Temperature Field in Laser Line Scanning Thermography: Analytical Calculation and Experiment

The temperature field in laser line scanning thermography is investigated comprehensively in this work,including analytical calculation and experiment.Firstly,the principle of laser line scanning thermography is analyzed.On this basis,a physical laser line scanning model is proposed.Afterwards,based on Fourier transform(FT)and segregation variablemethod(SVM),the heat conduction differential equation in laser line scanning thermography is derived in detail.The temperature field of the composite-based coatings model with defects is simulated numerically.The results show that the laser line scanning thermography can effectively detect the defects in the model.The correctness of the analytical calculation is verified by comparing the surface temperature distribution obtained by analytical calculation and numerical simulation.Additionally,an experiment is carried out and the changeable surface temperature obtained by analytical calculation is compared with the experimental results.It shows that the error of maximum temperature obtained by analytical calculation and by experiment is 8%with high accuracy,which proves the correctness of analytical calculation and enriches the theoretical foundation of laser line scanning thermography.

RESEARCH ON A SCANNING NEAR-FIELD MICROSCOPY BASED ON A QUARTZ RESONATOR

A scanning near field acoustic microscopy(SNAM) used in imaging the topography of precise surfaces is presented. As a micro force sensor, a non encapsulated 1 MHz quartz resonator is damped by hydrodynamic forces when approaching an object. Thus the oscillating characteristics of the leg of the quartz resonator change. While measuring the decrease of the amplitude of vibrating, the shape of the object can be obtained. Based on the analyses of the principle and key parameters of SNAM, a SNAM is exploited. A lateral resolution of 0.5 μm and vertical resolution of 2 nm has been achieved in the experiments.

A novel phase-sensitive scanning near-field optical microscope

Phase is one of the most important parameters of electromagnetic waves. It is the phase distribution that determines the propagation, reflection, refraction, focusing, divergence, and coupling features of light, and further affects the intensity distribution. In recent years, the designs of surface plasmon polariton （SPP） devices have mostly been based on the phase modulation and manipulation. Here we demonstrate a phase sensitive multi-parameter heterodyne scanning near-field opti- cal microscope （SNOM） with an aperture probe in the visible range, with which the near field optical phase and amplitude distributions can be simultaneously obtained. A novel architecture combining a spatial optical path and a fiber optical path is employed for stability and flexibility. Two kinds of typical nano-photonic devices are tested with the system. With the phase-sensitive SNOM, the phase and amplitude distributions of any nano-optical field and localized field generated with any SPP nano-structures and irregular phase modulation surfaces can be investigated. The phase distribution and the interference pattern will help us to gain a better understanding of how light interacts with SPP structures and how SPP waves generate, localize, convert, and propagate on an SPP surface. This will be a significant guidance on SPP nano-structure design and optimization.

Particle Velocity Sensor and Its Application in Near-Field Noise Scanning Measurement

The Particle Velocity Sensor (PVS) is a kind of acoustic transducer which measures the particle velocity directly with figure-of-eight directivity. This paper proposes a near-field noise scanning technology based on the research of PVS, pressure-particle velocity (P-U) probe, and its application in noise source identification. Firstly, the principle and characteristics of PVS are presented. Secondly, a P-U probe is designed on the basis of PVS development. Finally, the noise measurement experiment for a single source is arranged and conducted. The result shows that the proposed P-U probe performs well in near-field noise source identification and localization.

Far-Field Pattern Reconstruction from Positioning Errors Affected Near-Field Data Acquired via Helicoidal Scanning

In this paper, an effective technique to compensate the positioning errors in a near-field—far-field (NF-FF) transformation with helicoidal scanning for elongated antennas is presented and validated both numerically and experimentally. It relies on a nonredundant sampling representation of the voltage measured by the probe, obtained by considering the antenna as enclosed in a cylinder ended in two half-spheres. An iterative scheme is used to reconstruct the helicoidal NF data at the points fixed by the representation from the acquired irregularly spaced ones. Once the helicoidal data have been retrieved, those needed by a classical NF-FF transformation with cylindrical scanning are efficiently evaluated by using an optimal sampling interpolation algorithm. Some numerical tests, assessing the accuracy of the approach and its stability with respect to random errors affecting the data, are reported. Experimental tests performed at the Antenna Characterization Lab of the University of Salerno further confirm the validity of the proposed technique.

Standing-wave spectrometry in silicon nano-waveguides using reflection-based near-field scanning optical microscopy

Utilizing reflection-based near-field scanning optical microscopy(NSOM) to image and analyze standing-wave patterns, we present a characterization technique potentially suitable for complex photonic integrated circuits. By raster scanning along the axis of a straight nano-waveguide in tapping mode and sweeping wavelength, detailed information of propagating waves in that waveguide has been extracted from analyses in both space and wavelength domains. Our technique needs no special steps for phase stabilization, thus allowing long-duration and environment-insensitive measurements. As a proof-of-concept test, in a silicon single-mode waveguide with a few of etched holes, the locations and reflection strengths of the inner defects have been quantified. The measurement uncertainty of the reflection amplitude is less than 25% at current stage. Our technique paves the way for non-destructively diagnosing photonic circuits on a chip with sub-wavelength spatial resolution and detailed information extraction.

Optical polarization response at gold nanosheet edges probed by scanning near-field optical microscopy

Optical properties of metallic edge-like structures known as knife-edges are a topic of interest and possess potential applications in enhanced Raman scattering, optical trapping, etc. In this work, we investigate the near-field optical polar- ization response at the edge of a triangular gold nanosheet, which is synthesized by a wet chemical method. A homemade scanning near-field optical microscope （SNOM） in collection mode is adopted, which is able to accurately locate its probe at the edge during experiments. An uncoated straight fiber probe is used in the SNOM, because it s611 preserves the prop- erty of light polarization though it has the depolarization to some extent. By comparing near-field intensities at the edge and glass substrate, detected in different polarization directions of incident light, the edge-induced depolarization is found, which is supported by the finite differential time domain （FDTD） simulated results. The depolarized phenomenon in the near-field is similar to that in the far-field.

Influence of the probe-sample interaction on scanning near-field optical microscopic images in the far field

We have studied the influence of probe-sample interaction in a scanning near-field optical microscopy （SNOM） in the far field by using samples with a step structure. For a sample with a step height of - λ/4, the SNOM image contrast between the two sides of the step changes periodically at different scan heights. For a step height of-λ/2, the image contrast remains approximately the same. The probe-sample interaction determines the SNOM image contrast here. The influence of different refractive indices of the sample has been also analysed by using a simple theoretical model.

Scanning Head for the Apertureless near Field Optical Microscope

The design and characterization of a tip control unit for an apertureless scanning near field optical microscope (ASNOM) is reported. To make the instrument operation easier, the cantilever control parts (piezo excitation of the cantilever vibration for the dynamic mode feedback and the parts necessary for the optical lever scheme of the vibration control) were placed in a separate detachable assembly. To suppress the influence of vibrations of the setup, the assembly was made lightweight. Good optical access to the ASNOM tip from various directions is provided in the system. High long-term mechanical stability of the system (~50 nm lateral drift in 18 hours) as well as low sensitivity to seismic vibrations (~400 pm RMS) is demonstrated. It is shown that external sound is not a main source of noise in the topography image (~200 pm RMS). The light field distribution (with its amplitude and phase) around the ASNOM tip was acquired by scanning the focal spot around the tip, and a high optical quality of the system is demonstrated.

Scanning transmission electron microscopy: A review of high angle annular dark field and annular bright field imaging and applications in lithium-ion batteries

Scanning transmission electron microscopy（STEM） has been shown as powerful tools for material characterization,especially after the appearance of aberration-corrector which greatly enhances the resolution of STEM. High angle annular dark field（HAADF） and annular bright field（ABF） imaging of the aberration-corrected STEM are widely used due to their high-resolution capabilities and easily interpretable image contrasts. However, HAADF mode of the STEM is still limited in detecting light elements due to the weak electron-scattering power. ABF mode of the STEM could detect light and heavy elements simultaneously, providing unprecedented opportunities for probing unknown structures of materials. Atomiclevel structure investigation of materials has been achieved by means of these imaging modes, which is invaluable in many fields for either improving properties of materials or developing new materials. This paper aims to provide a introduction of HAADF and ABF imaging techniques and reviews their applications in characterization of cathode materials, study of electrochemical reaction mechanisms, and exploring the effective design of lithium-ion batteries（LIBs）. The future prospects of the STEM are also discussed.

Design of three-dimensional imaging lidar optical system for large field of view scanning

Three-dimensional(3D)lidar has been widely used in various fields.The MEMS scanning system is one of its most important components,while the limitation of scanning angle is the main obstacle to improve the demerit for its application in various fields.In this paper,a folded large field of view scanning optical system is proposed.The structure and parameters of the system are determined by theoretical derivation of ray tracing.The optical design software Zemax is used to design the system.After optimization,the final structure performs well in collimation and beam expansion.The results show that the scan angle can be expanded from±5°to±26.5°,and finally the parallel light scanning is realized.The spot diagram at a distance of 100 mm from the exit surface shows that the maximum radius of the spot is 0.506 mm with a uniformly distributed spot.The maximum radius of the spot at 100 m is 19 cm,and the diffusion angle is less than 2 mrad.The energy concentration in the spot range is greater than 90%with a high system energy concentration,and the parallelism is good.This design overcomes the shortcoming of the small mechanical scanning angle of the MEMS lidar,and has good performance in collimation and beam expansion.It provides a design method for large-scale application of MEMS lidar.

Spherical Near-Field - Far-Field Transformation for Quasi-Planar Antennas from Irregularly Spaced Data

An effective near-field - far-field (NF - FF) transformation with spherical scanning for quasi-planar antennas from irregularly spaced data is developed in this paper. Two efficient approaches for evaluating the regularly spaced spherical samples from the nonuniformly distributed ones are proposed and numerically compared. Both the approaches rely on a nonredundant sampling representation of the voltage measured by the probe, based on an oblate ellipsoidal modelling of the antenna under test. The former employs the singular value decomposition method to reconstruct the NF data at the points fixed by the nonredundant sampling representation and can be applied when the irregularly acquired samples lie on nonuniform parallels. The latter is based on an iterative technique and can be used also when such a hypothesis does not hold, but requires the existence of a biunique correspondence between the uniform and nonuniform samples, associ- ating at each uniform sampling point the nearest irregular one. Once the regularly spaced spherical samples have been recovered, the NF data needed by a probe compensated NF - FF transformation with spherical scanning are efficiently evaluated by using an optimal sampling interpolation algorithm. It is so possible to accurately compensate known posi- tioning errors in the NF - FF transformation with spherical scanning for quasi-planar antennas. Some numerical tests assessing the accuracy and the robustness of the proposed approaches are reported.

Evaluation of Single Field Uniform Dose (SFUD) Proton Pencil Beam Scanning (PBS) Planning Strategy for Lung Mobile Tumor Using a Digital Phantom

Purpose: To quantitatively evaluate four different Proton SFUD PBS initial planning strategies for lung mobile tumor. Methods and Materials: A virtual lung patient’s four-dimensional computed tomography (4DCT) was generated in this study. To avoid the uncertainties from target delineation and imaging artifacts, a sphere with diameter of 3 cm representing a rigid mobile target (GTV) was inserted into the right side of the lung. The target motion is set in superior-inferior (SI) direction from ?5 mm to 5 mm. Four SFUD planning strategies were used based on: 1) Maximum-In-tensity-Projection Image (MIP-CT);2) CT_average with ITV overridden to muscle density (CTavg_muscle);3) CT_average with ITV overridden to tumor density (CTavg_tumor);4) CT_average without any override density (CTavg_only). Dose distributions were recalculated on each individual phase and accumulated together to assess the “actual” treatment. To estimate the impact of proton range uncertainties, +/?3.5% CT calibration curve was applied to the 4DCT phase images. Results: Comparing initial plan to the dose accumulation: MIP-CT based GTV D98 degraded 2.42 Gy (60.10 Gy vs 57.68 Gy). Heart D1 increased 6.19 Gy (1.88 Gy vs 8.07 Gy);CTavg_tumor based GTV D98 degraded 0.34 Gy (60.07 Gy vs 59.73 Gy). Heart D1 increased 2.24 Gy (3.74 Gy vs 5.98 Gy);CTavg_muscle based initial GTV D98 degraded 0.31 Gy (60.4 Gy vs 60.19 Gy). Heart D1 increased 3.44 Gy (4.38 Gy vs 7.82 Gy);CTavg_only based Initial GTV D98 degraded 6.63 Gy (60.11 Gy vs 53.48 Gy). Heart D1 increased 0.30 Gy (2.69 Gy vs 2.96 Gy);in the presence of ±3.5% range uncertainties, CTavg_tumor based plan’s accumulated GTV D98 degraded to 57.99 Gy (+3.5%) 59.38 Gy (?3.5%), and CTavg_muscle based plan’s accumulated GTV D98 degraded to 59.37 Gy (+3.5%) 59.37 Gy (?3.5%). Conclusion: This study shows that CTavg_Tumor and CTavg_Muscle based planning strategies provide the most robust GTV coverage. However, clinicians need to be aware that the actual dose to OARs at distal end of target may increase. The study also indicates that the current SFUD PBS planning strategy might not be sufficient to compensate the CT calibration uncertainty.

银耳多糖对麦醇溶蛋白纳米体系的影响及复合物的特性研究

该研究是以提高麦醇溶蛋白(gliadin,Gli)纳米颗粒(gliadin nanoparticles,GNPs)稳定性为目标,利用银耳多糖(Tremella fuciformis polysaccharides,TFPs)的乳化性能,探究TFPs添加量对GNPs稳定性的影响。采用反溶剂法制备银耳多糖和麦醇溶蛋白复合载体颗粒(gliadin-Tremella fuciformis polysaccharides composite nanoparticles,G/T NPs),并利用纳米粒度仪、傅里叶变换红外光谱仪、热场发射扫描电镜对G/T NPs的粒径和电位、相互作用、微观结构进行分析。结果表明,TFPs和Gli之间通过静电作用力和氢键作用力相结合,形成GNPs在内、TFPs外层附着的复合颗粒;TFPs的添加能够有效提高GNPs体系的稳定性,减少颗粒之间的聚集,制得的G/T_(4∶1)NPs的平均粒径、多分散指数(polydispersion index,PDI)、ζ-电位分别为(198.5±2.6)nm、0.269±0.005、(36.7±0.6)mV,且具有pH响应性。该研究为后续构建疏水营养成分的包埋和运载体系奠定了基础。

保偏光纤制备及其参数测试原理

为了研制工作波长为1310 nm的保偏光纤,采用改进的化学气相沉积工艺制备了保偏光纤预制捧和应力棒,经加工、拼接、清洗、拉丝工艺后,得到几何尺寸精确的高质量保偏光纤;同时搭建了高效测试系统,采用折射近场法、远场扫描法、视频灰度技术(传输近场),分别测量了预制棒的折射率分布和几何尺寸,保偏光纤模场直径、数值孔径、几何尺寸等关键参数。结果表明,此标准化测试系统操作流程简单、结果精确;模场直径为6.26μm,数值孔径为0.23,包涂直径80μm/135μm/165μm(精度±0.7μm);终检测试合格的光纤成品随机抽样16.25%,高低温老化实验后拍长、串音变化小。所研制的保偏光纤性能稳定,几何尺寸精确、结构均匀、损耗低,具有优良保偏性能,已广泛应用于实际生产中。

光学相控阵性能参数仿真分析与实验研究

详细介绍了一维光学相控阵的扫描特性,仿真分析了各参数之间的理论关系。通过各参数与波长之间的关系研究,可知波长调制实现纵向角度控制不会明显改变光学相控阵参数变化,论证在波导上刻蚀光栅,利用光栅的衍射特性可实现二维光学相控阵光束扫描。通过实验,实现了一种256通道光栅二维光学相控阵系统,验证了探测距离大于50 m,测距精度优于5 cm,光束发散角小于0.25°,在1515~1595 nm波长范围内,可实现41.2°×11.9°的二维扫描范围。这些理论分析和实验研究为该领域的科研工作者提供理论指导和技术支持,具有重要的应用价值。

基于孢粉学及花瓣微观形态学的玫瑰花品种的鉴定

目的对6种玫瑰花花粉粒、花瓣进行显微特征观察,以期为玫瑰花显微鉴定与品种划分提供参考。方法通过使用光学显微镜及扫描电子显微镜对6种玫瑰花的花粉粒和花瓣形貌进行观察,并对花粉粒的9个孢粉学特征指标进行量化分析。结果6种玫瑰花的花粉粒类型均为等级单粒的N_(3)P_(4)C_(5)型,均具沿极轴方向向两极延伸的条状纹饰。其孢粉学数据结果显示:内孔宽度(We)变异系数过大,不能作为鉴别依据;其它指标包括极轴长(P)、赤道轴长(E)、P/E值、外孔长度(Le)、花粉壁沿极轴长度(Exp)、花粉壁沿赤道轴长度(Exe)、花粉壁沿极轴相对厚度(Exe/P)以及花粉壁沿赤道轴相对厚度(Exe/E)差异明显,可综合应用对6种玫瑰花进行品种鉴定。6种玫瑰花花瓣近轴面乳突结构及远轴面条纹形成的盘状结构差异较大,可作为6个品种的鉴别依据。结论从微观角度对6种玫瑰花花瓣微形貌、花粉粒特征及孢粉学研究,为不同品种玫瑰花的鉴别提供了参考依据。

船舶板架结构变形场测量技术研究

船舶结构强度试验过程中,传统的离散点变形测量技术难以获得结构的全场变形数据,因而无法有效揭示结构的渐进破坏过程。本文基于数字图像相关和三维激光扫描原理,提出适用于船舶板架结构变形测量的位移形函数与子区相关性准则,发展定量可控的数字散斑场制作方法,形成船舶板架结构几何形貌测量方法,建立船舶板架结构变形场测量技术;在此基础上,开展船舶板架结构模型变形场演化过程测量试验,获得模型在纵向压缩载荷所用下的结构变形场,尤其是模型结构临界状态前后的失效演化行为,揭示船舶板架结构变形场的时空演化规律,可为实船结构的失效模式识别提供基础测量技术手段。

Daytona超广角激光扫描眼底成像与FFA在老年白内障病人糖尿病性视网膜病变筛查中的一致性分析

目的探讨Daytona超广角激光扫描眼底成像与荧光素眼底血管造影(fundus fluorescein angiography,FFA)筛查老年白内障病人糖尿病性视网膜病变(diabetic retinopathy,DR)的一致性。方法采用横断面研究方法,选取2021年4月至2023年8月在大庆油田总医院眼科门诊就诊的年龄≥60岁合并糖尿病的老年白内障病人172例(323眼),所有病人均接受Daytona超广角激光扫描眼底成像以及FFA检查,分别记录2种检查方法诊断DR以及DR分期情况。采用卡方检验、加权Kappa一致性检验、Spearman偏回归分析对2种检查结果的相关性进行分析。结果2种检查方法的可阅片率差异无统计学意义(93.8%比94.1%,P=0.869)。Daytona超广角系统检查时间较FFA检查时间明显缩短(Z=16.85,P<0.001)。排除未得到眼底图像25眼,最终153例298眼纳入一致性研究。Daytona超广角系统与FFA检测DR分期完全一致278只眼(93.29%),Kappa值为0.925,95%CI:0.892~0.958。以FFA为金标准,Daytona超广角系统检测增生型DR的敏感度和特异度分别为90.00%、100.00%,Kappa值为0.926;检测非增生型DR的敏感度、特异度分别为94.47%、90.91%,Kappa值为0.900。Daytona超广角系统与FFA检测DR分期结果呈高度正相关(r=0.921)。结论Daytona超广角激光扫描眼底成像对合并糖尿病的老年白内障病人DR筛查效果及分期与FFA有很好的一致性。

基于多面无相位近场数据的电磁干扰源等效建模

针对现有无相位近场数据的偶极子建模很难精确对干扰源进行等效的问题,对现有无相位近场数据的干扰源等效建模中所采用的双面迭代方法进行了改进,改进方法主要是采用2个以上不同高度的磁场幅度数据;对双面迭代方法中平面的选择以及改进方法中平面数量和起始面的选择进行了讨论;以干扰源辐射磁场重构的均方根误差(Root Mean Square Error,RMSE)作为偶极子建模准确度评价依据,与现有双面迭代方法及其他优化方法等效建模出的偶极子模型进行了对比验证,对比结果显示该改进方法具有更高的准确度。