超声波多点定位

介绍了利用超声波对多个物体进行定位的装置及方法,利用2个超声波收发传感器接收每个物体的反射波,并通过一定的算法计算出每个物体的位置.该装置可对二维空间内多个物体进行定位,并可对其测速、跟踪,甚至测出物体轮廓.     

Visualization of two-dimensional flows by a Liquid (Soap) Film Tunnel

Experimentally produced two-dimensional flows have become possible in recent years due to the invention of Liquid Film Tunnel (LFT) in 1987 by Gharib and Derango. This simple, inexpensive, yet powerful device, which we have improved extensively over the last decade, can generate a variety of flows. Liquid (soap) films can be visualized through light interference effects produced by small variations in the film thickness. Flow-disturbing objects such as cylinders, wedges, and air bubbles create these variations. Monochromatic visualization of these thickness variations will render phenomenally accurate graphic information about the flow patterns thus produced. Under a polychromatic light, these interference effects can be spectacular, due to reflection of different colors by different isothickness regions.     

Design method of reusable reciprocal invisibility and phantom device

Reusable reciprocal invisibility and phantom device is proposed and designed based on multi-folded transformation optics and equivalent components. In comparison with the reported reciprocal invisibility cloaks, the material parameters of the device presented here are homogeneous, and the hiding of the target object does not require any "anti-object" at all, which dramatically breaks through the limitations of the "anti-object" design in previous reciprocal cloak design. Perfectly illusion effect is also found by reasonably setting the material parameters of the restored medium of the device, which can be used to confuse detection radars while hiding target objects. Last but not least, the proposed device has an open structure, which enables the target object enclosed by the device to perform material exchange and simplex transfer of information with the outside world through open channels. In other words, the proposed device has a reusable function, enabling stealth or phantom of new target objects without changing any parameters of the device.     

Near-field scanner for moving molecules

We have fabricated using electron beam nanolithography a fixed slit near-field optical scanning device which uses near-field fluorimetry to achieve 200 nm spatial resolution of objects moving over the slits. We explore the basic physics of operating narrow slits in the waveguide cutoff mode and present data from the passage of extended double-stranded DNA molecules passing over the slits as a first example of how this device can be used to do ultrahigh spatial resolution mapping of long polymers.     

Possible evidence for the observation of noncompact (nonbaryonic) gravitational microlenses (“neutralino stars”)

The microlensing of distant stars by noncompact objects such as neutralino stars is considered. Recently, Gurevich and Zybin considered the objects as microlenses. Using a nonsingular density distribution, we analyze microlensing by noncompact objects. We obtain analytic solutions to the gravitational-lens equation and an analytic expression for the amplification factor of the gravitational lens. We show that, on the basis of a model of microlensing by noncompact objects, it is possible to interpret microlensing-event candidates having two typical maxima of light curves which are usually interpreted as binary microlenses.     

双缝光幕靶设计

针对动力源火工品速度测试，设计了一种双缝光幕靶，实现对低速运动的火工品零件测速。与常规的单缝光幕靶不同，文中设计的双缝光幕靶将2个发射和接收装置融进一个单体结构，形成2个光幕。2台双缝光幕靶安装在同一个带有滑轨的固定架上，靶距可以任意调节。设计的双缝光幕靶可以替代传统的铜片测速方法，有效地提高了测量精度和实现了测量自动化。经过实弹射击和火工品试验验证，设计的双缝光幕靶测试系统可靠，测试数据准确。     

基于亚微米尺度干涉阵列的超小型高分辨光谱仪(英文)

We present an ultra compact and high resolution free space optical spectrometer and demonstrate it by using FDTD simulations. The miniature interferometer-based speetrometer is a series of submicron phase objects on a polymethyl methacrylate（PMMA） film with a CCD as the detector. The speetrum is obtained by solving a system of simultaneous linear equations. The Tikhonov regularization method is used to achieve a resolution at the picometer level. Compared with conventional speetrometers, the proposed device is low-cost and easy to fabricate due to its simple structure. Furthermore, its compact feature renders the device ideal for miniaturization and integration as the systems in microfluidics architectures and lab-on-chip designs.     

Single-pixel polarimetric imaging spectrometer by compressive sensing

We present an optical system that performs polarimetric spectral imaging with a detector with no spatial resolution. This fact is possible by applying the theory of compressive sampling to the data acquired by a sensor composed of an analyzer followed by a commercial fiber spectrometer. The key element in the measurement process is a digital micromirror device, which sequentially generates a set of intensity light patterns to sample the object image. For different configurations of the analyzer, we obtain polarimetric images that provide information about the spatial distribution of light polarization at several spectral channels. Experimental results for colorful objects are presented in a spectral range that covers the visible spectrum and a part of the NIR range. The performance of the proposed technique is discussed in detail, and further improvements are suggested.     

基于扫描相机的激光三维成像研究

随着条纹管器件技术的发展,条纹管作为瞬态光学器件的应用不再局限于高速摄影和光谱学研究领域。建立以单狭缝条纹管为核心器件的扫描相机激光成像系统,对目标进行推扫成像,获得原始条纹图像,并进行特征数据提取和三维重建。理论计算出的两目标的距离差与实际距离差较接近,从而验证采用该系统作激光雷达成像的可行性。实验结果表明,基于扫描相机激光雷达具有高分辨率,具有较好的应用前景。     

Two-dimensional imaging with a single-sided NMR probe

A new low field unilateral NMR sensor equipped with a two-dimensional gradient coil system was built. A new NMR-MOUSE concept using a simple bar magnet instead of the classical U-shaped geometry was used to produce magnetic field profiles comparatively homogeneous in extended lateral planes defining a suitable field of view for 2D spatial localization. Slice selection along the depth direction is obtained by means of the highly constant static magnetic field gradient produced by this magnet geometry. Implementing a two-dimensional phase-encoding imaging method 2D cross sections of objects were obtained with high spatial resolution. By retuning the probe it was possible to change the depth of the selected slice obtaining a 3D imaging method. The details of the construction of the new device are presented together with imaging tests to show the quality of space encoding.     

Acoustical holography and its applications

A device capable of producing images of objects immersed in opaque media could find application in such areas as engineering inspection, underwater viewing, and medical diagnosis. The results of some experiments in acoustical holography as a viewing system are presented here, together with an assessment of the problems which must be solved before the technique can find useful application.     

Missing data in image and signal processing: The case of binary objects

I investigated which portions of the Fourier transform of binary signals, images and three-dimensional objects are necessary to correctly identify an object in the presence of noise. This is practically possible for very small binary data sets since the total number of possible objects is then very limited. There are for example 512 different binary images with 9 pixels. It is easy to see that this number soon becomes impractically large for bigger images or if one allows more than two possible pixel values. It turns out that even in the presence of large amounts of noise a relatively small portion of the Fourier transform is essential for deciding which of all possible binary objects the Fourier transform belongs to. These ‘decision experiments’ can be used as a standard for how well algorithms for retrieval of missing Fourier components perform. In another set of computer experiments I investigate the possibility of retrieving various missing Fourier components algorithmically. The main finding of this second set of computer experiments is that the simple retrieval algorithm (a limited form of ‘projection onto convex sets’) used falls very much short of what one might expect from the ‘decision experiments’.I conclude with a discussion what this discrepancy might be due to and some suggestions how to improve the performance of retrieval algorithms for binary objects.     

超声波多普勒实验仪

基于多普勒效应原理,分别测得波源的频率和发生相对运动时观测到的频率即可分析出物体相对运动的速度.实验仪以单片机为测控系统核心实现超声波多普勒效应演示实验及速度测量并提供了具体的设计方案与实验结果.同时单片机赋予了仪器以软件为核心的技术特点,具有重塑性与可扩展性.     

Colour encoded aperture masks used for incoherent filtering of images

A device is described which is capable of real-time linear filtering of incoherently illuminated objects. It uses colour encoded aperture masks to multiplex the filtering channel.     

对比式离心现象实验装置

为了弥补现行教科书中,离心运动的演示实验装置及离心现象产生实质的知识呈现不足,设计了符合学生认知规律的离心实验装置.该装置通过对比2个物体在相同的角速度下产生相反的运动状态,说明物体做离心运动,不是由角速度产生,而是只有合外为突然消失或是合外力不足以提供向心力时,才能产生离心运动.     

Molecular-scale electronics

Molecular electronics is envisioned as a promising candidate for the nanoelectronics of the future. More than a possible answer to the ultimate miniaturization problem in nanoelectronics, molecular electronics is foreseen as a possible and reasonable way to assemble a large numbers of nanoscale objects (molecules, nanoparticles, nanotubes and nanowires) to form new devices and circuit architectures. It is also an interesting approach to significantly reduce the fabrication costs, as well as the energetical costs of computation, compared to usual semiconductor technologies. Moreover, molecular electronics is a field with a large spectrum of investigations: from quantum objects for testing new paradigms, to hybrid molecular-silicon CMOS devices. To cite this article: D. Vuillaume, C. R. Physique 9 (2008).     

激光全息无损检测实验

本介绍了利用激光全息干涉计量对物体进行检测技术。并给出了实验装置和对物进行检测的图片。     

基于银膜孔阵列超强透射效应的相敏表面等离子体共振传感器的仿真研究(英文)

We present an ultra compact and high resolution free space optical spectrometer and demonstrate it by using FDTD simulations. The miniature interferometer-based spectrometer is a series of submicron phase objects on a polymethyl methacrylate(PMMA) film with a CCD as the detector. The spectrum is obtained by solving a system of simultaneous linear equations. The Tikhonov regularization method is used to achieve a resolution at the picometer level. Compared with conventional spectrometers, the proposed device...     

基于F-W暗物质模型的暗物质探测仪的设计思路

按F-W暗物质模型,暗物质之间有相互作用,能够形成暗天体.飞临地球的小暗天体会对已知物体有微引力效应.由此提出了暗物质小天体探测仪的设计原理,定量计算了飞临地球的暗天体通过探测仪时导致的力矩变化.     

位相物体激光全息二次曝光法无损检测

为借助激光全息进行无损检测，获得位相物体的信息，对位相物体激光全息二次曝光法无损检测进行了研究，指出一般的二次曝光法测位相物体典型光路的缺点，提出了物光波2次通过样品的改进方案。利用此方案对一些位相物体(如普通玻璃和有机玻璃)作了无损检测实验，得到了较满意的实验结果。与普通检测方法相比，该方法具有精度高、结果直接可靠、不损伤物体等诸多优点。对改进方案稍作改动，即可用于塑料制品和玻璃制品生产线对加工产品进行在线产品质量监控。