双层塑料靶丸的X射线相衬成像

 为对微聚焦X射线相衬成像技术应用于双层以及多层塑料靶丸成像和特征分析进行可行性研究,基于类同轴X射线成像技术,综合考虑成像放大倍数、分辨率和衬度等因素,选择合适的实验参数,成功获得了较为清晰的双层塑料靶丸X射线相衬成像照片;采用数字图像处理技术的图像分割手段,如拉普拉斯高斯边缘检测法等对所成像中靶丸边界特征进行分析处理,获得了双层靶丸内层厚度为（10.5±0.6） μm,外层厚度为（9.2±0.7） μm,靶丸外径为（273.3±1.0） μm等参数。     

频谱编码深度成像实验研究

频谱编码显微镜是用衍射光栅和光谱分析装置来获得显微图像.样品上不同的位置被不同的波长照明,通过对反射光光谱进行解码来得到空间信息.搭建了一个基于超连续光源和自制光谱仪的频谱编码显微成像系统,其横向分辨率为1.72±0.13μm(编码线方向)和1.26±0.08μm(垂直于编码线方向),测得不同横向位置处的轴向分辨率有差异.对离体猪肝组织不同部位进行了成像(可见血管、肝窦内皮细胞和肝细胞);对鸡心组织以10μm深度间隔进行成像,测得不同深度处结构信息不一样.结果表明,采用该频谱编码成像的方法能够进行高分辨的深度成像.     

双色荧光辐射差分超分辨显微系统研究

为了拓展荧光辐射差分(Fluorescence Emission Difference,FED)显微术的应用,使得该方法可以同时对生物样品的不同组织结构进行超分辨成像,本文对双色FED显微系统展开了研究。FED的基本原理是将实心光斑扫描得到的共焦显微图像减去空心光斑扫描得到的负共焦图像,以此获得超分辨显微图像。在对单色FED显微系统进行研究后,本文提出了一种可行的双色FED显微成像系统方案。实验结果表明,在488 nm和640 nm激发光下,该系统在荧光颗粒上分别实现了135 nm和160 nm的空间分辨率,另外也能对生物样品的不同组织进行多色同时超分辨显微成像,满足了实际应用的要求。     

基于双螺旋点扩散函数工程的多焦点图像扫描显微

在传统共聚焦显微技术的基础上,图像扫描显微技术使用面阵探测器来代替单点探测器,结合虚拟数字针孔并利用像素重定位和解卷积图像重构算法将传统宽场显微镜的分辨率提高一倍,实现了高信噪比的超分辨共焦成像.但是,由于采用逐点扫描的方式,三维成像速度相对较慢,限制了其在活体样品成像中的应用.为了进一步提高图像扫描显微术的成像速度,本文提出了一种基于双螺旋点扩散函数工程的多焦点图像扫描显微成像方法和系统.在照明光路中,利用高速数字微镜器件产生周期分布的聚焦点阵对样品进行并行激发和快速二维扫描;在探测光路中,利用双螺旋相位片将激发点荧光信号的强度分布转换为双螺旋的形式;最终,利用后期数字重聚焦处理,从单次样品扫描数据中重构出多个样品层的超分辨宽场图像.在此基础上,利用搭建的系统分别对纤维状肌动蛋白和海拉细胞线粒体进行成像实验,证明了该方法的超分辨能力和快速三维成像能力.     

Characterization of carbon nanotubes by scanning probe microscopy

Carbon nanotubes, fabricated by the Ebbesen-Ajayan method, were imaged using scanning tunneling microscopy (STM) and atomic force microscopy (AFM) in air and were compared to images obtained with high-resolution transmission electron microscopy (HRTEM). The HRTEM images revealed an abundance of elongated structures ranging in diameter from 3.0 to 30 nm, and with lengths of up to 0.8 μm. Many of the structures possessed several graphitic shells as if the tubes were nested one in the other. Reproducible images of the tubular structures, typically 20 nm in diameter and with a large variation in length, were obtained with both STM and AFM when the nanotubes were deposited on hydrogen-terminated Si(111), confirming that the nested structures observed with HRTEM do indeed have a tubular morphology. No single-walled, bare nanotubes or spherical fullerenes (typical of the Krätschmer-Huffman process) were observed.     

基于高光谱图像技术的水果表面农药残留检测试验研究

以脐橙为研究对象,初步探讨了应用高光谱图像技术检测水果表面农药残留的方法.用蒸馏水把农药分别配置成1:20,1:100和1:1000倍的溶液.然后把同种不同浓度的溶液滴到10个洗净的脐橙表面,溶液量约为120 μL,200μL和400μL,脐橙表面形成一个3×3的矩阵形状.将水果放置到通风阴凉处放168 h后,拍摄图像.采集脐橙在625～725 nm范围的高光谱图像,应用主成分分析方法(PCA)获得特征波长的图像,应用第三主成分图像(PC-3)并经过适当的图像处理方法对脐橙表面的农药残留进行检测.检测结果表明,高光谱技术对检测较高浓度农药残留非常明显.     

基于声光滤光和液晶相位调谐的高光谱全偏振成像新技术

为了获取高光谱分辨率、高空间分辨率、高偏振精度、高信噪比和稳定性好的全部Stokes参量光谱图像, 考虑到声光可调谐滤光器(acousto-optical tunable filter, AOTF)的±1级衍射光的正交特性, 提出用一个AOTF滤光, 一个液晶可变延迟器(liquid crystal variable retarder, LCVR)进行相位调制和两个CCD相机分别对±1级衍射光成像的高光谱全偏振成像新技术. 从所采用的光学元件的穆勒矩阵出发, 阐述了该技术的基本工作原理; 理论分析表明, LCVR不但不会影响到第一个Stokes参量的探测精度, 而且后3个Stokes参量的相对误差分别优于0.064%, 0.31%和3.97%; 利用原理样机获取了450–700 nm、光谱带宽为10 nm的26个光谱通道的图像数据, 成像质量良好; 以工作波长为600 nm的入射光为例, 对其全部Stokes参量图像进行了具体分析讨论. 结果表明, 该新技术原理正确, 方案可行. 该研究可为光谱偏振成像技术提供新的理论和实现方案.     

Superresolution vibrational imaging by simultaneous detection of Raman and hyper-Raman scattering

We have developed a superresolution vibrational imaging method by simultaneous detection of Raman and hyper-Raman scattering. Raman and hyper-Raman images obtained with the same laser spot carry independent information on the sample spatial distribution, owing to different signal dependence (linear in Raman and quadratic in hyper-Raman) on the incident light intensity. This information can be quantitatively analyzed to recover the incident light intensity distribution at the focal plane. A superresolution vibrational image is then derived by the constrained deconvolution of the images by the obtained incident light intensity distribution. This method has been applied to a TiO? nanostructure and the obtained superresolution image was compared with a scanning electron microscopy image. The spatial resolution achieved by the present method is evaluated to be 160 nm, which is more than twice better than the diffraction limited resolution.     

X-ray absorption spectroscopy in total electron yield mode of scanning photoelectron microscopy

Total electron yield (TEY) measurement was applied to the scanning photoelectron microscopy (SPEM). The resultant image showed the thickness variation of a zinc overlayer deposited on an iron substrate with 18 nm nominal thickness. The contrast and signal-to-noise ratio of the image were much higher than those of the images obtained by the conventional SPEM. When the order-sorting aperture (OSA) located between the Fresnel zone plate and the sample was biased to +80 V relative to the sample, the contrast of the image was further improved. It also made it possible to perform microscopic X-ray absorption spectroscopy in TEY mode by preventing the unwanted photoelectrons emitted from the OSA, which can cause false TEY, from reaching the sample. Oxidized areas of the iron substrate under the thick zinc overlayer were clearly identified.     

Scanning ion conductance microscopy for imaging biological samples in liquid: a comparative study with atomic force microscopy and scanning electron microscopy

The present study was designed to show the applicability of scanning ion conductance microscopy (SICM) for imaging different types of biological samples. For this purpose, we first applied SICM to image collagen fibrils and showed the usefulness of the approach-retract scanning (ARS)/hopping mode for such samples with steep slopes. Comparison of SICM images with those obtained by AFM revealed that the ARS/hopping SICM mode can probe the surface topography of collagen fibrils and chromosomes at nanoscale resolution under liquid conditions. In addition, we successfully imaged cultured HeLa cells, with 15 μm in height by ARS/hopping SICM mode. Because SICM can obtain non-contact (or force-free) images, delicate cellular projections were visualized on the surface of the fixed cell. SICM imaging of live HeLa cells further demonstrated its applicability to study the morphological dynamics associated with biological processes on the time scale of minutes under liquid conditions. We further applied SICM for imaging the luminal surface of the trachea and succeeded in visualizing the surface of both ciliated and non-ciliated cells. These SICM images were comparable with those obtained by scanning electron microscopy. Although the dynamic mode of AFM provides better resolution than the ARS/hopping mode of SICM in some samples, only the latter can obtain contact-free images of samples with steep slopes, rendering it an important tool for observing live cells as well as unfixed or fixed soft samples with complicated shapes. Taken together, we demonstrate that SICM imaging, especially using an ARS/hopping mode, is a useful technique with unique capabilities for imaging the three-dimensional topography of a range of biological samples under physiologically relevant aqueous conditions.     

High Speed Terahertz Pulse Imaging in the Reflection Geometry and Image Quality Enhancement by Digital Image Processing

We describe the formation and enhancement of two dimensional pulsed terahertz (THz) images obtained in the reflection geometry with a high-speed optical delay line. Two test objects are imaged and analyzed with respect to material information and concealed structure. Clear THz images were obtained with various imaging modes and were compared with the X-ray images. The THz image of a sample revealed material features that the X-ray image cannot distinguish. We could enhance the THz image quality using various image processing techniques, such as edge detection, de-noising, high-pass filtering, and wavelet filtering.     

浅海被动水下偏振成像探测方法

针对传统被动水下偏振成像方法忽略水体对光的吸收效应,成像结果中存在严重的色彩失真,且并未深入发掘利用背景散射光中包含的场景信息的问题.提出浅海被动水下偏振成像探测方法,该方法从水体中背景散射光的传输特性出发,分析场景深度信息与散射光的物理关系,建立基于深度信息的水下Lambertian反射模型,实现无色彩畸变的水下目标场景清晰成像探测.实验结果表明,该方法能够提供接近水下目标真实色彩、符合人眼视觉特性的清晰探测结果,提高水下成像探测能力.     

Holographic imaging with a nanometer resolution using compact table-top EUV laser

Holographic 2D/3D imaging with nanometer resolution using short wavelength extreme ultraviolet (EUV) light is presented in this paper. Gabor’s holograms were recorded with a highly coherent table top EUV laser with different numerical apertures demonstrating ultimately a spatial resolution of 46+/−2 nm, comparable with the illumination wavelength, in 2D holographic imaging. Three dimensional images were obtained from a single high numerical aperture hologram recorded in a high resolution photoresist and numerically reconstructed at different image planes, allowing numerical optical sectioning with a lateral resolution ∼170 nm and depth resolution of 2.4 μm. The holograms were recorded in a high resolution photoresist and digitized with an atomic force microscope. To assess the spatial resolution of the numerical reconstructions of the holograms a correlation method was used. The algorithm allows for simultaneous estimation of the resolution and the feature size of the image under analysis.     

Assessment of acute myocardial infarction in man with magnetic resonance imaging and the use of a new paramagnetic contrast agent gadolinium-bopta

To assess the feasibility of and characterize the new paramagnetic contrast agent gadolinium-BOPTA/dimeglumine (Gd-BOPTA) to detect acute myocardial infarctions with MR imaging, 24 patients (53.3 ± 8.3 yr) were examined 9.3 ± 3.6 days after a first myocardial infarction. Short-axis T₁-weighted and T₂-weighted MR imaging was performed at three slice levels. T₁-weighted images were obtained before, immediately after, 15, 30, and 45 min after injection. Patients received either 0.05 or 0.1 mmol/kg body weight Gd-BOPTA. Images were qualitatively and quantitatively analyzed. Two patients showed no signs of infarction on T₂-weighted images as opposed to contrast-enhanced T₁-weighted images. Contrast-to-noise ratio was not affected by the dosage level. Signal intensity (SI) of normal to infarcted myocardium was significantly improved by both dosages (p < .0005) but a dosage of 0.05 mmol/kg produced significantly higher SI inf/norm (1.42 ± 0.07 vs. 1.34 ± 0.06, respectively, p = .015). SI of normal and infarcted myocardium enhanced immediately after administration of 0.05 mmol/kg (29.3 ± 5.1% and 53.8 ± 9.6% respectively), which decreased thereafter to 5.3 ± 4.8% and 40.2 ± 8.5% respectively, at 45 min (p < .002 for normal myocardium). SI enhancement immediately after 0.1 mmol/kg Gd-BOPTA showed no decrease within the first 45 min. Gd-BOPTA enables the detection of myocardial infarction. Optimal infarct delineation is achieved from 15 to 45 min after administration of 0.05 mmol/kg body weight Gd-BOPTA. Gd-BOPTA at 0.05 mmol/kg does improve image quality as measured by contrast-to-noise ratio and SI enhancement as compared to 0.10 mmol/kg.     

When optical microscopy meets all-optical analog computing: A brief review

As a revolutionary observation tool in life science, biomedical, and material science, optical microscopy allows imaging of samples with high spatial resolution and a wide field of view. However, conventional microscopy methods are limited to single imaging and cannot accomplish real-time image processing. The edge detection, image enhancement and phase visualization schemes have attracted great interest with the rapid development of optical analog computing. The two main physical mechanisms that enable optical analog computing originate from two geometric phases: the spin-redirection Rytov-Vlasimirskii-Berry (RVB) phase and the Pancharatnam-Berry (PB) phase. Here, we review the basic principles and recent research progress of the RVB phase and PB phase based optical differentiators. Then we focus on the innovative and emerging applications of optical analog computing in microscopic imaging. Optical analog computing is accelerating the transformation of information processing from classical imaging to quantum techniques. Its intersection with optical microscopy opens opportunities for the development of versatile and compact optical microscopy systems.     

光学微操纵过程的轴平面显微成像技术

光学俘获技术利用光与物质相互作用产生的光势阱效应来实现对微粒的操控,已经成功应用于生物医学、材料科学等交叉领域.在对微粒进行三维俘获时,传统的宽场光学显微技术只能观测到某一平面内微粒的横向运动,对微粒沿轴向运动的观测受到很大限制.本文将轴平面显微成像技术引入光学微粒操控研究中,利用45?倾斜的反射镜把微粒的轴向运动信息转换到横向平面进行观测,与传统宽场显微成像技术相结合,实现了对二氧化硅小球俘获过程横向和轴向运动的同步观测.该成像方法无需扫描和数据重构,具有实时快速等优点,在新型光束光镊、厚样品三维观测和成像等领域具有潜在的应用价值.     

Optical sectioning using single‐plane‐illumination Raman imaging

Confocal Raman imaging is widely used for optical sectioning of materials. However, for biological applications it often suffers from poor axial resolution, photodamage to the sample of interest, substrate interference, and long acquisition times. We have applied the principles of light sheet microscopy to Raman imaging and show for the first time that optically sectioned Raman images can be obtained in significantly lower acquisition times. Copyright © 2010 John Wiley & Sons, Ltd.     

Polarization difference image analysis with LC filter

Image analysis using polarizing methods allows removing the polarized light component from recorded images. This is known as polarization difference imaging (PDI). The use of liquid crystals (LC) in PDI was proposed in 2002. Modified LC unit with a properly oriented LC layer was proposed by the authors. The main parameters which characterize an imaging system, employing a circular LC filter, were determined and presented in previous papers. In this work, the basics of the circular LC filter construction and theory are presented. Two application configurations of PDI imaging systems are shown. Experimental results of image processing based on object’s polarization properties are discussed.     

Toluene laser-induced fluorescence for in-cylinder temperature imaging in internal combustion engines

A single-laser single-camera imaging technique was demonstrated for in-cylinder temperature distribution measurements in a direct-injection internal combustion engine. The single excitation wavelength two-color detection technique is based on toluene laser-induced fluorescence (LIF). Toluene-LIF emission spectra show a red-shift with increasing temperature. Temperature can thus be determined from the ratio of the signal measured in two separate wavelength ranges independent of the local tracer concentration, laser pulse energy, and the intensity distribution. An image doubling and filtering system is used for the simultaneous imaging of two wavelength ranges of toluene LIF onto the chip of a single camera upon excitation at 248 nm. The measurements were performed in a spark-ignition engine with homogeneous charge and yielded temperature images with a single-shot precision of approximately ±?6%.     

基于辅助光学系统的KB显微镜瞄准方法

 研究了利用辅助可见光系统精确瞄准KB显微镜物点的方法。设计了工作能点8 keV的周期多层膜KB显微镜系统,通过光线追迹和X射线成像实验,得到5 μm空间分辨率所对应的视场和景深,进而计算出诊断实验对应的指向和景深要求。基于KB系统的物像关系和精度要求,设计了辅助的可见光成像系统,实现了可见光系统与X射线KB系统间的等效瞄准,利用耦合好的系统进行了瞄准和X射线成像实验。实验结果表明:辅助光路可以实现±20 μm的垂轴面和±300 μm的轴向定位精度,满足KB显微镜的瞄准要求。