Optoelectronic oscillator-based interrogation system for Michelson interferometric sensors

High-performance interrogation systems for optical fiber sensors are extensively required for environmental condition monitoring applications.In this article,we propose and demonstrate a Michelson interferometer(MI)interrogation system based on an optoelectronic oscillator(OEO).The frequency of the OEO is related to the free spectral range(FSR)of the MI.Thus,when the FSR of the MI varies with a change in external physical factors,the frequency of the OEO shifts and can be used for interrogation.We demonstrate that the temperature sensitivity and interrogation resolution are 35.35 MHz/℃and 0.012℃,respectively.Such an OEO-based scheme enables wavelength-to-frequency mapping and promises a wide linear interrogation range,high resolution and high-speed interrogation.

Nanocrystalline CuO Thin Films for H₂S Monitoring: Microstructural and Optoelectronic Characterization

Nanocrystalline copper oxide (CuO) thin films were deposited onto glass substrates by a spin coating technique using an aqueous solution of copper acetate. These films were characterized for their structural, mor-phological, optoelectronic properties by means of X-ray diffraction (XRD) scanning electron microscopy (SEM), UVspectroscopy and four probe method. The CuO films are oriented along (1 1 1) plane with the monoclinic crystal structure. These films were utilized in H2S sensors. The dependence of the H2S response on the operating temperature, H2S concentration of CuO film (annealed at 700。C) was investigated. The CuO film showed selectivity for H2S. The maximum H2S response of 25.2 % for the CuO film at gas concentra-tion of 100 ppm at operating temperature 200oC was achieved.

采用AD654芯片的直流电压传感器及其温度漂移补偿

提出一种基于电压-频率变换的光电式电压传感器及电压传感信号温度漂移的补偿方法。电压传感系统主要包括电阻分压器、电压-频率变换芯片、发光二极管、光纤、光电探测与信号处理单元等。利用两块AD654型芯片分别作为被测电压和温度传感单元,通过对两路光传感信号进行非线性数据拟合等方式实现了对电压传感信号温度漂移的实时补偿。实验测量了0.6 kV~5.0 kV范围内的直流电压,并实现了电压传感信号的温度漂移补偿,在-40℃~+60℃的温度范围内,电压传感信号温度漂移的平均相对误差约为±0.7%。

基于STM32分时采样的颜色传感器的设计

机器人的应用离不开传感器,传感器应用成为青少年教育中机器人的一个重要技术。如在循线机器人中,光电传感器能够识别地面的白色和黑色,以实现机器人沿着黑线前进的目的。最近几年随着科技的发展,颜色识别的应用场景越来越多,如解魔方机器人、追球机器人等就需要颜色的识别。用传统的光电传感器不能准确地识别彩色;而用摄像头识别技术又显得大材小用,同时青少年在技术上也不能灵活地驾驭。从能否用传统的光电技术设计一个颜色识别传感器的角度出发,利用物理光学知识和新兴的单片机技术,研究并设计了一款灵敏度高、可靠性强且体积小的颜色识别传感器。

Low-dimensional optoelectronic synaptic devices for neuromorphic vision sensors

Neuromorphic systems represent a promising avenue for the development of the next generation of artificial intelligence hardware.Machine vision,one of the cores in artificial intelligence,requires system-level support with low power consumption,low latency,and parallel computing.Neuromorphic vision sensors provide an efficient solution for machine vision by simulating the structure and function of the biological retina.Optoelectronic synapses,which use light as the main means to achieve the dual functions of photosensitivity and synapse,are the basic units of the neuromorphic vision sensor.Therefore,it is necessary to develop various optoelectronic synaptic devices to expand the application scenarios of neuromorphic vision systems.This review compares the structure and function for both biological and artificial retina systems,and introduces various optoelectronic synaptic devices based on low-dimensional materials and working mechanisms.In addition,advanced applications of optoelectronic synapses as neuromorphic vision sensors are comprehensively summarized.Finally,the challenges and prospects in this field are briefly discussed.

Progress of Materials and Devices for Neuromorphic Vision Sensors

The latest developments in bio-inspired neuromorphic vision sensors can be summarized in 3 keywords:smaller,faster,and smarter.(1)Smaller:Devices are becoming more compact by integrating previously separated components such as sensors,memory,and processing units.As a prime example,the transition from traditional sensory vision computing to in-sensor vision computing has shown clear benefits,such as simpler circuitry,lower power consumption,and less data redundancy.(2)Swifter:Owing to the nature of physics,smaller and more integrated devices can detect,process,and react to input more quickly.In addition,the methods for sensing and processing optical information using various materials(such as oxide semiconductors)are evolving.(3)Smarter:Owing to these two main research directions,we can expect advanced applications such as adaptive vision sensors,collision sensors,and nociceptive sensors.This review mainly focuses on the recent progress,working mechanisms,image pre-processing techniques,and advanced features of two types of neuromorphic vision sensors based on near-sensor and in-sensor vision computing methodologies.

Pressure Sensor of Fiber Optics Coupling Type

The principle of fiber optics coupling pressure sensor with micro-power dissipation is introduced as well as the use of two-way signal single fiber transfer(measure signal and reference signal)to conduct a proportional measure.It also discusses the adopted ways for improving the stability temperature drift and the noise of the measuring system.

太赫兹平面环偶极子超材料传感器及地沟油检测

利用镜像对称的方形双开口环结构设计制备了一款太赫兹环偶极子超材料传感器,该传感器在1.436 THz处产生Q值为16.8的透射谐振谷。谐振频率处结构表面电流分析表明,该结构能在抑制电偶极子和磁偶极子的同时迅速增强环偶极子。作为生物传感器,该器件在分析物厚度饱和时灵敏度高达348.8 GHz/RIU,可以高灵敏感测表面介电环境的微小变化。实验结果验证了其对标准食用油和劣质地沟油的良好分辨性,表明该器件在食品安全监测等方面有着潜在的应用前景。

绿光收发一体式集成光电子芯片的脉搏检测传感器

光学体积描记(PPG,photo plethysmo graphy)因其设计简单、成本低、信号周期能有效反应心脏节律等特点被广泛应用于检测心率及脉搏活动。基于多量子阱(MQW,multiple quantum well)二极管发光谱与探测谱存在重叠区的物理现象,采用兼容工艺在一块氮化镓芯片上实现光发射和接收器件的集成,研制收发一体式集成光电子芯片及脉搏传感器。实验结果表明,该氮化镓集成光电子芯片能够有效地接收经过心脏脉冲调制过的反射光。结合电路处理,能够根据还原的PPG信号计算出测试者的心率及脉搏跳变频率,以此起到检测和警示的作用。

One Dimensional Nanostructures for Lithium-ion Batteries, Gas Sensors and Optoelectronics Applications

1 Results One dimensional (1D) nanostructures such as nanowires,nanotubes,nanorods and nanoribbons have been extensively investigated for a wide range of applications[1].Here,we present the synthesis,characterization and technological applications of several 1D nanostructures including SnO2 nanowires,CuO nanoribbons,CdSe nanowires and In2O3 nanowires.SnO2 nanowires were synthesized by thermal evaporation combined with a self-catalyzed growth procedure.Scanning electron microscopy (SEM) observation shows...

Atmospheric corrosion mapping of copper surfaces from diffuse light scattering measurements by an optoelectronic sensor system

A novel light scattering technique for mapping metal surface corrosion is presented and its results on copper exposed to atmosphere are reported. The front end of the instrument is made up of a sensor module comprising a thin beam light emitting diode (LED) illuminating a small spot on the metal surface, and a matched pair of photodetectors, one for capturing the reflected light and the other for sampling the scattered light. The analog photocurrent signals are digitized and processed online by a personal computer (PC) to determine the corrosion factor defined in terms of the two current values. By scanning the sample surface using the light beam and by computing the corrosion factor values simultaneously, a three dimensional graph and a two dimensional contour map are generated in the PC using Matlab tools. The values of the corrosion factor measured in different durations of exposure to atmosphere, which obey a bilogarithmic law, testify to the validity of our mathematical model.

基于中红外光谱吸收技术的一氧化碳气体检测系统

基于中红外光谱吸收技术,利用一氧化碳(CO)气体分子在4.6μm处的基频吸收带,采用新脉冲的红外光源和双通道的热释电探测器,研制了一种CO浓度检测系统。该系统主要由脉冲调制式宽带热光源、开放式椭球聚光镜/气室、双通道探测器、主控及信号处理模块构成。通过优化开放式椭球聚光镜/气室,气体吸收光程达到40cm,探测器输出电信号的幅度增加约为原来的2~3倍。因此,采用椭球聚光镜后,将在一定程度上提高系统的信噪比从而改善系统的性能指标。利用配备的CO气体样品,研究了该系统对CO气体的传感特性。实验结果显示,该系统的最小检测下限为10ppm,在该浓度点的测量误差约为14%;在20~25 000ppm范围内的测量误差小于7.8%;对0ppm气体样品的连续50分钟测量结果的最大偏差约为3ppm,标准差约为0.18ppm。同基于量子级联激光器和分布反馈激光器的CO检测系统相比,该系统具有性价比高、光路结构简单等优势,从而在煤矿、环保等场合下的CO检测方面具有较好应用前景。

表面等离子体共振传感器研究的新进展

表面等离子体共振传感器具有灵敏度高、免标记及检测快速等优点,在生命科学、药物开发、公共安全、环境污染检测等领域具有广阔的应用前景。高灵敏度、小型化、集成化、低成本、高可靠性是未来表面等离子共振传感器发展的主要方向。介绍了棱镜耦合复合结构表面等离子体共振传感器在提高灵敏度和分辨率方面的研究新进展,重点论述了光纤表面等离子体共振传感器的研究现状和发展趋势,并对高通量、多组分识别表面等离子体成像技术以及金属微纳结构(颗粒)局域表面等离子共振传感技术的应用前景进行了讨论。

一种永磁球形步进电机转子位置的检测方法

介绍了永磁球形步进电机模型,在转子球面上按随机编码规则确定黑、白两种颜色,采用光电传感器对颜色进行识别,光电传感器的输出用来表示转子的位置。在随机编码规则下,对位置识别的分辨率进行研究,并建立产生式系统对光电传感器采集的信号进行检测,推理出当前转子所处的空间位置,求解的过程归结为对状态空间的搜索。对大空间问题,搜索策略是要解决组合爆炸的问题,建立评价函数进行启发式搜索,仿真表明该方法大大缩小了搜索范围,节省了搜索时间。

光电液位传感器及其在桥梁挠度自动测量中的应用

挠度是反映桥梁线性变化的重要参数,光电液位传感器是一种新型的连通管液位检测传感器,它的测量精度能达到0.1mm。将光电液位传感器、连通管、485总线、RS485/232转换卡、计算机等组成桥梁挠度自动测量系统,能够对大型桥梁挠度进行多点、长期、在线、远程、自动监测且不受桥梁现场高尘、高湿和浓雾的影响。目前,该系统已经成功应用到重庆大佛寺长江大桥上,测量结果表明可以准确获取桥梁的挠度信息,测量的挠度值能够真实反映桥梁的挠度变化,是一种有效的桥梁挠度自动测量方法。

基于光电传感器的精密排种器性能检测

研究设计了由发红外光二极管、凸透镜、PD-0120A型硅光电池裸片组组成的无盲区检测精密排种器性能的传感器以及以89C51型单片机为核心控制部件的硬件系统和软件系统。通过传感器检测、人工检测对比试验证明了该无盲区传感器可准确地检测精密排种器的各项性能指标。

差分式中红外一氧化碳检测仪的研制

根据CO分子在中红外波段的吸收特性,利用红外热辐射光源(IR55)和双通道热释电探测器(LM244),研制了一种差分式CO检测仪。通过双通道锁相放大器对探测器输出的两路信号进行处理,有效地抑制了系统噪声,提高了仪器的检测精度。介绍了系统的检测原理,给出了光学系统和双通道锁相放大器的实现方案,该锁相放大器能提取的最小标准信号幅度为1 m V,移相误差小于0.2%。利用配备的体积分数为0~1×10^(-3)的CO样品,开展了气体检测实验。实验结果表明:系统的检测下限为1×10^(-5),相对测量误差小于15%。当气体体积分数为0×10^(-6)时,测得浓度的波动范围为-5.2×10^(-6)~6.2×10^(-6)。考虑静态配气时气体在气室中扩散的时间,仪器的响应时间约为58~62 s。同基于量子级联激光器和分布反馈激光器的CO检测仪相比,所研制的仪器具有结构简单、性价比高等优势,在煤矿、环保等场合的CO检测方面具有较好的应用前景。

基于光纤光栅振动传感器的桥梁索力实时监测

将研制成功的光纤光栅振动传感器以及桥梁索力实时监测系统应用于武汉长江二桥进行索力长期远程实时监测.光纤光栅振动传感器输出的信号可在光纤中进行远程传输,能在任何气候条件下长期稳定工作,适合于桥梁拉索索力的长期远程实时监测;开发的桥梁索力实时监测系统软件,具有拉索特征频率自动识别能力,可以实时进行索力计算.通过对武汉长江二桥拉索索力的实时监测,得到了桥梁索力的分布及其运行状况,为桥梁安全评估提供了可靠的依据.该系统可推广应用于其他大型斜拉索桥.

基于一次电光效应的非接触式过电压监测传感器

高压电网中过电压的测量对于研究过电压的行为特征和绝缘配合设计具有重要的意义。为了实现高压电网的安全准确测量,采用具有良好一次电光效应特性的铌酸锂晶体设计了无源集成的光电电压传感单元以及使用该单元的非接触式过电压监测传感器。传感器的分压单元由单元自身电容和定值电容并联构成的低压臂电容与高压导线和感应金属板的耦合电容串联构成。光电电压传感单元全光纤连接,只需感应从分压单元引出的较低幅值电压信号,且无需在传感器安装点提供电源。对设计的传感器的各项测试表明:该传感器不仅具有良好的线性工作区,同时在雷电和操作冲击电压下其高频响应精度较高(幅值反算误差<3%,响应时间误差<0.1μs),适用于各电压等级的过电压非接触无源监测。

用于地沟油快速检测的光纤传感器

基于侧边抛磨光纤倏逝波原理,研制出的地沟油和食用植物油快速检验和测定的光纤传感器。该传感器是在光源稳定的情况下,用地沟油和食用植物油分别完全覆盖侧边抛磨光纤抛磨区,用光功率计测量侧边抛磨光纤出射光功率。实验表明,在常温下(25℃),将地沟油和食用植物油分别完全覆盖抛磨区,造成的输出光功率衰减值相差5～20 dB,可以有效的检验出地沟油。这种新的传感器具有可携带、分辨率较高、响应迅速、检测时间短、成本低廉等优点,易于推广和应用。