共查询到20条相似文献,搜索用时 0 毫秒
1.
2.
Based on the extended Huygens–Fresnel integral and the theory of coherence of light field, we have investigated the correlated imaging by using the transverse normalized second-order intensity fluctuation correlation function with partially coherent light radiation. The imaging for a reflected object with relative long distance is determined by the feature of speckle-to-speckle correlation. By using the correlation function, we study the effects of imaging distance, the sizes of object lens and reference lens, the source’s transverse coherent width and its transverse size on the quality of correlated imaging. Numerical results show that the parameters of imaging system and the properties of partially coherent light source have significant influences on the imaging resolution and visibility. For an object lens with large enough diameter, the resolution is determined by the transverse coherent width of light source. On the contrary, it depends on the aperture of object lens. The magnification of the system depends only on the propagation distance. This speckle-to-speckle correlated imaging with unbalanced arms have potential applications in remote sensing due to its unique features. 相似文献
3.
讨论了机载激光荧光遥感监测系统的空间分辨率及探测速度与搭载飞机扫描装置及束有关参数之间的关系,导出了相应的数学表达式。结果表明,增大激光脉冲重复率可以在不影响系统其他性能的情况下有效提高其空间辨率、而对多数参数的选取则位综合考虑它们对系统不同特性的影响。 相似文献
4.
AbstractAccuracy, flexibility and cost effectiveness are advantages of using digitized aerial photographs as a data source for remote sensing studies of the environment, such as forests. However, the relationship between the resolution of digital images and the aerial photographs from which they were derived must be addressed to ensure valid application using the environmental data. This communication considers issues that affect the information content of environmental data through the spatial resolution of photographs and digitized images, and suggests how users can optimize the spatial resolution of the latter by selecting an appropriate scanning aperture. An optimal scanning aperture can be chosen by considering the combination of the resolving power of the camera system, the scale of the original photograph and the desired pixel size of the digital image. Optimizing spatial resolution while scanning will maximize the spatial information obtained from the original photographs without generating unnecessarily large file sizes. The authors make several recommendations for the digitization of aerial photographs for environmental applications, such as analyses of forests. 相似文献
5.
In this paper a survey is given of the application of high resolution electron microscopy and selected area electron diffraction
to the study of long range ordered alloys. The characteristic features of the diffraction effects and of the imaging of ordered
alloys are discussed. Group theoretical considerations allow prediction of microtexture of such alloys.
A number of simple alloy structures are imaged and it is shown, by means of simulated images, that under suitable diffraction
conditions the columns of minority atoms are represented as bright dots. The columns of majority atoms are only visible at
very small thicknesses. Subsequently a number of one- and two-dimensional long period superstructures derived from these simple
structures are analysed, using high resolution micrographs. Finally the observed microtexture of the same alloy superstructures
is compared with the predictions of group theory. Strongly non-conservative antiphase boundaries are found to dissociate inapb’s which are as close to conservative as is compatible with thefcc lattice. 相似文献
6.
7.
8.
9.
本文介绍了利用模糊逻辑控制理论提高B型超声图像横向分辨力的方法,文章中介绍了变孔径技术,电子聚焦时原理及动态实时聚焦。 相似文献
10.
针对现有斜视多子阵合成孔径声呐成像算法忽略了"非停走停"假设的孔径依赖性和阵元依赖性,导致中等斜视时成像效果差的问题,提出了一种基于级数反演方法(Method of Series Reversion, MSR)的中等斜视多子阵合成孔径声呐距离多普勒算法(Range Doppler Algorithm, RDA)。首先,为了解决"非停走停"假设孔径依赖的问题,直接对精确距离史在波束中心处进行泰勒级数展开,得到近似距离史,并借用MSR求得近似距离史对应窄带回波信号的二维谱解析解。然后,为了解决阵元依赖的问题,使用基于MSR的RDA分别对每个子阵单独成像,再通过将每个子阵的成像结果进行相干叠加的方式消除单个子阵欠采样带来的混叠现象,得到完整的成像结果。最后,通过与现有算法的仿真对比实验,验证了该算法的有效性。 相似文献
11.
为了从高分辨率遥感影像中获取详细的地表地物信息,为城市规划、环境监测以及灾情分析提供可靠的数据,进行了高分辨率遥感影像的检索研究,包括对图像的特征提取和图像之间相似度的描述。为了提高图像检索精度,运用了采用稀疏编码(Sc)的空间塔式匹配(Sc SPM)技术和重排序(Reranking)技术,提出了基于Sc SPM结合Reranking(ScSPM-Reranking)的遥感高分辨率影像的检索方法。该方法首先使用Sc SPM提取空间场景的特征,然后结合这些特征使用cityblock距离进行初步检索,最后对初步检索的结果进行Reranking排序,获得高精度的检索结果。同其他检索方法进行了对比实验,实验结果证明,该方法具有较高的检索精度。 相似文献
12.
13.
14.
15.
In this paper we introduce first the concept of quality manufacturability (QM), and second a new methodology that focuses exclusively on evaluating a design from a quality perspective. We label this new approach as Design for Quality Manufacturability (or DFQM). The QM of a design is defined as the likelihood that defects will occur during its manufacture. Some designs are more likely than others to have a lower production yield rate. The reason for this is that in any production facility there is an inherent defect occurrence process. This relationship between the defect occurrence process and the design is the basis for QM. DFQM enables product designers to evaluate and improve the QM of a design before prototype production. The key elements of DFQM are classes of defects, specific defects, influencing factors, factor variables, and error catalyst. A standard nomenclature for describing the specific defects and measuring the associated influencing factors is presented. The output of the DFQM method is the QM-Index matrix, which indicates the quality manufacturability of each part in the assembly, in terms of each class of defects. The concept of error catalysts and the derivation of the QM-Index matrix are presented. An illustrative example is included. The DFQM method is presently limited to assembly processes. 相似文献
16.
17.
D. Burdette D. Albani E. Chesi N.H. Clinthorne E. Cochran K. Honscheid S.S. Huh H. Kagan M. Knopp C. Lacasta M. Mikuz P. Schmalbrock A. Studen P. Weilhammer 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2009,609(2-3):263-271
Very high resolution images can be achieved in small animal PET systems utilizing solid state silicon pad detectors. As these systems approach sub-millimeter resolutions, the range of the positron is becoming the dominant contribution to image blur. The size of the positron range effect depends on the initial positron energy and hence the radioactive tracer used. For higher energy positron emitters, such as and , which are gaining importance in small animal studies, the width of the annihilation point distribution dominates the spatial resolution. This positron range effect can be reduced by embedding the field of view of the PET scanner in a strong magnetic field. In order to confirm this effect experimentally, we developed a high resolution PET instrument based on silicon pad detectors that can operate in a 7 T magnetic field. In this paper, we describe the instrument and present initial results of a study of the effects of magnetic fields up to 7 T on PET image resolution for and point sources. 相似文献
18.
激光多普勒测速仪标定系统不确定度研究的自动测量设计 总被引:1,自引:1,他引:1
文章讨论激光多普勒测速仪标定系统不确定度研究中的自动测量原理与实现方法 ,给出了实现自动测量的设计思想和程序框图 .实验表明该程序设计是有效的 ,它可极大地提高系统不确定度研究的效率 相似文献
19.