共查询到19条相似文献,搜索用时 390 毫秒
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三维控制场是影响数字近景摄影测量技术现场应用效能的关键因素之一。提出了一种新颖的可用于数字近景摄影测量的三维控制场实现方法;研制了一套可应用于地下工程围岩变形监测的便携式精密三维控制场系统装置,系统可根据被测目标实际情况动态配置控制场各控制点物方坐标,从而实现控制场网型结构优化,具有小型化、便携化、快速化以及原位化等优点;对控制场精度影响因素及对应抑制措施进行了分析;基于该装置构建了数字近景摄影测量系统并进行了相关应用性实验,实验结果证明了该三维控制场完全满足地下工程围岩变形监测的应用需求。 相似文献
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光学3D坐标测量技术研究 总被引:4,自引:0,他引:4
研究了光学坐标测量系统三维精密视觉测量方法,对其核心技术:数字成像器件模型及标定方法、辅助靶标技术以及高精度亚象素图像处理算法进行了深入的讨论,并提出了详细的解决方法.经实验证明,这些方法切实可行,达到了所要求的精度,从而为光学坐标测量系统的设计提供了可靠依据. 相似文献
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目的:探讨多基线数字近景摄影测量技术在口腔颜面部三维成像和测量中的应用。方法:应用普通数码相机对口腔颜面部进行拍摄并获得多幅重叠无序的照片,采用多基线数字近景摄影系统对照片进行处理。结果:对颜面部组织长度及宽度测量上与传统手工测量方法相比无统计学差异(P0.05)。结论:多基线数字近景摄影测量技术操作简单、测量准确、对设备要求低,可用于口腔颜面部三维成像的测量中。 相似文献
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随着工业的快速发展,对数字近景工业摄影测量技术提出了更高的要求。文章首先对数字近景工业测量关键技术进行分析研究,包括单像机三坐标测量的新方法、像机的自标定算法,其次分析数字近景工业摄影测量关键技术的应用。 相似文献
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正您可能知道数字放映机不宜在高温下工作,但不一定知道它也不宜在低温下工作,那为什么呢?实际上这主要是数字放映机光引擎里成像器件DMD芯片的工作要求。因为DMD是个极为精密的、高集成度的数字微镜器件,是由极高精度受控的微镜阵列组成,每个像素都是一粒带精密连接的小镜子单元,工作时不断翻转,来反射光线从而形成影像。那到底为什么不宜在太低的温度下工作呢? 相似文献
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Abstract: Optical methods of contouring that utilise image recordings by cameras are based on a fundamental discipline, projective geometry. The 3‐D world is projected in 2‐D utilising a camera modelled in the technical literature by the pinhole camera. To get back 3‐D information, the fundamental property measured is parallax. Parallax is a vector resulting from the difference of the projective coordinates of a point in space when projected onto a plane from two different points. The oldest method used for measuring parallax is photogrammetry. It is assumed to be the most precise technique, with the capability of obtaining 10?5 of the largest dimension of the measured object. This study summarises the state‐of‐the‐art methods based on projecting a spatial carrier. Starting with the concept of moiré as a form of photogrammetry, the different optical techniques for parallax determination are discussed. Although the moiré method has reached 1 μm accuracy in laboratory work, a question remains: can moiré become a standardised contouring technique yielding 10?6 m accuracy? This study is devoted to the analysis of high accuracy contour measurements, through both theoretical derivations and experimental verifications. 相似文献
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Awatsuji Y Tahara T Kaneko A Koyama T Nishio K Ura S Kubota T Matoba O 《Applied optics》2008,47(19):D183-D189
We propose a parallel two-step phase-shifting digital holography technique capable of instantaneous measurement of three-dimensional objects, with a view toward measurement of dynamically moving objects. The technique is based on phase-shifting interferometry. The proposed technique carries out the two-step phase-shifting method at one time and can be optically implemented by using a phase-shifting array device located in the reference beam. The array device has a periodic two-step phase distribution, and its configuration is simplified compared with that required for three-step and four-step parallel phase-shifting digital holographies. Therefore the optical system of the proposed technique is more suitable for the realization of a parallel phase-shifting digital holography system. We conduct both a numerical simulation and a preliminary experiment in the proposed technique. The results of the simulation and the experiment agree well with those of sequential phase-shifting digital holography, and results are superior to those obtained by conventional digital holography using the Fresnel transform alone. Thus the effectiveness of the proposed technique is verified. 相似文献
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A new acoustic grating fringe projector (AGFP) was developed for high-speed and high-precision 3D measurement. A new acoustic grating fringe projection theory is also proposed to describe the optical system. The AGFP instrument can adjust the spatial phase and period of fringes with unprecedented speed and accuracy. Using rf power proportional-integral-derivative (PID) control and CCD synchronous control, we obtain fringes with fine sinusoidal characteristics and realize high-speed acquisition of image data. Using the device, we obtained a precise phase map for a 3D profile. In addition, the AGFP can work in running fringe mode, which could be applied in other measurement fields. 相似文献
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A virtually imaged phased array (VIPA) installed optical interferometer has been expanded to the two-dimensional (2D) tomography from the previous one-dimensional single-shot imaging technique with keeping the resolution and the measurement range. A single-shot measurement has been realized by a spatial phase modulator installed in the optical interferometer and tracing the delay time to pixel numbers on a 2D charge-coupled device (CCD) image sensor. The flexibility of the sample position was experimentally confirmed to be >25 mm, in relation to the VIPA coherency, for which the number of the interference order was confirmed to be 35. As a demonstration, a surface profile of stacked gauge blocks was observed. The repeatability of the surface position was 5?μm for the surface profilometry. In addition, a multilayer structure was observed using a glass plate. The experimental resolution was 53?μm when the amplified spontaneous emission light generated by the optical fiber amplifier was used for the light source. The single-shot measurement was confirmed by the 2D-CCD at a frame rate of 30 frames per second (FPS), and it provided evidence that the 2D scanless profilometry was successfully achieved using the VIPA optical device. 相似文献
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Bleichner H. Nordlander E. Rosling M. Berg S. 《IEEE transactions on instrumentation and measurement》1990,39(3):473-478
The measurement of two-dimensional (2-D) excess-carrier distribution in a gate GTO by a time-resolved infrared-absorption technique is discussed. The optical scanning system employs a wide memory digital oscilloscope for data acquisition and a computer system for control, data processing, and display. Maps of the carrier distribution in the active GTO device are produced under steady-state conditions as well as during turn-on and turn-off operation. The maps are presented as three-dimensional (3-D) views produced from 2-D measurements 相似文献
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We propose parallel three-step phase-shifting digital holography as a technique capable of noiseless instantaneous measurement of three-dimensional objects based on phase-shifting interferometry. The proposed digital holography carries out three-step phase shifting at the same time by using a phase-shifting array device located in the reference beam. The array device has a periodic three-step phase distribution, and its configuration is simplified compared with that required for conventional parallel phase-shifting digital holography. Therefore the optical system of the proposed parallel phase-shifting digital holography is more suitable for the realization of the proposed holography. We conduct both a numerical simulation and a preliminary experiment. The results of the simulation and experiment agree well with those of the conventional phase-shifting method and are superior to the results obtained by conventional digital holography by using the Fresnel transform alone. Thus the effectiveness of the proposed technique is verified. 相似文献
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Dr. Jaroslaw Iwicki Sophie Gottschall Dr. Michael Flämmich Dr. Ute Bergner 《真空研究与实践》2016,28(5):46-49
Vacuum Measurement over the Course of Time — From Torricelli to bakeable digital wide‐range sensors for measurement from 103 to 10‐12 mbar Since the first vacuum measurement in the middle of the 17th century, various methods have been developed to measure total vacuum pressures. After establishing the kinetic theory of gases in the late 19th century, the development of different indirect measurement methods started. Hereby, the lower detection limit — located in the fine vacuum range for direct methods such as mercury tubes — has been continuously shifted down to the ultrahigh vacuum range. The combination of different measuring principles in wide‐range sensors soon allowed the measurement over extended pressure ranges — with just one device. Latest developments have yielded to the creation of a new generation of vacuum measurement: passive bakeable wide‐range sensors. Consisting of optimized ionization‐sensors and a novel integration of a digital Pirani principle, they are the first vacuum sensors for precise total pressure measurement over 15 decades — from atmosphere down to the ultra‐high vacuum (10+3 to 10‐12 mbar). 相似文献