Perfect digital holographic imaging with high resolution using a submillimeter-dimension CCD sensor

In order to improve the resolution of digital holography with a common-dimension charge-coupled device (CCD) sensor, the point spread functions are briefly derived for the commonly used and practical post-magnification, pre-magnification, and image-plane digital holographic microscopic systems. The ultimate resolutions of these systems are analyzed and compared. The results show that the ultimate lateral resolution of pre-magnification digital holography is superior to that of post-magnification digital holography in the same conditions. We also demonstrate that the ultimate lateral resolution of image-plane digital holography has no correlation with the photosensitive dimension of the CCD sensor, and it is not significantly related to the pixel size of the sensor. Moreover, both the ultimate resolution and the imaging quality of image-plane digital holography are superior to that of pre- and post-magnification digital holographic microscopy. High-resolution imaging, whose resolution is close to the ultimate resolution of the microscope objective, can be achieved by image-plane digital holography even with a submillimeter-dimension sensor. This system, by which perfect imaging can be achieved, is optimal for commonly used digital holographic microscopy. Experimental results demonstrate the correctness of the theoretical analysis.     

基于单数码相机的三维视觉测量数据拼接方法

针对大型物体三维形貌视觉测量,提出了一种新的视觉测量三维数据拼接方法。以一台高分辨率数码相机作为全局测量设备,在测量过程中固定不动,并以数码相机坐标系作为全局坐标系。视觉传感器流动到不同位置对物体各子区域进行测量,获得局部坐标系下的三维数据。以一平面靶标为中介将视觉传感器在各位置的局部坐标系统一到全局坐标系下,从而将三维数据统一到全局坐标系下,完成三维拼接。该方法无需在被测物上贴标记,因此适用于任何材质的被测物,且消除了拼接累积误差。实验结果表明,该方法相对拼接误差为0.076%。以Venus石膏像为被测对象,视觉传感器对其三个局部区域进行测量,给出了局部测量结果及拼接结果。     

A fast integrated optical sensor of gaseous substances

We consider the design and operation of an absorption integrated optical chemical sensor, which provides control of the content of ammonia and other hazardous gaseous and liquid substances in the air. An integrated optical sensor based on a diffusion waveguide is studied. The advantage of measurement schemes in which an analog signal from the integrated-optical sensor is converted into a digital form to be processed is shown. The limiting sensitivity of such a waveguide-sensor cell istheoretically evaluated. Prospects of using such a type of integrated-optical sensors are discussed.     

彩色数码相机光强传递函数的场景曝光标定

由传感曲线的数学特征表明,有限项多项式完全可以满足传感器函数的拟合及其精度。通过定义相对光强和推导出与传感器函数等价的光强传递函数,建立了场景标定原理。仅改变曝光时间,保持相机的其它参数不变,建立了曝光标定原理。将两种标定原理相结合,形成了关于彩色数码相机光强传递函数的场景曝光标定方法,并对Olym-pus E-20p数码相机进行了标定。     

振动传感器智能化的研究与实现

在测控领域内,随着传感器技术和微处理器技术的发展,对传感器的精确度、可靠性要求越来越高,要求传感器具有一定的数据处理、自我检测、自我纠错能力,并且具有数据通信和扩展组网功能。为了满足这个要求,文中提出了一种基于CAN总线技术的振动传感器智能化方案,详细介绍了智能传感器节点硬件电路和固件程序设计的具体实现。对智能节点进行静态和动态测试,静态环境下传感器电压值输出为2.5V,上位机对数据处理后作图,符合实际要求;动态环境下,将传感器置于连续振动环境,数字量数据接收后经处理作图,与标准传感器波形图进行比较,满足设计要求。     

Heat-transfer regularities of the anemometric wire

Experimental heat-transfer data for a small-diameter hot wire have been obtained and generalized in a wide range of Reynolds numbers typical of hot-wire anemometry. The experiments were carried out using an IRVIS-TA5 digital hot-wire anemometer and standard critical nozzles used for regulating the flow in the test section of the Eiffel chamber in which the hot-wire sensor was installed. Approaches to carrying out hot-wire anemometric measurements without a labor-consuming calibration procedure for the hot-wire sensor are substantiated.     

数字、模拟无线混合网络视频节点设计

针对无线多媒体传感器网络广泛的应用前景和目前节点平台稀缺的情况,设计并研制了一种小型化的无线多媒体传感器网络节点。节点采用ADI公司的ADSP-BF561微处理器和Helicomm公司的基于Zigbee网络协议的无线收发模块IP-Link研制而成。在输入通道上可分别支持模拟图像传感器和数字图像传感器。输出通道具有多媒体传输通道和数据/命令传输通道,其中多媒体传输通道用于传输实时的模拟视频,数据/命令传输通道用于传输节点处理之后的有效数据以及接收来自上层网络的命令。     

Stereoscopic 3D visualization of particle fields reconstructed from digital inline holograms

Holography is a powerful tool as it codes information, e.g. on 3D positions in a particle field in a single 2D hologram. In digital holography, the holograms are recorded on a digital image sensor. It is a particular challenge to visualize a digital hologram's depth information, such that it can be understood intuitively while retaining the advantages of a numerical reconstruction. In this contribution it is suggested and demonstrated how a numerically constructed volume can be used to calculate stereoscopic views, which even in the case of non-diffuse illumination allow for an intuitive visualization of particles’ positions in 3D space.     

Technique for compensating excessive rigid body motion in nondestructive testing of large structures using shearography

A major limitation of speckle interferometry techniques including shearography is that the occurrence of rigid body motion produces a decorrelation of speckle patterns which destroys the fringe visibility. This paper demonstrates that digital shearography can tolerate much greater rigid body translation than a speckle size as predicted by the conventional speckle decorrelation theory. Excessive rigid body translation in digital shearography can be compensated by either translating the sensor/camera or digitally shifting one of the speckle patterns.     

Astigmatic coherence sensor for digital imaging

We present a novel sensor that measures the entire spatial coherence function within an aperture by use of a variable astigmatic lens. This sensor permits digital capture and processing of partially coherent fields. We demonstrate the sensor by sampling and computing the coherent modes of a three-dimensional incoherent source.     

基于光相干外差检测的布里渊散射DOFS的研究

对布里渊散射分布式光纤传感器(DOFS)检测原理进行了分析, 针对布里渊散射光信号的特点, 应用光相干和外差技术来检测布里渊散射光信号. 具体采用微波电光调制产生频率可调的参考光, 和布里渊散射光进行相干检测, 根据布里渊频移特性取出布里渊散射光信号, 从而得到分布式传感信号. 分别实现了25 km光纤的分布式温度和应变传感, 达到3℃的温度分辨率、100 με的应变分辨率和10 m的空间分辨率.     

数字相机传感器光谱灵敏度的测量

为了测量数字相机传感器的光谱灵敏度,提出了一种数字图像测量方法。在自然日光下,用被测相机采集一副标准色卡的图像,在对图像进行均匀性和线性校正后,从标准色卡图像各色块的相机响应中计算出光谱灵敏度,并在不同的照明光源下,用成像方法验证数字图像测量方法与传统的单色仪测量方法的结果,比较了两种测量方法的优缺点和精确度。实验结果表明,两种测量方法均能获得较高精度的光谱灵敏度。     

多测点智能温度传感器设计

针对广泛应用的温度检测,设计了一种多测点智能温度传感器。该智能温度传感器将多个常规温度传感元件、信号调理电路、带数字总线接口的微处理器连接起来,利用三维单片智能传感器结构集成在一块硅基片上,实现了三维集成多层结构。同时智能温度传感器利用信号幅度、变化趋势、多测点冗余故障判决和传感信息融合方法,在实现传感故障诊断的同时提高检测准确度。     

集成聚焦式测头的纳米测量机用于台阶高度标准的评价

利用集成聚焦式测头的纳米测量机实现了高精度的台阶高度标准评价,该系统的测量范围可以达到25mm×25mm×5mm.描述了纳米测量机的工作原理,通过内嵌激光干涉仪和角度传感器的实时测量与反馈,实现高精度定位与扫描.聚焦式测头只作为零点传感器,与3个激光轴交于一点,避免了阿贝误差影响.通过将聚焦式测头的输出信号引入到纳米测量机的数字信号控制器中,实现定位系统的辅助测量,减小了聚焦式测头的非线性对测量结果的影响.根据ISO 5436-1:2000的评价方法对经过标定的台阶高度进行评价,14次测量的均方根(RMS)偏差为0.237nm.     

基于CMOS图像传感器的可见光遥感相机原型系统设计

遥感器是遥感技术应用的基础设备,它决定了遥感系统的成像质量。介绍了光电传感器在可见光遥感中的应用,阐述了光电遥感器的结构与关键技术,提出了CMOS数字传感器在遥感领域应用中所具有的优势,设计并实现了基于CMOS传感器的光电成像原型系统。结果表明,遥感相机的图像获取、数据存储的基本功能为CMOS在可见光遥感应用中的相关问题提供了研究平台和技术储备。     

杨氏模量测量的研究性与综合性实验设计

通过测量悬臂梁自由阻尼振动频率等参数来计算梁状材料的杨氏模量.实验通过精心设计,涉及并运用了力传感器、惠斯通电桥、数字存储示波器、计算机接口、快速傅里叶变换和LabVIEW虚拟仪器等知识和内容.     

半导体光纤温度传感器

本文利用半导体材料的吸收光谱随温度变化的特性,研制了数字显示光纤测温仪。经过反复试验,该仪器在-20°～200℃温度范围内的测温精度为±2℃。     

面向实时视觉芯片的高速CMOS图像传感器

提出了一种面向实时视觉芯片的高速CMOS图像传感器.该高速图像传感器主要包括CMOS像素单元阵列、相关双采样(CDS)阵列、可编程增益放大(PGA)阵列、单次比较模数转换(ADC)阵列和控制模块.该传感器集成了光信号采集和行并行信号处理等功能,以大于1000 frame/s的速度输出数字信号或数字图像,同时实现了行并行...     

基于编码标志点的数码相机三维测量与重构

介绍了利用数码相机作为图像传感器,在物体表面设置编码标志点,通过对编码标志点进行识别和检测,从而确定标志点的空间位置,实现了对物体表面某些特定点三维信息的无接触检测。介绍了其中的关键技术,如标志点的设计与检测、基础矩阵的求解、数码相机参数的标定以及内外参数的捆绑调整等,给出了检测实例并进行了精度验证。实验证明,该方法结构简单,成本低廉,数据采集快,移动方便,检测范围大,可满足三维物体特别是大面积物体空间检测的需求。     

Instantaneous velocity measurement of dynamic deformation by digital holographic interferometry

A novel method for the instantaneous velocity measurement of dynamic deformation by digital holographic interferometry is proposed. During dynamic deformation, a series of digital holograms is recorded by a high-speed camera. At each pixel of the phase difference maps, phase and amplitude information are combined as complex phasor (CP). Each pixel can be then considered as an independent sensor and a sequence of complex phasors of such a sensor is analyzed by short time Fourier transform (STFT) along the time axis. A fast iterative algorithm is developed for the computation of instantaneous velocity. The displacement of each pixel can also be obtained by integration of the instantaneous velocity over time and phase unwrapping process is thus avoided. The performance of the proposed CP method is compared experimentally with the commonly used digital phase subtraction method.