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1.
为了满足在极低和较高光功率范围内对光信号的探测,提出了基于硅光电倍增管(SiPM)的弱光检测系统,该系统包含自动调节偏压电路、电流-电压转换电路、小信号放大电路和滤波电路。测量不同偏压下SiPM的输出与入射光信号之间的关系,实验结果显示,偏压对SiPM的输出有很大影响,不同偏压下,SiPM的探测能力和探测范围都不相同。此外,该系统对25 pW到1.75μW的光信号都有响应,能在极低和较高光功率范围内对光信号进行连续探测。  相似文献   

2.
针对暗物质粒子探测卫星(DMPES)锗酸铋(BGO)量能器探测单元的标定需要,设计了一种用发光二极管(LED)作为光源的闪烁晶体荧光模拟器。首先,利用光电倍增管(PMT)测量BGO晶体在宇宙线辐射下的荧光脉冲,对脉冲波形建模拟合,并将波形存储到可编程信号发生器中。然后,选择一种峰值波长与BGO晶体的荧光发射波长相近,且其光通量与工作电流的线性度较好的LED,设计LED驱动电路,令LED的工作电流与模拟器输入的模拟电压信号幅度成正比。最后,利用信号发生器输出模拟的BGO晶体荧光脉冲波形至驱动电路,使LED发光,并利用积分球将LED的荧光通过光纤均匀地输出到多个PMT。实验结果表明:模拟器光脉冲测试结果与对BGO晶体实际测试的结果相似,光强覆盖PMT的2,5,8个打拿极(Dynode)输出,动态范围达4.11×103倍,满足暗物质粒子探测卫星BGO量能器地面检测系统的需求。该荧光模拟器也可用于同类闪烁晶体探测器系统的检测和标定。  相似文献   

3.
对于光谱仪的信号采集系统的两个关键技术指标是微弱光电信号的处理和多通道数据的同步采集和传输。在分析信号采集的工作原理基础上,结合工程应用,研究了用于直读光谱仪的多通道数据采集与处理系统。基于微弱光电信号的特性和系统性能指标的需求,设计了以FPGA为控制核心、信号调理模块增益可控、多通道数据并行采集、实现数据无损传输的系统总体设计方案。设计了实现数据采集系统各功能模块的硬件电路,以及FPGA对系统各个模块的控制逻辑,并完成系统硬件测试和功能测试。测试结果表明本系统能够采集光电倍增管输出的微弱电流信号。  相似文献   

4.
光电位置传感器(PSD)具有响应时间短、位置分辨率高、光谱响应范围大的优点。本文介绍了 PSD 的标定方法及在光扫描测试技术上的应用,其电路信号处理简单、精度高、对测量光强不敏感。若将 PSD 动态扫描角测试系统的性能更加完善,可形成一种具有实用价值的非接触光学动态测试技术。  相似文献   

5.
针对肿瘤深部的微弱光信号检测问题,设计了一套基于微创光纤探头的内窥式荧光数据采集系统,用于评估光动力疗法治疗肿瘤的疗效。该系统分为光电检测和数据采集两个部分。其中光电检测部分以CR186光电倍增管为核心。数据采集部分基于PCI-6251数据采集卡,以Labview为软件平台,实现数据的实时显示和存储功能。该系统可实时反映肿瘤深部的光强变化,对于在体医疗器械的开发和研究,具有一定的应用价值。  相似文献   

6.
美国瓦里安(Varian)联合企业公司最近研制出一种新系列的光电倍增管产品,其光电阴极由砷化镓组成,直径达188mm。因而,其阴极面积为目前所常见的光电倍增管的九倍。这种新系列光电倍增管型号为VPM-192M,与同种用途的其他光电倍增管相比,它有三倍于后者的光灵敏度和二倍以上的峰值量子灵敏度。从而,它可以取代现有的的玻璃管封装式光电倍增管,可用于分析仪器、天文仪器和辐射测量等仪器中。该器件增益为10~4至10~6,最高可达10~7。脉冲频率范围可从0至30MHz,脉冲上升和下降时间(按10%至90%计算)为10nS或20nS。  相似文献   

7.
提出了一种利用旋光色散进行波长测量的方法。采用高灵敏度的硅光电倍增管(SIPM)探测线偏振光通过旋光物质和无旋光物质时的输出光强随步进电机旋转而发生的变化,由此测出旋光物质的比旋光度,从而根据比旋光度的色散特征方程求出对应光源波长。大量实验证明,该波长测量装置的精度为1nm,标准差为0.06nm,该波长检测方法具有良好的可行性与稳定性,并且该测量装置具有结构简单、易于调节等特点。  相似文献   

8.
光电信号检测与采集电路的性能优劣,直接关系到粉尘浓度测量系统的准确度和精确度。在分析研究了光电检测基本原理和微弱信号检测影响因素的基础上,针对粉尘浓度测量系统中光信号的特点,通过采用差分式测量结构,提高光电探测器供电电源的稳定度,选用低噪声、响应快的运算放大器等措施,设计了一种噪声低、反应快、简单实用的微弱光信号检测电路,成功应用到了某粉尘浓度测量系统上。  相似文献   

9.
针对LED器件光强分布的测试方法,在传统光源配光曲线的测试原理的基础上,阐述了旋转法、多探测器法测试LED光强分布的方法。由于这些方法存在测试时间长、测量准确度低以及定标繁琐的缺陷,进而介绍了一种新型测试方法及装置,即通过CCD光度探测器接收光强度,经过CCD的光电转换功能将光强度信号转换为电信号,再通过成像系统软件便可得到整个半球面空间内壁的光强图。新的测试方法具有测试速度快、精度高、信息量丰富和直观性的显著优点。  相似文献   

10.
提出以Nd:YAG激光器的三倍频355nm波长激光为激发光源,以单个光电倍增管(PMT)为探测器,以水体污染监测为目的的激光诱导荧光系统的研制。采用光电倍增管高速双脉冲门控与单次脉冲触发数据采样相结合新技术,有效减少了户外环境下背景光的影响,提高了系统的测量精确度。试验结果表明,该系统能接收水体表面受激发射的荧光信号,探测到的荧光信号经信号处理后与水体受污染程度有良好的相关性。  相似文献   

11.
眼轴长度与屈光不正、白内障等常见眼科疾病有密切关系,精确测量眼轴长度对眼科疾病的预防及治疗具有重要的意义。为实现眼轴长度安全有效的光学测量,入射光强度不能超过安全限度,同时人眼眼底反射出来的光只有入射光的10-3~10-4。为此基于光学方法的眼轴长度测量的弱光探测,设计了一种基于外差干涉测量的眼轴长度测量系统。测量系统硬件部分采用PIN光电二极管将弱光信号转化成易于处理的弱电信号,同时设计一个低噪声、高性能的弱信号处理电路,并选用Max 10系列的10M25SAE作为主控芯片处理信号;软件部分采用VHDL语言进行编程。实验结果表明,该测量系统可以对眼轴长度实现有效且稳定的测量。  相似文献   

12.
This paper is the second part of a continuing study of straight-channel microchannel plate (MCP)-based x-ray detectors. Such detectors are a useful diagnostic tool for two-dimensional, time-resolved imaging and time-resolved x-ray spectroscopy. To interpret the data from such detectors, it is critical to develop a better understanding of the behavior of MCPs biased with subnanosecond voltage pulses. The subject of this paper is a Monte Carlo computer code that simulates the electron cascade in a MCP channel under an arbitrary pulsed voltage, particularly those pulses with widths comparable to the transit time of the electron cascade in the MCP under DC voltage bias. We use this code to study the gain as a function of time (also called the gate profile or optical gate) for various voltage pulse shapes, including pulses measured along the MCP. In addition, experimental data of MCP behavior in pulsed mode are obtained with a short-pulse UV laser. Comparisons between the simulations and experimental data show excellent agreement for both the gate profile and the peak relative sensitivity along the MCP strips. We report that the dependence of relative gain on peak voltage is larger in pulsed mode when the width of the high-voltage waveform is smaller than the transit time of cascading electrons in the MCP.  相似文献   

13.
本文介绍了用波长为632.8nm的He—Ne激光器作为光源测量透射比小于10-7/cm2的X光滤光片针孔透射比的方法。为了测量这样低的透过率,我们设计和安装了反射式超低透过率测定装置。用黑色玻璃作为反射式衰减元件,用光电倍增管作为接收器,用数字电压表作为读数仪表。同时,还用中性玻璃滤光片组作为透过式衰减器,也测量了超低透过率。两种方法都得出满意的结果。  相似文献   

14.
Dr K. Berndt 《Measurement》1987,5(4):159-166
Correlation analysis has become an important research tool in the investigation of signals and systems behaviour. We report on a special opto-electronic cross-correlator in which a silicon avalanche photodiode is used as the main component. The internal gain of this photodiode is pulse-modulated with 330 ps FWHM at 126 MHz repetition rate, or is modulated sinusoidally at frequencies of up to 882 MHz, respectively. In the pulsed mode, very weak repetitive optical pulses can be detected with 3 × 10−3 photons per pulse sensitivity, and with 10 ps timing accuracy. The second mode offers time-selective signal rejection capabilities with 3 ps time resolution. The opto-electronic cross-correlator can be used in displacement and distance measurement, robotics, time dispersion analysis in optical fibres, transient absorption spectroscopy, fluorescence decay measurement, lifetime-selective fluorescence detection, and in fluorescence signal suppression in Raman spectroscopy.  相似文献   

15.
二维计数跟踪型激光多普勒测速系统利用两个计数跟踪光电混合反馈环路来分离并测量速度的二维分量。通过智能控制,寻找适当的初始光学频移档次,使得光电信号的有效频率成分分别进入各自对应的信号处理器处理带宽内,同时监视LDA的工作状态,对采集得到的两个环路的光电信号频率及相应的光学频移量,进行一系列的信号处理工作,最终可获得测量点的二维速度分量。二维智能计数跟踪型LDA在非对称突扩管道的流场测量中的应用结果,证实了该套系统的研制是成功的。  相似文献   

16.
Recently developed transducers utilise the unique characteristics of Deformed Helix Ferroelectric Liquid Crystal (DHFLC) to linearly and passively transduce small voltage signals into the optical domain. These small optical transducers can be retrofitted to an existing flowmeter network where the true benefits of distributed sensing in the optical domain can be leveraged. Signals from multiple sensors can be multiplexed into a single optical fibre for measurement at a remote location. We demonstrate two methods of signal measurement based on a positive displacement oval gear flowmeter. Utilising a reed switch to produce short pulses, errorless flow rate transduction is possible across all flow rates including very low flows. Using a variable reluctance sensor, completely passive transduction of flow rates can be achieved. The same technique can be applied to any sensing network with an electrical signal output.  相似文献   

17.
A high-voltage transistor voltage divider for photomultiplier tubes consists of a high-resistance linear resistive divider specifying potential distributions between dynodes and emitter followers maintaining this distribution. The divider features a low dissipation power and stable gain of the photomultiplier tube, when the average anode current varies in the entire measurement range.  相似文献   

18.
Partial discharge (PD) measurement is a promising method for condition assessment of insulation systems in high voltage equipments. Conventional PD measuring systems have some difficulties in the measurements especially in online conditions and noisy environments. There is a growing tendency to use new measuring systems for separation of PD pulses from different sources and rejection of external noises. In this investigation a new ultra wideband PD measuring system and relevant methodology are discussed. The proposed system uses an efficient detection method for extracting PD pulses embedded in noisy signal, meanwhile, a wavelet multiresolution analysis is applied to reduce background and communication noise level. In this paper some new and modified features for pulse classification procedure have been proposed. The proposed system, methodology and features have been implemented on a hydrogenerator and also a power transformer. Finally performance of the system is discussed.  相似文献   

19.
为了实现电磁干扰环境下的心电信号监测,提出了一种抗电磁干扰的心电信号监测系统。论文给出了输出光电流的计算公式,分析了半波电压及插入损耗对系统灵敏度的影响。利用铌酸锂电光晶体搭建实验系统,测试了5位健康志愿者的心电信号。应用提出的系统和电学心电信号采集系统分别测试了正常环境及电磁环境下志愿者的心电信号。测试结果表明:在正常环境下,本系统能获得与电学心电信号采集系统同样清晰的心电信号波形;在电磁环境下,本系统获得的心电信号优于电学心电信号采集系统。最后定量计算了两者的信噪比,计算结果表明:在电磁干扰下,本系统的信噪比变化量为0.54dB(V2)/0.49dB(V4),而电学心电信号采集系统的信噪比变化量为24.07dB(V2)/16.75dB(V4)。  相似文献   

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