共查询到20条相似文献,搜索用时 125 毫秒
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建立了半导体激光器电光取样系统。选择1.3μm,InGaAs增益开关半导体激光器作为取样光源,利用微带GaAs衬底的纵向电光效应作为电光取样器,测量了InGaAs/InP雪崩二极管的脉冲响应特性。分析表明,本系统具有0.35mV/√Hz的电压灵敏度和9ps的时间分辨率。 相似文献
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产生24比特彩色的高速成像仪EastmanKodak's运动分析系统分部研制的高分辨率彩色(HRC)运动分析仪能以高达1000帧/S的速率记录24比特彩色图像。该器件能以数字格式存储的帧数大约为5456,分析仪能以高达1000帧/S的速率用正向或反向... 相似文献
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利用高分辨光谱测量系统,根据杂质离子谱线OⅡ464.2nm,CⅢ464.7nm和氢Hα谱线的多普勒位移,测量了CT-6B托卡马克等离子体角向转动速度的径向分布.结果表明:杂质离子的角向转动速度的方向在等离子体内部为电子逆磁漂移方向,其线速度在小半径约9cm处达到极大值3.5km/s;在接近孔阑r=10cm处,反转为离子逆磁漂移方向.由此导出等离子体内部的径向电场向里,其最大值为18V/cm.中性氢原子只存在其方向为电子逆磁漂移方向的角向转动分量,其数值较杂质离子谱线所得结果要低.最后对所得的结果作了初步的讨论
关键词: 相似文献
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超导体/半导体界面处的电子相互作用 总被引:1,自引:0,他引:1
介绍了低维系统物理与器件研究领域内最近兴起的一个十分引人注目的交叉学科课题:超导体/半导体/超导体双异质结构中电子在超导体/半导体界面处的相互作用行为,包括超导邻近效诮及Josephson场效应晶体管的探索研究,此外,还讨论了此领域内一个重要物理问题-Andreev反射。 相似文献
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在HAc溶液中,As存在下,Os以KBrO3氧化溴甲酚绿具有强烈的催化作用,据此建立了催化光度法测定痕量Os的新方法,方法的灵敏度为3.86×10^12g/mLOs,线性范围为3-30ng/10mL。用于合成自然铂,自然钯矿中锇的测定,结果满意。 相似文献
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电子俘获材料的光学性质及光存储机制研究 总被引:23,自引:7,他引:16
报道在硫化锶中掺入Eu、Sm和Ce、Sm两种激活剂的具有良好的光存储功能的新型光子学材料。以紫外到绿光之间不同波长的光写入信息,用近红外光读出,读出信号为橙色或绿色发光。系统的光响应速率小于20ns,写/读/擦速度快;光存储机制为电子的俘获和释放,无热效应,比目前的其他光存贮系统更优越。 相似文献
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A laser-based measurement system for evaluation of the scraping workpiece quality that can eliminate contact-induced measurement errors and increase measurement accuracy is proposed. The laser-based measurement system comprises a light-scattering-type triangulation laser, a computer numerical control (CNC) machine tool, and an analog-to-digital (A/D) card. The triangulation laser measures the depth of the scraping spots and the CNC machine tool locates their position. The 3D data of the scraping workpiece is then drawn using the least squares method. Cast iron and Turcite workpieces can be measured. Five parameters of the scraping workpiece, namely peak points per square inch, percentage of points, distribution of heights of points or depth of surroundings, edge shape of the grooves, and flatness, can be evaluated. The scanning rate and sampling rate of the laser-based measurement system are 100 mm/s and 10 KHz, respectively. In the future, an appliance machine based on the proposed system will be designed for the on-line detection of scraping workpieces. 相似文献
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Using a single high-speed camera and a frequency modulated laser, a novel approach is presented for fast velocity field measurements in unsteady spray flows. The velocity range is from zero up to several 100 m/s, which requires a high measurement rate and a large dynamic. Typically, flow measurements require to seed tracer particles to the fluid. A paradigm shift to seeding-free measurements is presented. The light scattered at the phase boundaries of the fluid droplets is evaluated. In order to validate the high-speed measurement system, a detailed uncertainty analysis is performed by means of measurements as well as simulations. Thereby, variations of the scattered light intensity, which are based on the high temporal velocity gradients, are found to be the main contribution to the uncertainty. The eventually measurement results, obtained at a measurement rate of 500 kHz, exhibit spray velocities ranging from 0 m/s up to 400 m/s in less than 1 ms, and the detection of unsteady and irregular flow phenomena with a characteristic time of several μs is achieved. This demonstrates the high measurement rate, the high temporal resolution and the large measurement range of the proposed high-speed measurement system. 相似文献
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S. B. Andersson 《Applied physics. B, Lasers and optics》2011,104(1):161-173
We describe an algorithm for using a confocal microscope for tracking single fluorescent particles diffusing in three dimensions.
The algorithm uses a standard confocal setup and directly translates each fluorescence measurement into an actuator command.
Through physical simulations, we illustrate 3-D tracking in both stage scanning and beam scanning confocal systems. The simulated
stage scanning system achieved tracking of particles diffusing in 3-D with coefficients up to 0.2 μm2/s when the average fluorescence intensities was less than 1.84 counts per measurement cycle (corresponding to less than 18,400
counts per second) in the presence of background fluorescence with a rate of 5,000 counts per second. Increasing the fluorescence
intensity to approximately 193 counts per measurement cycle (1,930,000 counts per second) allowed the system to track up to
particles diffusing with coefficients as large as 0.7 μm2/s. The beam steering system allowed for faster motion of the focal volume of the microscope and successfully tracked particles
diffusing with coefficients up to 0.7 μm2/s with fluorescence measurement intensities of approximately 0.189 counts per measurement cycle (37,570 counts per second)
and with coefficients up to 90 μm2/s when the fluorescence intensity was increased to 19 counts per measurement cycle (3,807,500 counts/sec). 相似文献
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极化率测量装置是极化3He系统的重要组成部分之一.本文介绍了一套在极化3He系统上搭建的激光探测自由感应衰减核磁共振(FID NMR)信号的实验装置,该装置有望为3He极化率的高精度实时测量提供新的途径.激光探测法的原理是法拉第旋光效应,该方法使用一束线偏振光探测极化3He磁矩绕主磁场进动的FID信号,实验结果表明相较于拾波线圈探测方法,激光探测方法的信噪比提高了106%,对3He的极化率测量更精确.该探测方法有望替代传统的拾波线圈,广泛地应用于3He极化系统的极化率测量或精密测量实验中. 相似文献
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Determination of the regression rate of a fast moving solid/liquid interface using ultrasonics 总被引:12,自引:0,他引:12
This paper reports on an ultrasonic measurement system and its application for in situ real-time measurement of very fast regression rates (>200 mm/s) of the melting interface (RRMI) produced when burning particular metals such as aluminium at high pressures. The RRMI is referred to as the rate at which a solid/liquid interface moves along a metallic rod while burning in an oxygen-enriched atmosphere. The ultrasonic transducer and associated equipment used to drive and record the transducer's output signal and conversion of this output into a regression rate is described. Aluminium rods were burned in pure gaseous oxygen at pressures up to 69 MPa (10,000 psia) where the RRMI was calculated at 204+/-2 mm/s. Other tests with a variety of sample materials, geometric shapes and test conditions were also conducted. The resulting RRMI's calculated with the ultrasonic measurement system compare excellently with rates obtained using a visual review of the same tests and with published results (where available). 相似文献
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针对国产MEMS加速度计MSA009的工作原理和输出特性,设计了一种测试系统,以Spartan II系列的XC2S30为主控芯片,并结合外围电路搭建了测试系统。基于ISE 8.1平台,采用VHDL硬件描述语言实现了对A/D转换芯片和Flash的控制,完成了加速度计输出信号的实时采集与存储。利用高精度三轴位置速率转台对测试系统进行试验验证,并对所采集的数据进行分析处理。经试验论证,该测试系统实现了对MSA009加速度计的测试,具有良好的实用性、稳定性。 相似文献
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全光取样示波器是研究与开发超高速光通信系统和光子交换网络的关键性测试仪器设备. 本文简介了我们自行设计和研制出的超宽带全光取样示波器设备的实验样机系统, 并报道了我们已取得的初步实验结果. 采用自主研发的高稳定性被动锁模飞秒光纤激光器作为该光学示波器的光脉冲取样源, 我们通过利用高度非线性光纤中的四波混频效应, 成功地实现了对脉宽为1.8ps、重复频率分别为10GHz和40GHz的光脉冲信号的全光取样. 然后通过数字信号处理和计算机图形处理, 得到了再现后的超短光脉冲信号波形, 并测出了其脉冲宽度值为2.3ps. 借助于该光学取样示波器实验样机, 我们还成功地完成了对脉宽为1.8ps、经过伪随机数据序列调制后的10Gbit/s和40Gbit/s光数据信号眼图的精确测量. 这是我国首次报道有关超宽带全光取样示波器设备的实际研制工作及其相应的实验测试结果. 所得到的有关超短光脉冲信号波形的测试结果也与用70GHz宽带电子示波器和超快光电探测器组成的常规光电测量系统所获得的结果进行了比较, 清楚地表明了我们研制出的全光取样示波器实验样机比后者具有更高的时间分辨率和更大的测量带宽. 相似文献
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Within quantum mechanics, a complete set of commutting observables can be found which describe the attributes of a system at a given time. However, the correct way to describe attributes of a system in time is still an open question. We discuss the difficulties in extending the standard approach of quantum mechanics to describe attributes of a system in time. We find that measuring when an event occurred and measuring that it occurred, are complimentary in Bohr's sense. To exemplify the differences between measurements at a given time and in time, we will compare Rovelli's recent proposal (quant-ph/9802020), to determine “at what time does a measurement occurred” with another model of a continuous measurement in time. Rovelli's scheme answers the question “has the measurement already occurred at a certain time?”, but does not answer to the more difficult question: “when did the measurement occur?” We also discuss the use of the probability current to measure the time at which a particle arrives to a certain location. 相似文献