High Optical Magnification Three-Dimensional Integral Imaging of Biological Micro-organism

A high optical magnification three-dimensional imaging system is proposed using an optic microscope whose ocular （eyepiece） is retained and the structure of the transmission mode is not destroyed. The elemental image array is captured through the micro lens array. Due to the front diffuse transmission element, each micro lens sees a slightly different spatial perspective of the scene, and a different independent image is formed in each micro lens channel. Each micro lens channel is imaged by a Fourier lens and captured by a CCD. The design translating the stage in x or y provides no parallax. Compared with the conventional integral imaging of micro-objects, the optical magnification of micro-objects in the proposed system can enhanced remarkably. The principle of the enhancement of the image depth is explained in detail and the experimental results are presented.

Optical Antenna System Design for 3D Imaging Lidar

A new aspheric surface pre-collimation lenses system for the optical antenna of three-dimensional （3D） imaging of lidar has been optimally designed and simulated by optical design software CODE-V.Four kinds of aspheric surfaces spherical lenses including the sections of spherical,elliptical,hyperbola,and parabola have been researched.The optical system,including the elliptical cylinder lenses collimation and the optical antenna,can be realized less than 5 rad collimation angle for dot source semiconductor laser beam.

Application of composite field imaging in strip surface quality inspection

In strip surface quality inspection systems based on the machine vision detection technology ,image quality is a key factor affecting the final detection performance. Composite imaging methods, such as bright and dark field imaging or reflection and transmission imaging, can reveal more information by emphasizing different image aspects. Defect detection rates and defect recognition accuracy can be improved by integrating and matching information from different image acquisition settings. Practical application shows that transmission and reflection composite imaging can improve the imaging quality of penetrative defects, while bright and dark field composite imaging can enhance imaging of defects such as color deviation and stains.

Fast in vivo bioluminescence tomography using a novel pure optical imaging technique

Bioluminescence tomography(BLT)is a novel opt ical molecular imaging technique that advanced the conventional planar bioluminescence imaging(BLI)into a quantifiable three-dimensional(3D)approach in preclinical living animal studies in oncology.In order to solve the inverse problem and reconstruct tumor lesions inside animal body accurately,the prior structural information is com-monly obtained from X ray computed tomography(CT).This strategy requires a complicated hybrid imaging system,extensive post imaging analysis and involvement of ionizing radiation.Moreover,the overall robustness highly depends on the fusion accuracy between the optical and structural information.Here,we present a pure optical bioluminescence tomographic(POBT)system and a novel BLT workfow based on multi-view projection acquisition and 3D surface reconstruction.This met hod can reconstruct the 3D surface of an imaging subject based on a sparse set of planar white-light and bioluminescent images,so that the prior structural information can be offered for 3D tumor lesion reconstruction without the involvement of CT.The performance of this novel technique was evaluated through the comparison with a conventional dual-modality tomo-graphic(DMT)system and a commercialized optical imaging system(IVIS Spectrum)using three breast cancer xenografts.The results revealed that the new technique offered comparable in vivo tomographic accuracy with the DMT system(P>0.05)in much shorter data analysis time.It also offered significantly better accuracy comparing with the IVIS system(P<0.04)without sacrificing too much time.

Ionization wave propagation and cathode sheath formation due to surface dielectric-barrier discharge sustained in pulsed mode

This work deals with the experimental study of a surface dielectric-barrier discharge,as a part of the ongoing interest in the control of plasma induced electro-fluid dynamic effects(e.g.plasma actuators).The discharge is generated using a plasma reactor consisting of a fused silica plate which is sandwiched between two printed circuit boards where the electrodes are developed.The reactor is driven by narrow high voltage square pulses of asymmetric rising(25 ns)and falling(2.5μs)parts,while the discharge evolution is considered in a temporarily and spatially resolved manner over these pulses.That is,conventional electrical and optical emission analyzes are combined with high resolution optical emission spectroscopy and ns-resolved imaging,unveiling main characteristics of the discharge with a special focus on its propagation along the dielectric-barrier surface.The voltage rising part leads to cathode-directed ionization waves,which propagate with a speed up to 105m s~(-1).The voltage falling part leads to cathode sheath formation on the driven electrode.Τhe polarization of the dielectric barrier appears critical for the discharge dynamics.

Dielectric metasurfaces for distance measurements and three-dimensional imaging

Ultrathin metasurfaces have shown the capability to influence all aspects of light propagation.This has made them promising options for replacing conventional bulky imaging optics while adding advantageous optical properties or functionalities.We demonstrate that such metasurfaces can also be applied for single-lens three-dimensional(3-D)imaging based on a specifically engineered point-spread function(PSF).Using Huygens’metasurfaces with high transmission,we design and realize a phase mask that implements a rotating PSF for 3-D imaging.We experimentally characterize the properties of the realized double-helix PSF,finding that it can uniquely encode object distances within a wide range.Furthermore,we experimentally demonstrate wide-field depth retrieval within a 3-D scene,showing the suitability of metasurfaces to realize optics for 3-D imaging,using just a single camera and lens system.

Line-field confocal optical coherence tomography for three-dimensional skin imaging

This paper reports on the latest advances in line-field confocal optical cohere nee tomography(LC-OCT),a recently invented imaging technology that now allows the generation of either horizontal(x×y)section images at an adjustable depth or vertical(x×z)section images at an adjustable lateral position,as well as thre dimensional images.For both two-dimensional imaging modes,images are acquired in real-time,with real-time control of the depth and lateral positions.Three-dimensional(x×y×z)images are acquired from a stack of horizontal section images.The device is in the form of a portable probe.The handle of the probe has a button and a scroll wheel allowing the user to control the imaging modes.Using a supercontinuum laser as a broadband light source and a high numerical microscope objective,an isotropic spatial resolution of^1|im is achieved.The field of view of the three-dimensional images is 1.2 mm×0.5 mm×0.5 mm(x×y×z).Images of skin tissues are presented to demonstrate the potential of the technology in dermatology.

Simultaneous dual-contrast three-dimensional imaging in live cells via optical diffraction tomography and fluorescence

We report a dual-contrast method of simultaneously measuring and visualizing the volumetric structural information in live biological samples in three-dimensional(3D) space. By introducing a direct way of deriving the 3D scattering potential of the object from the synthesized angular spectra, we obtain the quantitative subcellular morphology in refractive indices(RIs) side-by-side with its fluorescence signals. The additional contrast in RI complements the fluorescent signal, providing additional information of the targeted zones. The simultaneous dual-contrast 3D mechanism unveiled interesting information inaccessible with previous methods, as we demonstrated in the human immune cell(T cell) experiment. Further validation has been demonstrated using a Monte Carlo model.

Determine the position of nanoparticles in cells by using surfaceenhanced Raman three-dimensional imaging

The development of efficient three-dimensional cell imaging technology is a necessary means to study cell composition and structure,especially to track and monitor the phagocytosis process of nanoparticles by cells.Herein,we prepared a MoO_(2)hollow nanosphere with a strong surface plasmon resonance effect in the visible light region,which exhibited an excellent surface enhanced Raman scattering effect.When the 4-mercaptobenzoic acid(4-MBA)molecules are modified,it can be efficiently used as Raman probe molecules to perform clear three-dimensional cell imaging.No matter when the nanoparticles are located inside the cell,outside the cell or partly inside the cell,they all can be clearly presented by this enhanced Raman probe molecule.These results provide a rapid and accurate method for three-dimensional imaging of cells,especially for tracking the phagocytosis of nanoparticles.

Use of a tissue clearing technique combined with retrograde trans-synaptic viral tracing to evaluate changes in mouse retinorecipient brain regions following optic nerve crush

Successful establishment of reconnection between retinal ganglion cells and retinorecipient regions in the brain is critical to optic nerve regeneration.However,morphological assessments of retinorecipient regions are limited by the opacity of brain tissue.In this study,we used an innovative tissue cleaning technique combined with retrograde trans-synaptic viral tracing to observe changes in retinorecipient regions connected to retinal ganglion cells in mice after optic nerve injury.Specifically,we performed light-sheet imaging of whole brain tissue after a clearing process.We found that pseudorabies virus 724(PRV724)mostly infected retinal ganglion cells,and that we could use it to retrogradely trace the retinorecipient regions in whole tissue-cleared brains.Unexpectedly,PRV724-traced neurons were more widely distributed compared with data from previous studies.We found that optic nerve injury could selectively modify projections from retinal ganglion cells in the hypothalamic paraventricular nucleus,intergeniculate leaflet,ventral lateral geniculate nucleus,central amygdala,basolateral amygdala,Edinger-Westphal nucleus,and oculomotor nucleus,but not the superior vestibular nucleus,red nucleus,locus coeruleus,gigantocellular reticular nucleus,or facial nerve nucleus.Our findings demonstrate that the tissue clearing technique,combined with retrograde trans-synaptic viral tracing,can be used to objectively and comprehensively evaluate changes in mouse retinorecipient regions that receive projections from retinal ganglion cells after optic nerve injury.Thus,our approach may be useful for future estimations of optic nerve injury and regeneration.

Simulation Topographical Surfaces Geographical and Geological Using Differential Geometry

By applying differential geometry to analogue models developed such a model is calculated for the geometrical shape. Dip measurements are critical data for geologists, and in particular for structural studies. They enable quantifying geologic features observed across the surface in order to model the sub-surface. Dip measurements are provided by direct or indirect sources: geological maps, fieldwork data, Digital Elevation Model (DEM). This quantification then allows for comparison of such models to measured field data and supplants the use interferometry Radar describes and compares 3-D deformations. This example supplements and is based on the material found in L.S.S.I.T. Theory as well as some of the experimental results with the new method are delineated.

基于机器视觉技术的高精度光学仪器表面动态变形测量研究

伴随着光学仪器精度的逐渐提高,其表面动态变形事件发生频率也呈现急剧增加的趋势,是影响与制约光学仪器发展与应用的主要因素之一。为了满足光学仪器的应用需求,提出基于机器视觉技术的高精度光学仪器表面动态变形测量方法。采用机器视觉设备获取高精度光学仪器表面图像,对表面图像进行灰度化处理、去噪处理与增强处理,以此为基础,应用SURF特征检测算法提取表面图像的特征点,通过FLANN算法匹配相邻图像的特征点,利用Delaunay三角化在表面图像区域形成三角网格,进一步计算表面图像特征点的位移与应变,从而实现高精度光学仪器表面动态变形的测量。实验数据显示:在横坐标为1μm时,应用提出方法获得的表面动态变形位移纵坐标为1.8μm,与实际位移基本保持一致,在实验组别为6时,应用提出方法获得的光学仪器表面动态变形应变数值为3μm,与实际应变数值保持一致,充分证实了提出方法具备较好的应用性能。

Precise 3D shape measurement of three-dimensional digital image correlation for complex surfaces

Three dimensional-digital image correlation （3D-DIC） is a widely used optical metrology in the experimental mechanics community because of its reliability, practicality, and flexibility. Although the precision of digital image correlation （DIC） has been thoroughly studied theoretically and numerically, verification experiments have seldom been performed, especially fbr complex surfaces with a small field of view （FOV）. In this work, the shape of a 1-yuan coin was measured using 3D-DIC; the shape was complex due to the presence of many fine details, and the FOV was relatively small because the coin diameter was only 25 mm. During the experiment, a novel strategy for speckle production was developed： white paint was simply sprayed onto the surface. Black paint was not used; instead, taking advantage of the reflective nature of the coin surface, polarized light and a Polaroid filter were introduced, and the polarization direction was carefully adjusted, ensuring that the spray pattern was extremely thin and that high-quality speckle images with significant contrast were captured. The three-dimensional coin shape was also successfully determined for comparison using a stylus profiler. The results demonstrate that 3D-DIC provides high precision in shape measurement even for complex surfaces with small FOV. The precision of 3D-DIC can reach 1/7000 of the field of view, corresponding to about 6 ~tm in this experiment.

一次性硬膜外腔内窥镜光学系统设计

为了获得硬膜外腔的大视场清晰影像,利用Q-type非球面设计了工作波段为可见光,视场角为90°,F数为4,接收器为0.14 cm(1/18 inch)CMOS传感器的一次性硬膜外腔内窥镜光学系统。系统由3片塑料透镜和1片盖玻片组成,其中第3片透镜采用Q-type非球面,结构简单、紧凑、成本低。像质评价结果表明:在奈奎斯特频率200 lp/mm处各视场的调制传递函数均大于0.27,接近衍射极限;各视场均方根半径都小于像元尺寸2.5μm,均在艾里斑范围内;最大剩余畸变小于20%,满足高像质要求。最后,对系统的鬼像进行了分析与规避,结果表明,光瞳鬼像形成的光斑能量弥散,对像面照度均匀性影响较小;焦点鬼像形成的光斑尺寸远大于主像点列图,对成像质量影响较小,满足成像要求。

折/衍混合光学系统在纳型星敏感器中的应用

微纳卫星是一种新兴的微小卫星,与之适配的纳型星敏感器的光学系统应在小型化的同时实现大相对孔径、高成像质量。针对这一需求,由星敏感器的系统设计精度和探测星等分配了光学系统设计参数及指标,设计了一种全视场17°、焦距25 mm、相对孔径1∶1.086、光学系统总长36.4 mm的七片式折衍混合结构的星敏感器光学系统。根据衍射元件的负色散特性,用折衍混合透镜代替常规材料正负透镜组合的方式减少了镜片数量,缩短了光学系统长度,并提高了光学系统的成像质量,使点扩散函数趋于正态分布,有利于质心提取精度的提高。所设计的光学系统在3×3像元内的能量集中度超过90%;最大畸变仅0.013%;全视场垂轴色差小于0.6μm。通过标量衍射理论计算衍射元件在520~780 nm内衍射效率可以达80%以上,通过杂散光分析软件ASAP对系统进行了视场内鬼像分析,系统在多级衍射时探测目标成像光斑路径下的光通量与最亮鬼像光斑路径下的光通量之比大于3.17×10^(4),验证了在极限星等为6.5时满足信噪比大于8.1的结论。最后对所设计的系统进行了公差分析,结果表明加工后该光学系统可满足微纳卫星对星敏感器的使用要求。

光学成像卫星实景三维技术应用及启示

文章归纳总结了具有实景三维应用能力的光学成像卫星的发展,调研了目前国外卫星实景三维技术应用产品,梳理了近年国外卫星实景三维产品在高精度三维基础数据开发、目标指示等方面的应用,研究了实景三维产品在遥感领域的市场潜力,提出光学成像卫星实景三维技术应用已成为国家的重要数据资源和生产要素,在民商用领域,卫星实景三维技术应用是引领遥感产业跨越式发展的途径之一。

基于自由曲面光学元件的大视场光学成像系统

面向机载探测系统大视场光学成像的需求,开展了大视场光学成像系统光学设计、自由曲面光学元件超精密加工、形位误差同步检测以及系统集成与成像实验研究。首先,采用视场扩展法进行大视场自由曲面离轴反射光学系统的设计;其次,进行铝合金自由曲面反射镜纳米精度加工和高频抑制工艺探索,并实现了基于计算全息元件的自由曲面形位高精度检测;最后,进行了光学系统的装调集成与成像实验。结果表明,系统的视场角为30°×5°,全视场光学传递函数值大于0.7,接近衍射极限,最大像元均方根半径为2.075μm,自由曲面光学元件的面形精度均方根(Root Mean Square,RMS)值优于20 nm,位置精度优于1μm,装配集成后能够满足大视场高分辨的场景使用要求,同时具备稳定可靠和快响制造等特点。

大口径非球面镜面形加工环带提取

数控小工具是现代大口径非球面镜面研磨抛光加工中常用的一种计算机控制表面成形技术。在数控小工具加工实践中,当非球面面形精修到一定精度时,面形残差常常表现为环带形式,与相邻部分面形相差较大。为提高加工效率,可以针对这些环带使用小口径研抛工具进行单独修正,因此需要提取环带的位置和宽度。文章提出一种适用于大口径非球面镜的加工方法,通过将面形残差的高度信息映射到色彩空间成为图像,然后使用K-Means聚类分割图像,选择目标区间,得到待加工环带,此时可以计算出环带的宽度信息用于确定研抛工具的大小;另一方面,对环带提取骨架得到位置信息,从而生成数控机床可用的加工路径。该方法应用于1.6m望远镜非球面主镜面形的处理,从中提取了待加工环带信息用于指导面形加工,经多次加工与辅助平滑修抛迭代,主镜面形RMS值优于1/40波长。

基于图像预处理的光学元件表面粗糙度测量系统

在测量光学元件表面粗糙度时,测量结果往往比较片面,为此设计基于图像预处理技术的光学元件表面粗糙度测量系统。获取原始元件表面粗糙度干涉图像,通过对表面形貌图像实施图像去噪处理与倾斜校正处理获取滤波结果,通过自适应中值滤波算法实施图像的去噪处理。在粗糙度参数评定模块中,根据取样长度对评定长度下定义,实施光学元件表面粗糙度的全面评定。利用设计系统测量三种光学元件的表面粗糙度。实验结果表明:通过设计系统能够获取高成像质量的表面粗糙度干涉图像,实现多种元件表面粗糙度的全面测量,具有一定应用价值。