基于成像球光强测量系统的光学设计

提出一种新的快速测量空间光强分布的方法,完成基于该方法测量系统的光学系统设计,并对光学系统的关键器件进行设计.利用Matlab编程和Solidworks三维建模得到自由曲面反射镜面型,Zemax光学软件设计优化得到双高斯物镜.光线追踪仿真软件LightTools对测量系统进行模拟仿真,验证系统的可行性,并对该构架下测量系统最小角分辨率和动态范围的关键性能指标进行分析.结果表明,设计的基于成像球的测量系统可实现空间光强分布测量.

基于点源成像的微球成像分辨能力仿真分析

基于微球透镜的显微成像技术具有方法简单、无需标记等优点,近年来受到了国内外众多研究者的关注。微球透镜成像系统参数变化将直接影响分辨能力,然而,目前缺乏此方面的仿真分析工作。因此,基于点源成像,提出了一种分析微球透镜成像分辨能力的方法,仿真分析了微球尺寸以及微球和点光源距离变化对成像分辨能力的影响。结果表明,成像分辨能力随微球尺寸的增大而下降,微球和点光源距离小于800 nm时,分辨能力随距离的增加呈下降趋势,当距离大于800 nm时,分辨能力不再发生明显变化。仿真结果对微球透镜显微成像实验具有指导意义,提出的方法为仿真分析微球成像分辨能力的研究工作提供了理论基础。

基于一体化微球物镜的超分辨成像系统

利用直径微米量级的透明微球与传统光学显微镜相结合,可以在白光下实现超分辨成像.目前大部分研究是将微球直接播撒到样品表面,由于微球位置的随机性和不连续性导致无法实现特定区域的完整成像,极大限制了该技术的使用范围.使用微探针或微悬臂黏附微球,通过三维位移台精确控制微球位置,一定程度上解决了上述问题,但是需要对微球位置进行精准操控.本文提出了一种结构稳定、参数可控、简单易用的基于一体化微球物镜的超分辨成像系统,对微球与物镜进行了一体化安装设计,通过设计侧视成像及位置反馈系统实现了对微球、物镜和样品三者之间距离的精准控制,结合通用的显微成像系统,实现了对可控特定区域的超分辨成像.该系统将普通显微物镜(40×,NA 0.6)的分辨能力提高了4.78倍,最高可以看到100 nm的样品特征.该一体化物镜可以搭配普通光学显微系统使用,实现超分辨成像,提高了微球超分辨技术的通用性,在亚衍射极限样品的超分辨成像方面具有广泛的应用价值.

我国研制成功光学成像新系统

我国科学家近日研制出了一套具有大视角、免对焦等先进功能的新型光学成像系统。这项名为“二元光学半球视场成像技术”的新成果原理与常规的光学系统成像原理不同，它将二元光学与半球成像系统结合，获得大视场凝视，不仅结构更加轻巧，而且不用调焦就能获得清晰图像。这一系统在空间光学、海洋光学等领域应用时，无需转动部件即可获得水平视场达170度的图像，并可自动消除大气、海水等因素造成的环境干扰，获得精确的目标捕获。

适用于大视场CME观测的侧面遮拦式外掩体设计

针对当前中国空间太阳观测任务中大视场日冕仪杂散光抑制需求,提出一种适用于大视场日冕物质抛射(CME)观测的日球层成像仪侧面遮拦式外掩体设计,通过在外掩体上设置多阶挡光环结构,对进入相机视场的衍射光进行抑制。基于菲涅尔-基尔霍夫衍射理论,开展组件抑制能力仿真分析,并探索不同挡光环间距、挡光环阶数、挡光环后截距等参数对于组件性能的影响。通过搭建一种适用于微弱杂散信号的测试系统,应用微光探测器和微光照度计,从图像和数值方面对组件性能进行验证。研究结果表明,经优化后的侧面遮拦式外掩体在十万级洁净度条件下杂散光抑制水平优于10–9,能够满足大视场CME观测的杂散光抑制要求。

基于空间共线点的单光心反射折射摄像机标定

一条空间直线的单光心反射折射图像是一个二次曲线段,大多数利用直线进行单光心反射折射摄像机标定的方法都需要对直线的像进行二次曲线拟合,曲线拟合的精度严重影响着标定的精度.然而,一条空间直线的像仅占整个二次曲线的一小段,这使得曲线拟合的效果非常差.本文利用空间三个共线点的反射折射投影给出了摄像机内参数的一个非线性约束.当反射镜面为抛物面时,在主点已知的情况下,该约束变为线性约束.如其他参数已知,该约束变为关于有效焦距的多项式约束.由此,本文提出了三种不同条件下的标定算法,算法中无需对直线的像进行二次曲线拟合,无需场景的任何信息,标定精度较高.实验验证了算法的有效性.

Landslide monitoring in southwestern China via time-lapse electrical resistivity tomography

The dynamic monitoring of landslides in engineering geology has focused on the correlation among landslide stability,rainwater infiltration,and subsurface hydrogeology.However,the understanding of this complicated correlation is still poor and inadequate.Thus,in this study,we investigated a typical landslide in southwestern China via time-lapse electrical resistivity tomography（TLERT） in November 2013 and August 2014.We studied landslide mechanisms based on the spatiotemporal characteristics of surface water infiltration and flow within the landslide body.Combined with borehole data,inverted resistivity models accurately defined the interface between Quaternary sediments and bedrock.Preferential flow pathways attributed to fracture zones and fissures were also delineated.In addition,we found that surface water permeates through these pathways into the slipping mass and drains away as fissure water in the fractured bedrock,probably causing the weakly weathered layer to gradually soften and erode,eventually leading to a landslide.Clearly,TLERT dynamic monitoring can provide precursory information of critical sliding and can be used in landslide stability analysis and prediction.

The spatial distribution characteristics of shallow fissures of a landslide in the Wenchuan earthquake area

Shallow fissures, being the main infiltration paths of fluid on the surface of a slope, played an important role in the whole process of a landslide. However, the spatial distribution characteristics of fissures in the slope are difficult to be determined. In this study, we attempted to characterize the variation pattern of slope fissures along depth in the Wenchuan earthquake area in Sichuan Province by combining engineering geological investigation, geomorphologic analysis and geophysical investigation. The geophysical methods that were used in this study include Multichannel Analysis of Surface Wave(MASW), Ground Penetrating Radar(GPR) and Electrical Resistivity Tomography(ERT). The results suggested that geophysical parameters(shear wave velocity, electromagnetic signals attenuation and resistivity) could provide valuable information for the spatial network of shallow fissures. Through the verification by engineering geological survey and geophysical sensitivity analysis, this work highlighted that MASW was the most appropriate technique to delineate the propagation of shallow fissures in a gravel soil slope.

A case of gas gangrene in an immunosuppressed Crohn's patient

Clostridium septicum(C.septicum)gas gangrene is well documented in the literature,typically in the setting of trauma or immunosuppression.In this paper,we report a unique case of spontaneous clostridial myonecrosis in a patient with Crohn's disease and sulfasalazineinduced neutropenia.The patient presented with left thigh pain,vomiting and diarrhea.Blood tests demonstrated a profound neutropenia,and magnetic resonance imaging of the thigh confirmed extensive myonecrosis.The patient underwent emergency hip disarticulation,followed by hemicolectomy.C.septicum was cultured from the blood.Following completion of antibiotic therapy,the patient developed myonecrosis of the right pectoral muscle necessitating further debridement,and remains on lifelong prophylactic antibiotic therapy.

Feasibility of using the magnetoteliuric method for sub-basalt imaging at Kachchh, India

The magnetotelluric （MT） method has been among the favorite supporting tools for seismic imaging of sub-salt and sub-basalt targets. In this paper we present an example from Kachchh, India （where basaltic rocks overlie Mesozoic sedimentary rocks）, and discuss the feasibility of using MT method as an exploration tool in this geological setting. Our results highlight the difference in magnetotelluric response caused by the thin intrabasalt layering. The key issue addressed in this paper is what MT can and cannot provide in such geological settings. First, we compute apparent resistivity and phase response curves using representative resistivity-depth models and borehole data from the study area. Later, we compare these results to assess the plausibility of using MT to image the sub-volcanic sediments at Kachchh. Finally, we substantiate our discussion through one-dimensional inversion of the field observed MT data from this region that exhibits poor sensitivity of MT for thin basalt layers.

Global Water Vapor Content Decreases from 2003 to 2012： An Analysis Based on MODIS Data

Water vapor in the earth′s upper atmosphere plays a crucial role in the radiative balance, hydrological process, and climate change. Based on the latest moderate-resolution imaging spectroradiometer(MODIS) data, this study probes the spatio-temporal variations of global water vapor content in the past decade. It is found that overall the global water vapor content declined from 2003 to 2012(slope b = –0.0149, R = 0.893, P = 0.0005). The decreasing trend over the ocean surface(b = –0.0170, R = 0.908, P = 0.0003) is more explicit than that over terrestrial surface(b = –0.0100, R = 0.782, P = 0.0070), more significant over the Northern Hemisphere(b = –0.0175, R = 0.923, P = 0.0001) than that over the Southern Hemisphere(b = –0.0123, R = 0.826, P = 0.0030). In addition, the analytical results indicate that water vapor content are decreasing obviously between latitude of 36°N and 36°S(b = 0.0224, R = 0.892, P = 0.0005), especially between latitude of 0°N and 36°N(b = 0.0263, R = 0.931, P = 0.0001), while the water vapor concentrations are increasing slightly in the Arctic regions(b = 0.0028, R = 0.612, P = 0.0590). The decreasing and spatial variation of water vapor content regulates the effects of carbon dioxide which is the main reason of the trend in global surface temperatures becoming nearly flat since the late 1990 s. The spatio-temporal variations of water vapor content also affect the growth and spatial distribution of global vegetation which also regulates the global surface temperature change, and the climate change is mainly caused by the earth's orbit position in the solar and galaxy system. A big data model based on gravitational-magmatic change with the solar or the galactic system is proposed to be built for analyzing how the earth's orbit position in the solar and galaxy system affects spatio-temporal variations of global water vapor content, vegetation and temperature at large spatio-temporal scale. This comprehensive examination of water vapor changes promises a holistic understanding of the global climate change and potential underlying mechanisms.

A Preliminary Global Analysis of Remotely Sensed Radiation Characteristics of Ground Features: Ⅰ. Methodology and Results

A Landsat data transformation method which was proposed by the author was applied to extract useful information from data of 769 ground feature classification units of worldwide scope.Three most important characteristic values--the general radiance level L,the visible-infrared radiation balance B and the band radiance variation vector (direction and speed) V were calculated.Then the 769 class units were sorted into 106 groups based on their natural characteristics.The means and standard deviations of L,B and V values for all the groups were calculated.The distributions of the 106 groups or the 769 units on the number axes of L,B and V,in the planes of L-B,L-V and B-V,and in the space of L-B-V were investigated.Finally,the typical numerical characteristics of the various ground features are discussed in consideration of their worldwide variations in the present paper.

A Thin Cloud Removal Method from Remote Sensing Image for Water Body Identification

In this paper,a thin cloud removal method was put forward based on the linear relationships between the thin cloud reflectance in the channels from 0.4 μm to 1.0 μm and 1.38 μm.Channels of 0.66 μm,0.86 μm and 1.38 μm were chosen to extract the water body information under the thin cloud.Two study cases were selected to validate the thin cloud removal method.One case was applied with the Earth Observation System Moderate Resolution Imaging Spectroradiometer(EOS/MODIS) data,and the other with the Medium Resolution Spectral Imager(MERSI) and Visible and Infrared Radiometer(VIRR) data from Fengyun-3A(FY-3A).The test results showed that thin cloud removal method did not change the reflectivity of the ground surface under the clear sky.To the area contaminated by the thin cloud,the reflectance decreased to be closer to the reference reflectance under the clear sky after the thin cloud removal.The spatial distribution of the water body area could not be extracted before the thin cloud removal,while water information could be easily identified by using proper near infrared channel threshold after removing the thin cloud.The thin cloud removal method could improve the image quality and water body extraction precision effectively.

Estimation of aerosol properties over the Chinese desert region with MODIS AOD assimilation in a global model

A Local Ensemble Transform Kalman Filter assimilation system has been implemented into an aerosol-coupled global nonhydrostatic model to simulate the aerosol mass concentration and aerosol optical properties of 3 desert sites(Ansai, Fukang, Shapotou) in northwestern China. One-month experiment results of April 2006 reveal that the data assimilation can correct the much overestimated aerosol surface mass concentration, and has a strong positive effect on the aerosol optical depth(AOD) simulation, improving agreement with observations. Improvement is limited with the?ngstr€om Exponent(AE) simulation, except for much improved correlation coefficient and model skill scores over the Ansai site. Better agreement of the AOD spatial distribution with the independent observations of Terra(Deep Blue) and Multi-angle Imaging Spectroradiometer(MISR) AODs is obtained by assimilating the Moderate Resolution Imaging Spectroradiometer(MODIS) AOD product, especially for regions with AODs lower than 0.30. This study confirms the usefulness of the remote sensing observations for the improvement of global aerosol modeling.

Synthesis of amphiphilic poly(fluorene) derivatives for selective imaging of Staphylococcus aureus

Three amphiphilic poly（fluorene-co-phenylene） derivatives with different side chains （PFP-I, PFP-2, PFP- 3） were designed and synthesized for exploring their detection and imaging of pathogens. Upon incuba- tion with six kinds of different pathogens, it was found the three polymers could selectively interact with Staphylococcus oureus （S. aureus）. Their selective imaging towards S. aureus were thus realized. The selective imaging towards S. aureus was also confirmed even under the blend of microbes. PFP-3 shows stronger fluorescence imaging signal than PFP-1 and PFP-2. Zeta potential and isothermal titration microcalorimetry （ITC） tests demonstrated that both electrostatic interactions and hydrophobic interac- tions played important roles in the binding between PFPs and pathogens. Thus, amphiphilic PFP-3 exhi- bits great potential for specific imaging ors. aureus in a simple and rapid manner.

Role of endoscopy in inflammatory bowel disease

Crohn’s disease(CD)and ulcerative colitis(UC)constitute the twomost common phenotypes of inflammatory bowel disease(IBD).Ileocolonoscopy with biopsy has been considered the gold standard for the diagnosis of IBD.Differential diagnosis of CD and UC is important,as theirmedical and surgical treatmentmodalities and prognoses can be different.However,approximately 15%of patients with IBD aremisdiagnosed as IBD unclassified due to the lack of diagnostic certainty of CD or UC.Recently,there has been increased recognition of the role of the therapeutic endoscopist in the field of IBD.Newer imaging techniques have been developed to aid in the differentiation of UC vs CD.Furthermore,endoscopic balloon dilation and stenting have become an integral part of the therapeutic armamentariumof CD stricturemanagement.Endoscopic ultrasound has been recognized as beingmore accurate thanmagnetic resonance imaging in detecting perianal fistulae in patientswith CD.Additionally,chromoendoscopymay help to detect dysplasia earlier compared with white-light colonoscopy.Hence,interventional endoscopy has become a cornerstone in the diagnosis,treatment andmanagement of IBD complications.The role of endoscopy in the field of IBD has significantly evolved in recent years fromsmall-bowel imaging to endoscopic balloon dilation and use of chormoendoscopy in dysplasia surveillance.In this reviewarticle,we discuss the current evidence on interventional endoscopy in the diagnosis,treatment andmanagement of IBD compications.

Reflection full waveform inversion

Because of the combination of optimization algorithms and full wave equations, full-waveform inversion(FWI) has become the frontier of the study of seismic exploration and is gradually becoming one of the essential tools for obtaining the Earth interior information. However, the application of conventional FWI to pure reflection data in the absence of a highly accurate starting velocity model is difficult. Compared to other types of seismic waves, reflections carry the information of the deep part of the subsurface. Reflection FWI, therefore, is able to improve the accuracy of imaging the Earth interior further. Here, we demonstrate a means of achieving this successfully by interleaving least-squares RTM with a version of reflection FWI in which the tomographic gradient that is required to update the background macro-model is separated from the reflectivity gradient using the Born approximation during forward modeling. This provides a good update to the macro-model. This approach is then followed by conventional FWI to obtain a final high-fidelity high-resolution result from a poor starting model using only reflection data.Further analysis reveals the high-resolution result is achieved due to a deconvolution imaging condition implicitly used by FWI.

Lunar absolute reflectance as observed by Chang'E-1 Imaging Interferometer

Lunar absolute reflectance, which describes the fraction of solar radiation reflected by the Moon, is fundamental for the Chang'E-1 Imaging Interferometer(IIM) to map lunar mineralogical and elemental distributions. Recent observations made by the Spectral Irradiance Monitor(SIM) onboard the Solar Radiation and Climate Experiment(SORCE) spacecraft indicate that temporal variation in the solar radiation might have non-negligible influence on reflectance calculation, and the SIM measurements are different from the two previously used solar irradiances, i.e., ATLAS3 and Newkur. To provide reliable science results, we examined solar irradiance variability with the SIM daily observations, derived lunar absolute reflectances from the IIM 2A radiance with the SIM, ATLAS3 and Newkur data, and compared them with the Chandrayaan-1 Moon Mineralogy Mapper(M3), the Robotic Lunar Observatory(ROLO) and the Kaguya Multispectral Imager(MI) results. The temporal variability of the SIM solar irradiance is 0.25%–1.1% in the IIM spectral range, and less than 0.2% during the IIM observations. Nevertheless, the differences between the SIM measurements and the ATLAS3 and Newkur data can respectively rise up to 8% and 5% at particular IIM bands, resulting in discrepancy between which might affect compositional mapping. The IIM absolute reflectance we derived for the Moon using the SIM data, except for the last two bands, is consistent with the ROLO and the MI observations, although it is lower.

Re-examining Photodetachment of H^- near a Spherical Surface using Closed-Orbit Theory

Photodeachment of H^-near a reflective spherical surface was studied by Haneef et al.[J.Phys.B:At.Mol.Opt.Phys.44(2011)195004]using a theoretical imaging method.The total cross section displays interesting oscillations.Here we re-examine the total photodetachment cross section of this system by directly applying the standard closed-orbit theory.Our result for the total cross section differs from the result obtained by Haneef et al.The difference between the two results vanishes in the limit of large radius of the reflective sphere.We argue that the theoretical imaging method developed originally for photodetachment near a Hat surface can not be directly applied to the present system.

Lunar titanium abundance characterization using Chang'E-1 IIM data

Lunar titanium characterization is an important goal of the China Lunar Exploration Program. We suggest a method to determine the lunar titanium abundance using Chang'E-1 IIM (Interference Imaging Spectrometer) imagery. Using samples from Apollo and Luna landing sites, the method firstly establishes the spectral parameters that possess good non-linear correlations with lunar titanium abundance. Secondly, the method estimates lunar titanium abundance using a DT-SVM (Decision Tree Method C5.0-Support Vector Machine) method. Namely, according to the established spectral parameters, it uses the C5.0 algorithm to classify the titanium abundance into the 4 classes of very low, low, intermediate and high. Then, in terms of the spectral parameters and the corresponding classes, it employs the SVM to estimate the titanium abundance. The method makes good use of hyperspectral information, analyzes the nonlinear correlations between spectral characteristics of lunar soils and the composition parameter, and well determines the titanium abundance. Validated by the Apollo and Luna station samples, the RMSE (root mean square error) is 0.72wt% TiO2 and the correlation coefficient of the measured and predicted values is 97.29%. So, the method proposed in this paper has a good predictive capability for TiO2 abundance on the lunar surface. The maps of TiO2 content in the partial region of Sinus Iridium, the Apollo 17 landing site and the Apollo 16 landing site are constructed by our method. This paper demonstrates the potential of IIM data for the investigation of lunar surface chemistry and mineralogy.