主动离焦三维测量的调制度全局计算方法

提出了离焦三维测量的全局计算方法。通过向物体投射正弦光栅,使物体上任一点的光分布在光栅频率(局域傅里叶变换)处的光强度等于该处的调制度,利用拍摄物体的两幅离焦像的调制度之比,得到了物体的深度分布。不但消除了过去主动离焦三维测量采用局域傅里叶变换带来的测量误差,同时计算程序简单、速度快,具有较好的实用性。     

The influence of structure depth on image blurring of micrometres-thick specimens in MeV transmission electron imaging

This study investigates the influence of structure depth on image blurring of micrometres-thick films by experiment and simulation with a conventional transmission electron microscope (TEM). First, ultra-high-voltage electron microscope (ultra-HVEM) images of nanometer gold particles embedded in thick epoxy-resin films were acquired in the experiment and compared with simulated images. Then, variations of image blurring of gold particles at different depths were evaluated by calculating the particle diameter. The results showed that with a decrease in depth, image blurring increased. This depth-related property was more apparent for thicker specimens. Fortunately, larger particle depth involves less image blurring, even for a 10-μm-thick epoxy-resin film. The quality dependence on depth of a 3D reconstruction of particle structures in thick specimens was revealed by electron tomography. The evolution of image blurring with structure depth is determined mainly by multiple elastic scattering effects. Thick specimens of heavier materials produced more blurring due to a larger lateral spread of electrons after scattering from the structure. Nevertheless, increasing electron energy to 2 MeV can reduce blurring and produce an acceptable image quality for thick specimens in the TEM.     

CMOS传感器感光范围测定系统及其可编程接口的实现

介绍了一种实用的CMOS传感器感光范围测定系统。利用积分球作标准光源,并用逻辑分析仪作数字输出信号的分析统计,测出CMOS传感器光照度接收曲线。在此基础上提出了一种基于可编程接口(FPGA)芯片控制的CMOS传感器自动调光技术。利用FPGA控制CMOS传感器的电子快门,以此来控制其光照度,达到自动调光的目的。由于FPGA是在线可编程器件,具有电路简单,实时性好,适应性强等特点,并能与后期的图像处理有机结合,所以简化了整个系统的设计。     

有源声呐中的改进加权自适应高分辨距离估计方法

为提高有源声呐对目标回波亮点的距离分辨能力,提出了一种改进加权自适应高分辨距离估计方法,所提方法功率谱中的权值矩阵可采用3种形式:第1个元素为残差平方和其余为0的对角阵、单位阵、残差平方和构成对角阵,采用不同参考子带高阶线性预测的调和平均构造功率谱表达式,避免了距离维自适应方法功率谱中的低阶线性预测。通过数值仿真和水池试验对所提方法与距离维自适应方法进行了比较研究,结果表明所提方法在接近的计算量下获得较优的距离分辨能力。     

A parallel-multipoint fiber-optic temperature sensor based on Fresnel reflection

A parallel-multipoint fiber-optic temperature sensor for monitoring ambient temperature with a measured temperature resolution of approximately 0.03 °C is presented. The sensor relies on the temperature-dependent Fresnel reflection from each interface between a sensing fiber tip and a thermo-optic medium. An arrayed waveguide grating is used to achieve wavelength-division multiplexed-multipoint sensing. Applying the relative-intensity technique, the errors resulting from fluctuation of the light source and other influences of the environment are eliminated, and the stability for long time measurement can be improved.     

一种基于光学干涉原理的图像分割方法

 介绍了基于光学干涉原理的图像分割理论算法。在计算机上模拟一个均匀相干光源、一个滤波器和一个接收屏。选择强度 相位的转换曲线，将输入图像的强度信息转化成伪相位信息，并显示在滤波器上。利用光源照明滤波器上的相位图，在接收屏上得到其干涉条纹。再通过选择阈值对干涉图进行分割得到二值图，从而实现输入图像的边缘分割。计算结果表明，该方法得到的图像轮廓，与Sobel 算子效果相当。与实验结果对比分析可得，改善硬件并实现良好的分割效果的关键在于：控制光源的相干长度，或增大液晶的点阵间隔，并利用CCD相机和计算机相连，对干涉图进行二值化。     

A robust level set method based on local statistical information for noisy image segmentation

The paper presents an improved local region-based active contour model for image segmentation, which is robust to noise. A data fitting energy functional is defined in terms of curves and the energy terms which are based on the differences between the local average intensity and the global intensity means. Then the energy is incorporated into a level set variational formulation, from which a curve evolution equation is derived for energy minimization. And then the level set function is regularized by Gaussian filter to keep smooth and eliminate the re-initialization. By using the local statistical information, the proposed model can handle with noisy images. The proposed model is first presented as a two-phase level set formulation and then extended to a multi-phase one. Experimental results show desirable performances of the proposed model for both noisy synthetic and real images, especially with high level noise.     

一种基于简正波模态消频散变换的声源距离深度估计方法

针对浅海环境中传播的低频宽带水声脉冲信号,基于简正波水平波数差和波导不变量之间的关系,本文提出了一种利用距离-频散参数二维平面聚焦测距与匹配模态能量定深的目标声源定位方法.首先,通过将由频散参数和波导不变量表示的前几阶模态相速度与由环境模型计算的相速度进行对比分析,从而估计出前几阶模态的频散参数和环境的波导不变量.其次,利用估计出的频散参数值和波导不变量对接收信号进行消频散变换处理,只有当接收信号的距离参数等于目标声源距离时,各号简正波的幅度均达到最大值,在距离-频散参数二维平面上,出现声压聚焦的现象,利用此现象可以估计目标声源的距离.不仅如此,消频散变换后的接收信号,前几阶模态在时域上明显地分离开来,可以准确地估计出前几阶模态的能量,采用多模态能量匹配的方式,可以估计出目标声源的深度.最后,通过对仿真和冬季获得的气枪信号数据处理结果验证了本文方法的有效性.     

一种应用距离选通成像技术的微光望远镜

利用红外波长的激光对微光系统进行辅助照明,改善目标区域的环境照度和对比度,使目标从视场中凸显出来,提高微光系统的探测距离,改善观察效果。采用距离选通技术,合理匹配激光脉冲与选通像增强器的工作时序,屏蔽目标前后非目标反射光以及来自大气中悬浮微粒产生的杂散光干扰,解决同轴照明后向散射问题,达到只观察选定距离内目标的目的。通过微光选通望远镜的工程实践,将激光距离选通技术成功地运用于微光探测领域中,在无月星光,照度为110-3lx,大气能见度为10 km条件下,对中型坦克或卡车侧面目标的识别距离可达到1 400 m。     

基于马赫-曾德干涉的全光纤双参量传感器

提出一种基于S形-错位结构的全光纤马赫-曾德干涉仪（MZI）双参量传感器。该传感结构是采用单模光纤在光纤熔接机中通过简单的放电和熔接等步骤制备而成。顺时针扭转时, 传感器的传输光谱向短波长方向偏移; 逆时针扭转, 向长波长方向偏移。对传感器的实验研究结果表明,该传感器在光纤横截面上顺时针和逆时针两个旋转方向上的扭曲传感灵敏度分别为−223 pm/(rad·cm⁻¹), 140 pm/(rad·cm⁻¹),且可实现扭转方向的判别,在一定应变范围内的应变灵敏度为0.145×10⁶ dB/ε(这里ε为应变),且温度交叉灵敏度极小,可忽略不计。因此,这种基于单模光纤的纤芯-包层MZI双参量传感器具有传感灵敏度高,体积小巧,工艺简单,成本低廉且可判别扭转方向的优点,有望成为众多双参量测量操作中良好的候选仪器之一。     

A smart optical liquid level sensor based on Hg cladding optical waveguide

A smart optical liquid level sensor based on the theory of connected vessels is introduced. The Hg cladding optical waveguide (HCOW) is taken as its probe, and the change of liquid level is presented by the change of the HCOW length. Both the theoretical analysis and experiments show that when the waveguide diameter and the light wavelength are certain, the optical power loss decreased linearly with the increase of the HCOW length. By detecting the power loss of HCOW, optimizing the structure of probe and selecting the appropriate apparatus for detection, the real time detection of liquid level with high precision can be got. The experimental results show that the measurement accuracy is 5.2 mm within 10 m liquid level, and its theoretical precision can be up to 0.02%.     

Measurement technique for characterizing odd aberration of lithographic projection optics based on dipole illumination

A dipole illumination based measurement technique for measuring odd aberration of lithographic projection optics is proposed. In the present technique, odd aberration is extracted from the image displacements at multiple illumination settings. Theoretical analysis of the impact of illumination profile on the measurement accuracy is presented. By use of dipole illumination, the image displacement variation range that determines the measurement accuracy is enlarged. Using lithographic simulator PROLITH, the measurement accuracies of odd aberration under conventional illumination and dipole illumination are compared. The simulation results show that the measurement accuracy of odd aberration increases significantly when dipole illumination is used.     

基于压缩感知的矢量阵聚焦定位方法

本文针对噪声源近场定位识别问题,利用声源分布在空间域具有稀疏性,在压缩感知理论框架下建立了新体系下的矢量阵聚焦波束形成方法,用于解决同频相干声源的定位识别问题.新方法可在小快拍下准确获得噪声源的空间位置,且不损失对噪声源贡献相对大小的评价能力.通过详细的理论推导、仿真分析和试验验证,证明了基于压缩感知的矢量阵聚焦定位新方法本质上实现了l1范数正则化求解下的波形恢复和空间谱估计,因此具有较高的定位精度,较强的相干声源分辨能力、准确的声源贡献相对大小评价能力以及较高的背景压制能力,可应用于水下复杂噪声源的定位识别.     

基于Kinect传感器多深度图像融合的物体三维重建

物体的三维重建技术一直是计算机视觉领域研究的热点问题,提出一种利用Kinect传感器获取的深度图像实现多幅深度图像融合完成物体三维重建的方法。在图像空间中对深度图像进行三角化,然后在尺度空间中融合所有三角化的深度图像构建分层有向距离场（hierarchical signed distance field）,对距离场中所有的体素应用整体Delaunay三角剖分算法产生一个涵盖所有体素的凸包,并利用Marching Tetrahedra算法构造等值面,完成物体表面重建。实验结果表明,该方法利用Kinect传感器采集的不同方向37幅分辨率为640480的深度图像完成目标物体的三维重建,仅需要48 s,并且得到非常精细的重建效果。     

一种基于CMOS图像传感器的大视场角度测量装置的误差校正方法

基于CMOS图像传感器的大视场角度测量装置的设计方案,重点研究了装配误差和图像畸变对角度测量精度的影响,得到了系统的综合误差模型。介绍了利用经纬仪校正自准直光路中装配误差和图像畸变误差的步骤,即通过抽取量程内若干控制点,再根据综合误差模型拟合得到整个量程的校正数据。仿真实验验证了此方法的适用性,并将此方法和常见的分段线性插值法以及多项式拟合法进行了性能对比。     

Saliency Snake: A unified framework with adaptive initial curve

Active contour model also known as Snake, is a popular approach for contour extraction and image segmentation. However, some existing active contour models are sensitive to the initial curve, which is usually required to be placed near the true object contour. To address this problem, this paper proposes a novel active contour model with adaptive initial curve, namely Saliency Snake. Taking visual saliency into consideration, prior shape information of the interested object is incorporated explicitly into the energy functional of Saliency Snake. Such improvement facilitates active contour evolution and leads to fast and automatic segmentation. Experiment results demonstrate that the proposed Saliency Snake can achieve superior segmentation performance both in terms of accuracy and efficiency.     

Improvement of measurement range of optical fiber displacement sensor based on neutral network

By studying the output characteristics of random type optical fiber displacement sensor and semicircular type optical fiber displacement sensor, a sensor of new structure was designed. Using the ratio of the two output signals as the output of the whole system, the measurement range was enlarged, the linearity was improved, and the errors of reflective and absorbent changing in target surface are automatically compensated. Meantime, an optical fiber sensor model of correcting static error and linearizing the output curve based on BP artificial neural network was set up. The intrinsic errors such as fluctuations in the light, circuit excursion, the intensity losses in the fiber lines and the additional losses in the receiving fiber caused by bends were eliminated. By discussing in theory and experiment, the error of nonlinear is 2.9%, the measurement range reaches to 3.0 mm and the relative accuracy is 2%. This kind of sensor offers such advantages as no electromagnetic interference, simple construction, high sensitivity, good accuracy and stability.     

A new method to calculate corneal ablation depth based on optical individual eye model

The corneal shape, axial lengths and the wavefront aberrations of the eye were all considered to calculate the ablation depth based on the individual eye model. The optimization method for the curves surface replaced the direct calculation from only the optical path difference method (OPD). We analyzed the eye's optical system on its exit pupil and offered the optimum corneal anterior surface. And the ablation depth was the difference between the pre- and post-optimization along the optical axis of the eye. In our experiment, the maximum ablation depth decreases by 8.5% and the mean ablation depth decreases by 8.2% compared with the OPD method.     

基于Sigmoid函数的离轴照明光源全参数解析模型

本文提出一种全面描述光刻机离轴照明光源物理分布特性的全参数解析模型,该模型采用Sigmoid函数作为构造各种主流离轴光源解析模型的核函数.提出通过加入光源全参数修正项来表征真实光源的各种物理畸变和偏差,全参数修正项可展开为傅里叶级数形式,相应级次的傅里叶系数具有特殊的物理意义,可分别代表偏心、倾斜、椭偏等形式的光源畸变,为光刻分辨率增强技术及其相关领域提供了仿真条件与理论依据,具有重要的应用价值. 关键词： 光学光刻 光源模型 Sigmoid函数 离轴照明