intervention for optical alignment. To exploit the capability of the instrument for high throughput biological and chemical sensing, we have designed and fabricated a two-dimensional array of 128 cantilevers. As a proof of concept, we measure the nanometer-scale bending of the 128 cantilevers, previously coated with a thin gold layer, induced by the adsorption and self-assembly on the gold surface of several self-assembled monolayers. The instrument is able to provide the static and dynamic responses of cantilevers with subnanometer resolution and at a rate of up to ten cantilevers per second. The instrumentation and the fabricated chip enable applications for the analysis of complex biological systems and for artificial olfaction.     

基于遗传算法的自动平衡数字式显示仪表的PID控制器设计

在介绍数字自动式字显示仪表工作原理的基础上，分析了显示仪表各部分结构参数对系统动态性能的影响，并建立了数学模型。根据系统动态性能指标的要求，基于遗传算法设计了一种PID控制器，并利用MATLAB语言对该数学模型进行了仿真。仿真结果表明：该仪表具有无超调量、调节时间短、PID参数整定简单等优点，能满足实际应用对动态性能要求。     

ESQUIRE-LC离子阱LC/MS~n

ESQUIRE-LC离子阱LC/MS~n是将惠普(HP)与布鲁克(Bruker)的尖端技术相结合的高效液相色谱/质谱(LC/MS~n)系统。惠普公司成功的1100系列HPLC和先进的电喷雾电离/大气压化学电离(ESI/APCI)离子源与布鲁克公司最新的多极离子阱MS和MS~n分析器完美结合在一起。ESQUIRE-LC是一种先进的自动化程度最高的液质联用仪。本文是对该仪器的性能特点、技术指标及应用的简要介绍。     

NMR probe for pressure-jump experiments up to 250 bars and 3 ms jump time

We describe the design and performance of a pressure-jump instrument for time-resolved NMR experiments. Initial pressure of up to 250 bars can be produced by means of a HPLC pump and distilled water as a pressure-transmitting liquid. Fast pressure release at a time resolution of 3 ms is achieved using a fast acting valve driven by a piezostack close to the sample chamber. The pressure-jump cell is placed together with two valves in an especially designed NMR probe, which can be used in standard spectrometers with wide-bore magnets. All functions of the instrument are personal computer controlled. The equipment is designed for investigations on systems of biological interest, especially lipid-water dispersions. A theoretical consideration implies that probably the limited speed of valve opening determines the lower boundary of the jump time. The performance is illustrated by time-resolved NMR spectra across the phase transition of a phospholipid-water dispersion after a pressure jump from 100 bars to atmospheric pressure.     

自动平衡式数字显示仪表的建模与仿真

在阐述自动平衡式数字显示仪表工作原理的基础上，详细分析了显示仪表各部分结构参数对系统动态性能的影响，并建立了该系统的数学模型。根据系统动态性能指标的要求，利用软件设计了3种不同的控制器，并利用MAT—LAB语言对该数学模型进行了仿真，最后分析了3种不同控制规律下的系统模型的仿真结果。仿真结果表明：引入速度反馈(PD控制器)的自动平衡式数字显示仪表具有超调量小、调节时间短、软件实现简单等优点，能满足实际应用对自动平衡式数字显示仪表的动态性能要求。     

Dynamic light scattering in turbid nonergodic media

We here present a new device based on dynamic light scattering (DLS) for measuring kinetics in turbid and nonergodic systems. This flat cell light scattering instrument has been developed in our laboratory and is based on an original flat cell instrument employing cells of varying thickness in order to measure the static structure and dynamics of a system. The smallest cell thickness is 10 microm. To this original instrument, we have integrated the three-dimensional (3D)-DLS technology as well as the echo method, and in comparison with other 3D-DLS instruments, ours show the best performance; the maximum intercept was 0.6 as opposed to 0.15 for regular 3D-DLS devices (recently we reached beta=0.75). This was made possible by using crossed polarization filters for the two laser beams, thereby allowing the scattered light from both laser beams to be decoupled and the intercept to no longer be limited at the theoretical value of 0.25. The maximum weight fraction of the sample that is measurable with such a setup is more than ten times higher than with a standard 3D-DLS setup or with the flat cell instrument without the 3D technology. Consequently, with the 3D-DLS flat cell instrument presented here, it truly becomes possible to investigate turbid systems. Moreover, the echo method was integrated to enable measurements of nonergodic systems. Here, a new mechanical design of the echo-DLS component was necessary due to the different geometries of the flat cell in comparison with that of a standard cylindrical cell. The performance of our echo device was compared to that of our multispeckle instrument, and the results were in good agreement for correlation times up to 30,000 s and more. The main limitation of this instrument in its current version is the maximum scattering angle of about 50 degrees (or 30 degrees if echo is used).     

热电离飞行时间质谱仪性能评价

本工作介绍了实验室自制的热电离飞行时间质谱仪（TI-TOF-MS）的基本结构、仪器运行参数和性能特点等。离子源产生的离子在推斥电压作用下进入聚焦透镜,然后进入垂直引入反射式的飞行时间质量分析器,最后到达检测器。信号通过数据采集卡处理后传输给计算机,采用编写的LabVIEW软件采集信号和处理数据。结果表明：仪器可测量的质量范围为m/z 6~320,在m/z 208位置的质量分辨率可达2000,2 h质量稳定性为7.76×10^-5,测量²⁰⁷Pb/²⁰⁶Pb、²⁰⁷Pb/²⁰⁶Pb和²⁰⁷Pb/²⁰⁶Pb同位素比值的精密度分别为0.85%、0.27%和0.55%。该仪器在研究热电离离子源电离行为、同位素比值测定和多原子离子信号监测等方面具有广泛的应用前景。     

Microcomputer-based multiplexer for performing depth profiling with an Auger electron spectrometer

A microcomputer-based instrument for the automated profiling of samples with an Auger electron spectrometer and Ion Gun is described. The instrument records the changing heights of spectral peaks as it controls spectrometer scanning over predefined windows. Interactive front panel controls are used to set up a run and control profiling operations. The generated data is stored on a magnetic disk for later analysis and plotting. Implementation of the device using an LSI-11 microcomputer and interfacing hardware is detailed, along with the characteristics of the fortran iv driving software. An exploration of future capabilities and applications of the multiplexer is also given.     

Print your atomic force microscope

Progress in scanning probe microscopy profited from a flourishing multitude of new instrument designs, which lead to novel imaging modes and as a consequence to innovative microscopes. Often these designs were hampered by the restrictions, which conventional milling techniques impose. Modern rapid prototyping techniques, where layer by layer is added to the growing piece either by light driven polymerization or by three-dimensional printing techniques, overcome this constraint, allowing highly concave or even embedded and entangled structures. We have employed such a technique to manufacture an atomic force microscopy (AFM) head, and we compared its performance with a copy milled from aluminum. We tested both AFM heads for single molecule force spectroscopy applications and found little to no difference in the signal-to-noise ratio as well as in the thermal drift. The lower E modulus seems to be compensated by higher damping making this material well suited for low noise and low drift applications. Printing an AFM thus offers unparalleled freedom in the design and the rapid production of application-tailored custom instruments.     

Measurement of Lubrication Condition in Rolling Element Bearings

Rolling element bearing performance is strongly dependent upon the degree of separation of rolling elements and raceways by means of a lubricant film. In critical applications, it is important to know the degree of surface separation, but the operating conditions are often not known in sufficient detail to make accurate calculations and the effects of some conditions are not yet adequately understood.

This paper describes a new instrument for directly measuring lubrication conditions in rolling element bearings in their application and in the laboratory. The capabilities of the instrument are demonstrated by comparison between calculated and measured degree of separation in a special test setup where details of the operating condition are known. The new instrument is a valuable tool for achieving optimum initial lubrication condition in a bearing application and in monitoring for lubrication failure.     

基于小麦蛋白测定的国产近红外光谱分析仪模型性能评价

针对新研制的光栅型国产近红外光谱分析仪进行性能测试评价。测试样品选用已知粗蛋白化学值的72份小麦样品,测试仪器选用2台S450型国产近红外光谱分析仪和1台进口傅里叶变换近红外光谱分析仪,测试项目包括:仪器模型性能对比、仪器模型稳定性测试、台间仪器模型传递测试。测试数据表明,新型国产近红外光谱分析仪模型指标达到进口仪器水平,模型传递性能良好,可满足近红外光谱分析技术的实际应用需求。     

龙门式钢管喷标机的研制

介绍了龙门式自动钢管喷标机的主要生产工艺、性能，系统的总体机械设计、电气设计以及软件设计方案；给出了相关的设计原理和实现策略以及实际生产的结果。实际表明，该设备的设计是可行的，有效地提高了钢管表面喷印效果。