桑色素-Al掺杂的溶胶-凝胶薄膜修饰的MPOF光纤氟离子传感探头

本文通过对微结构聚合物光纤修饰桑色素-铝配合物掺杂的凝胶薄膜,制备了一种氟化物光纤传感探头。这种探头的结构基于微结构聚合物光纤实现,其内部具有贯穿的微孔道结构,这种微孔结构可以作为敏感材料的载体以及微传感池。敏感层的修饰通过溶胶-凝胶过程实现,将掺有桑色素-铝的溶胶直接吸入光纤内部,可以在光纤微孔阵列中形成凝胶敏感膜。微结构光纤内部可以容纳微量液体,传感过程在微孔道内进行。传感原理基于荧光淬灭远离实现,氟离子对凝胶膜中桑色素-铝具有强烈的荧光淬灭作用,因此传感探头对于不同浓度的氟离子溶液表现不同的荧光强度。在pH值为4.6的条件下,探头对于氟离子具有良好的响应,其传感范围为5-50mmol/L。     

光纤O2敏感探头的制备与性能测试

通过对多孔光纤修饰Ru配合物掺杂的敏感膜,制备了一种O2光纤传感探头。该探头结构基于简单的多孔光纤,内部设有贯穿的微孔道作为敏感材料的载体以及微传感池,在微孔道内完成传感过程。通过沉积凝胶膜修饰敏感层,即将含有[Ru(dpp)3]2+的溶胶直接吸入光纤内部,在光纤微孔阵列中形成高分子敏感膜。传感过程基于荧光淬灭原理,由于O2对敏感膜中的[Ru(dpp)3]2+具有强烈的荧光淬灭作用,传感探头对于不同浓度的O2表现不同的荧光强度。实验结果表明:设计的探头对于0～100%浓度的O2呈线性响应,灵敏度I0/I100值为9.4,探头在50ms内即可做出快速响应。实验还显示,实验值与真值的误差小于3%,常压下的检测分辨率可以达到2%。     

电纺氧化硅凝胶亚微米光波导

利用静电纺丝技术制备了有机硅微纳凝胶光纤.在酸性条件下对正硅酸乙酯(TEOS)和正辛基三乙氧基硅烷(Octyl-triEOS)进行水解缩聚,同时掺杂氧气敏感荧光指示剂tris(4,7-diphenyl-1,10-phenanthroline) ruthenium( Ⅱ) chloride[Ru(dpp)3Cl2],反应形成黏稠的溶胶溶液.然后,在10 kV高压静电场作用下对溶胶进行静电纺丝,获得直径为900 nm的凝胶纤维,并对拉锥后的多模光纤与电纺制备的微纳光波导纤维进行倏逝场光耦合,同时检测该纤维的氧气传感特性.实验结果表明:电纺制备的纤维具有光滑的表面结构,直径均匀,能够与拉锥后的光纤进行强烈的倏逝场耦合,同时激发纤维内部荧光指示剂,发射595 nm荧光.该纤维具有明显的氧气敏感性,在氧气浓度为0％～100％(体积比)时,荧光淬灭程度I0/I与氧气浓度呈线性关系,响应时间低于100 ms.     

基于强度法和相移法的光纤氧传感测量系统

利用荧光猝灭原理检测氧浓度,构建了在线测量系统,可同时实现强度法测量和相移法测量。优选邻三(4,7-联苯-1,10-邻菲啰啉)二氯化钌为荧光指示剂,采用溶胶-凝胶法制备氧敏感膜,组装光纤氧传感探头。结果表明,氧浓度在0~100%范围内,荧光强度与氧浓度呈线性关系(R20.99);系统参数对相移法测量的影响明显,通过参数调控可进行系统优化实现低氧浓度的高精度检测,理论检测下限约为3 ppm。     

基于荧光猝灭的锥尖型光纤氧传感探头

利用动态化学腐蚀法制备锥尖型光纤端面,以提拉法镀溶胶凝胶敏感膜,组装了基于荧光猝灭的直径仅1.5 mm的光纤氧传感探头。探头锥面的长径比可通过调控腐蚀参数(温度、腐蚀液面下降速度)调控。构建相移测量系统,优化参数后进行0~21%范围内的氧含量测定,工作曲线呈现良好的线性特征(R2=0.999 6),偏差小于测量值的5%。     

水中油浓度的光纤荧光在线测量系统

介绍能够实现水中油浓度在线测量的光纤荧光测量系统.系统以荧光现象的选择性和鉴别性为理论基础、将光纤传感和计算机数据处理技术相结合,具有结构简单、探头无源的特点.实验结果表明该测量方法是完全可行的.     

马赫-曾德尔干涉集成化的全光纤磁场与温度传感器

为了简化光纤磁场与温度传感器的结构并提高传感器灵敏度,设计并制作了马赫-曾德尔干涉集成化的全光纤磁场与温度传感器。将单根光纤的马赫-曾德尔模间干涉结构和双臂马赫-曾德尔干涉结构结合:将总长度为1.2m的单模光纤部分制备成长度为2.7cm、锥腰直径为30.1μm的锥形微纳光纤,并得到了拉锥时间与锥腰直径的关系。将锥形微纳光纤放置尼龙槽内并包覆磁凝胶构成传感头,实现模间干涉的马赫-曾德尔磁场传感器;将磁场传感器通过两耦合比为50%∶50%的耦合器并联带有可调谐光衰减器的单模光纤形成马赫-曾德尔干涉的温度传感器。从理论上分析了光谱漂移对磁场和温度传感的特性关系,实验测得室温下磁场强度在25~50mT时,磁场传感的灵敏度为0.301 14nm/mT;在磁场强度为0,温度由25℃升高到30℃时,温度传感的灵敏度为0.518 86nm/℃。该传感器可广泛应用于电力系统放电检测、材料加工、安全监控等领域。     

基于水凝胶聚合物波导传感器检测盐酸吖啶黄

多功能化是光纤化学传感器的重要发展方向。为实现该目标,首先通过激光诱导波导自形成技术制备了一种光纤–水凝胶聚合物波导–光纤传感结构,并在水凝胶聚合物波导探针中成功地掺杂了纳米金颗粒。在该结构中,波导与光纤同轴无缝相连,保证了探测光和信号光的高效利用。掺金后的聚合物波导具有丰富的光谱探测能力,利用该波导探针成功实现了对盐酸吖啶黄的吸收、荧光以及拉曼光谱的检测,扩大了波导传感器的应用范围。     

基于纳米修饰透射式光纤传感测试

基于金属纳米颗粒结构的光学特性,结合光纤传感技术,对金属纳米颗粒的光纤传感特性进行了研究.实验中采用种子溶液生长法合成了粒径在60～80 nm的星形纳米金颗粒,以此作为光纤传感敏感部分的修饰体,修饰到锥形光纤表面作为表面拉曼增强基底.最后选取了不同浓度的酒精溶液对其进行了透射谱和拉曼谱测试,结果表明金属纳米颗粒的激发谱对周围介质特性非常敏感,同时对基于金属纳米颗粒锥形SERS基底的拉曼谱存在非常高的增强.     

玻璃封装医用小型光纤光栅温度传感探头

针对体内测温、特别是肿瘤热疗体内温度实时监测对温度传感探头的体积、韧性和抗电磁干扰能力的要求,对医用小型光纤光栅温度传感探头进行了研究。提出了利用玻璃管封装短光纤布拉格光栅来有效避免应力引起的误差以及金属封装对电磁场分布的影响,同时提出用医用聚氨酯套管包裹探头及光纤来有效地保护探头及光纤并使其具备很好的韧性。封装后,探头截面直径为1mm、长度约为4mm。实验测量了稳定温度源在不同温度下探头的反射波长响应和温度变化时探头的响应时间,并测量了医用热疗机加热猪肉时肉内部的温度变化过程。结果表明,体温范围内探头反射波长与温度的线性相关系数可达0.999 95,温度传感精度为0.2℃,探头最大响应时间约为4s,并能实时监测医用热疗机加热猪肉时其内部的温度变化。     

悬臂式光纤探针

悬臂式探针的研制是 SNOM- AFM的重要技术之一。用熔拉—腐蚀相结合的方法 ,将普通单模石英光纤制成直锥型探针。再利用自制的工具在 CO2 激光束下将针尖打弯 ,制成悬臂式探针样品。简单地讨论了此种探针的弹性常数     

Graphene-based optical fiber ammonia gas sensor

To precisely monitor and forecast harmful gases in the air, a high-performance fiber gas sensor based on graphene nanometer-functional materials is proposed and experimentally demonstrated. The sensing area of the proposed sensor was a graphene-wrapped fiber which was cascaded between a down-taper and an up-taper. The graphene wrapping on the subuliform fiber sensing area substantially increased the evanescent field which transmits along the surface of fiber and will have a significant sensitization effect on the gas sensing. At the same time, the gas molecules adsorbed by graphene lead to changes of the effective refractive index of the composite waveguide, which causes corresponding wavelength drift and attenuation. By detecting the change of the output optical signal, the concentration of gas molecules was detected. Based on this principle, the sensor realized a gas sensitivity of 0.015?nm/ppm. The research shows that the sensing structure has the advantages of small volume, good mechanical strength, excellent spectral quality, and high sensitivity.     

Influence of Mg doping on the morphology and optical properties of ZnO films for enhanced H2 sensing

Highly oriented ZnO and Mg doped ZnO thin films were fabricated on Al₂O₃ substrate by sputtering at room temperature. The effect of Mg doping on the structural, optical, and morphological properties of ZnO film was investigated. The intensity of (002) peak in X‐ray diffraction measurements revealed the influence of Mg doping on the crystallinity and orientation of ZnO film. Photoluminescence (PL) results show that the Ultraviolet (UV) emission peak was shifted to lower wavelength side for Mg:ZnO film indicating the possibility for quantum confinement. UV–vis–NIR optical absorption revealed an improvement in optical transmittance from 70 to 85%, and corresponding optical band gap from 3.25 to 3.54 eV. Atomic force microscope (AFM) images revealed the nano‐size particulate microstructure of the films. The surface topography of Mg doped ZnO film confirmed decreased grain size with large surface roughness and increased surface area, favorable for sensing. Pure ZnO and Mg doped ZnO film were used as active layer and tested for its sensing performance to hydrogen. Compared to undoped ZnO, 22 at.% Mg doped ZnO film showed much higher sensor response to H₂ at a concentration as low as 200 ppm and at a lower operating temperature of 180°C. A linear sensor response was observed for H₂ concentration in the range of 100–500 ppm. Microsc. Res. Tech. 76:1118–1124, 2013. © 2013 Wiley Periodicals, Inc.     

可在轨溯源的太阳反射波段光学遥感仪器辐射定标基准传递链路

分析了现行光学遥感仪器辐射定标方法的局限性,以满足定量化遥感的精度及多数据融合比对研究的需求。设计了以空间低温辐射计为初级辐射基准,以太阳为光源,包括太阳单色仪、太阳光谱仪、传递辐射计、太阳漫反射板等组件在内的可在轨溯源的光学遥感仪器辐射定标基准传递链路。首先以低温辐射计和太阳光源建立的光谱辐射基准定标传递辐射计和太阳光谱仪;然后利用传递辐射计定标太阳漫反射板,建立对地光谱辐亮度基准;继而将基准传递至地球光谱成像仪作为对地观测标准,从而实现对其它卫星光学遥感器的交叉定标。对光学遥感仪器辐射定标基准传递链路各个环节的分析显示,辐射定标基准传递链路的测量相对不确定度为0.75%。结果表明,以此辐射基准传递链路构建覆盖我国空天一体的遥感定标网络可为建立平行于地面基准体系的空间数据质量保障体系奠定技术基础。     

Current-sensing scanning near-field optical microscopy using a metal probe for nanometre-scale observation of electrochromic films

A novel technique for scanning near‐field optical microscopy capable of point‐contact current‐sensing was developed in order to investigate the nanometre‐scale optical and electrical properties of electrochromic materials. An apertureless bent‐metal probe was fabricated in order to detect optical and current signals at a local point on the electrochromic films. The near‐field optical properties could be observed using the local field enhancement effect generated at the edge of the metal probe under p‐polarized laser illumination. With regard to electrical properties, current signal could be detected with the metal probe connected to a high‐sensitive current amplifier. Using the current‐sensing scanning near‐field optical microscopy, the surface topography, optical and current images of coloured WO₃ thin films were observed simultaneously. Furthermore, nanometre‐scale electrochromic modification of local bleaching could be performed using the current‐sensing scanning near‐field optical microscopy. The current‐sensing scanning near‐field optical microscopy has potential use in various fields of nanometre‐scale optoelectronics.     

Computational analysis of responses of a wedge-shaped-tip optical fiber probe in bubble measurement

Optical-fiber probing is widely employed in bubble∕droplet measurement in gas-liquid two-phase flows. Several types of optical fiber probes with a very high S∕N ratio and high performance have been developed, but further improvement in the probes' measurement accuracy and reliability for industrial applications is desired. We tried to eliminate optical noise in the probe measurements, and we found that the signals include some peak signs that have potential for advanced measurement with optical-fiber probing. We developed a ray-tracing numerical simulator and identified the mechanisms underlying the generation of the signals. In order to numerically simulate the optical probing signals, the simulator must use 3D frameworks composed of incident beams, the reflection and refraction on the surfaces of the optical elements (i.e., an optical fiber, a sensing tip, an air phase, and a water phase), and beams returning from the sensing tip to the other tip through the fiber. We used all of these in a simple rendering framework based on a ray-tracing algorithm with Fresnel's law, and we observed the mechanism of some promising signals that may be useful for extracting the hidden potential of optical-fiber probing. To verify the simulator's performance, we carried out three comparative experiments with fundamental setups using a wedge-shaped single-tip optical fiber probe, examining: (1) the beam trajectories and energy leaking out from the sensing tip into the surrounding air phase or water phase, (2) the probing signals throughout penetration of the sensing tip at the air-water free interface in light of the three-dimensional deformation, and (3) the probing signals throughout penetration of the sensing tip into a bubble in light of the three-dimensional bubble shape. As a result, (a) we found that an optical fiber probe with a wedge-shaped tip has particular characteristics of beam emissions from the tip, and the emitting angles switched depending on the phases covering the tip. This phenomenon is very effective for further advanced measurement. (b) We observed numerically that the cutting angle of the sensing tip maximizing the air signal level was approximately 30°, and therefore this angle is the best for obtaining the highest S∕N ratio. (c) We found that the meniscus shape clearly affected the probing signal optically. (d) We observed the mechanism of a pre-signal caused by the reflection at the frontal and rear interfaces of a bubble. The pre-signal is very useful for practical measurement because it appears only when the probe penetrates the center region of a bubble. We compared the above numerical results with the results of the three experiments, and there was satisfactory correspondence between the numerical and experimental results.     

光学遥感卫星信息获取能力指数的评估

提出了一种客观评估遥感卫星获取信息能力的指数模型。分析了影响遥感卫星信息获取能力的主要因素,包括运行轨道、成像分辨率、成像幅面、姿态机动能力等。以目标综合辨识量作为衡量标准,建立了涵盖成像分辨率、目标重访、姿态机动能力等要素的信息获取能力指数评价模型。介绍了模型的实现流程和具体步骤。该模型集成目标获取数量和目标获取精度两个维度信息,可实现遥感卫星信息获取能力的综合评估。以世界观测(Worldview)卫星系列、昴星团(Pleiades)和高景一号(Superview-1)等国内外光学遥感卫星为例进行了验证分析。结果表明,该指数模型能够对性能各异遥感卫星的信息获取能力做出准确评估,如WorldView-3的分辨率不到WorldView-1的分辨率的两倍,但信息获取能力却是其是3倍多;Superview-1分辨率比Pleiades高,但实际信息获取能力还不到后者的一半。得到的结果验证了提出模型的有效性,表明提出的模型可为综合评价光学遥感卫星遥感能力提供量化参考,为光学遥感手段的发展提供评估模型支持。