超分辨近场结构光磁混合存储介质的温度场模拟

为了进一步减小光磁混合存储记录位尺寸,建立了用于光磁混合存储记录介质的超分辨近场结构膜层模型、近场光场模型及温度场模型,采用有限元方法对超分辨近场结构光磁混合存储介质记录层的温度场进行了计算模拟.计算小采用日的光磁混合记录介质膜层结构为C(2 nm)/Sb(10 nm)/SiN(10 nm)/CO75Cr15Pt10(30 nm).当写入温度为550 K时,随着入射激光功率的增加,光磁混合存储介质记录层温度场可写入区域面积增加.当激光功率从3.9 mW增至6.9 mW时,温度场可写入区域横向及纵向尺寸增加约1倍,记录密度减小至原记录密度的1/4.     

面向超分辨光学成像的浸没微球透镜控制

微球透镜配合传统光学显微镜可以采集到衍射极限以下的超分辨光学图像,为了精确控制微球透镜在样品表面的位置,同时扩大超分辨成像范围,提出了一种控制微球透镜的方法,结合多轴微动平台实现微球透镜的精确定位与成像扫描操作。通过光学仿真分析了微球透镜超分辨成像效果,并对精密微动平台进行了运动学分析。为了提高超分辨成像效果,将微球透镜浸没于液体介质中,并对在液体中运动的微球透镜进行力学分析。通过实验,清晰分辨出130nm(~λ/4)的蓝光光碟条纹间隙,证明了微球透镜具有超分辨成像能力,结果表明,微球透镜可以在传统光学显微镜的基础上进一步提高约3.52倍的放大倍数。通过控制微球透镜以5×10~(-6) m/s的速度在液体中按"S"型轨迹移动,实现了对一个视场内样品的超分辨成像,此控制方法可以精确控制微球透镜的运动,通过扫描的方式可以扩大微球透镜的观测范围,提高观测速度。     

一种基于大视野的微操作系统的目标定位方法

针对微操作系统中位于视野之外的操作对象的任意性,提出了一种对显微镜视野之外操作对象的自动定位方法,实验证明,该方法能将操作对象自动移至显微镜视场内,可提高工作效率,提高自动化程度。     

超分辨近场结构光磁混合存储介质温度场模拟

为了进一步减小光磁混合存储记录位尺寸,建立了用于光磁混合存储记录介质的超分辨近场结构膜层模型、近场光场模型及温度场模型,采用有限元方法对超分辨近场结构光磁混合存储介质记录层的温度场进行了计算模拟。计算中采用的光磁混合记录介质膜层结构为C(2nm)/Sb(10nm)/SiN(10nm)/Co75Cr15Pt10(30nm). 当写入温度为550K时,随着入射激光功率的增加,光磁混合存储介质记录层温度场可写入区域面积增加。当激光功率从3.9mw增至6.9mw时,温度场可写入区域横向及纵向尺寸增加约1倍,记录密度减小至原记录密度的四分之一。     

光学掩模实现几何超分辨成像的仿真

将基于实际CCD模型的频谱编码方法引入光电成像系统,以克服CCD对空间分辨率的限制,实现几何超分辨成像。介绍了光学掩模实现几何超分辨成像的工作原理,基于实际的CCD模型在4f成像系统的频谱面上放置光学编码掩模来提高图像分辨率。对该成像系统模型进行了数学分析,从理论上证明了这种基于实际CCD模型的频谱编码方法的有效性。根据建立的理论完成了基于一维光学编码掩模方法的仿真实验。仿真结果表明:提出的方法能实现几何超分辨成像,解决了光电成像系统中因CCD欠采样造成的物频谱混叠和因像素尺寸非零而造成的低通效应问题。与传统的超分辨方法相比,该方法的系统结构简单、易实现。     

利用异形像元探测器的超分辨成像方法

随着光学成像全面进入光电数字成像时代,大多数成像系统的空间分辨率受限于探测器,所以提高探测器分辨率成为高分辨光电成像系统中的核心问题。而探测器的低分辨率主要是由于低采样频率和像元感光区的孔径效应而造成。最直接的解决方法就是减小像元尺寸,但会降低其他性能参数;针对最主要的限制因素——采样频率不足,目前多采用基于过采样原理的超分辨重建技术,通过提高探测器采样的频率来提高探测器的空间分辨率,但是其提升效果受到像元孔径效应的制约。为了进一步提高探测器受限的成像系统的空间分辨率,提出一种基于异形像元探测器的超分辨成像方法,将两列线阵异形像元探测器亚像元推扫实现像元细分,然后利用两列探测器所输出的灰度矩阵信息,重建出最终的高分辨图像。并分别通过理论评估和具体实验两方面验证该方法可以同时提高探测器的采样频率和截止频率,拓展带宽,从而实现高分辨率的目的。     

融合3D对极平面图像的光场角度超分辨重建

针对光场成像中因硬件限制而造成的光场图像角度分辨率低的问题,提出一种融合3D对极平面图像的光场角度超分辨重建方法。该方法首先将输入图像按不同的视差方向排列分别进行特征提取,以充分利用输入图像的视差信息,提高深度估计的准确性。利用深度图将输入图像映射到新视角位置,生成初始合成光场。为了使重建光场图像能够保持更好的细节信息及几何一致性,先通过水平3D对极平面图像融合重建分支和垂直3D对极平面图像融合重建分支,分别对初始合成光场进行水平融合重建和垂直融合重建,再将两个结果进行混合重建,生成最终的高角度分辨率光场图像。实验结果表明：相比于现有方法,本文方法在合成光场数据集和真实光场数据集上的重建效果均得到了提高,峰值信噪比的提升幅度最高达1.99%,有效地提高了重建光场的质量。     

有序金纳米棒阵列的超分辨成像

显微成像技术受限于光学成像系统的衍射极限,无法分辨亚波长尺度的结构。通过饱和散射抑制成像技术已经实现了单个纳米颗粒的超分辨成像,但是涉及到纳米颗粒集合,需要考虑纳米颗粒间的耦合作用。利用超越衍射极限的双光束方法,可以在有序金纳米棒阵列上实现远场超分辨光学成像。本文设计了纳米棒长径比为2的5×5金纳米棒阵列,通过矢量光场理论和热扩散理论计算了金纳米棒阵列在连续波激光下的热分布,并模拟了双光束激光即脉冲激发光和连续波抑制光下的散射成像。仿真结果显示,连续波激光能够有效抑制金纳米棒阵列对脉冲激光的散射,双光束方法实现了80 nm横向特征尺寸的超分辨成像。     

亚像元的CCD几何超分辨方法

为了在现有CCD像元尺寸的基础上提高CCD像元分辨力,对CCD几何超分辨问题进行了研究.从研究现状入手,给出了现有算法及其不足,建立了亚像元超分辨成像数学模型,提出了亚像元的CCD几何超分辨方法.该方法将两片线阵CCD集成在同一器件中,在线阵方向上错开半个像元,同时读出时间减半,最终交织重组图像数据,以合成高分辨率图像.利用MATLAB 7.0.1软件对双线性插值方法及亚像元成像方法进行了仿真,并定性定量地分析了两种方法的效果.结果显示:亚像元方法合成图像分辨率约为低分辨率图像的2倍,且两组仿真图像中的PSNR比双线性插值图像分别高出1.486 4 dB和2.207 0 dB.该方法可以显著地减轻欠采样引起的图像模糊,且实时性优于双线性插值方法.     

无源毫米波成像投影Landweber多重网格超分辨算法

在无源毫米波成像应用中,由于天线孔径大小的限制而导致获得的图像有可怜的分辨率,因此必须采取有效的后处理措施增强图像的分辨率。本文提出了一种针对无源毫米波成像应用的投影Landweber多重网格超分辨算法,该算法以投影Landweber算法作为主迭代过程,通过逐步频域内插避免了频谱混叠,从而实现频谱外推和超分辨。实验结果表明,该算法改善了收敛速度,增强了图像的分辨率,减少了计算量,有利于无源毫米波成像超分辨的实时实现。     

Simultaneous multicolour imaging using quantum dot structured illumination microscopy

Multicolour structured illumination microscopy (SIM) is a powerful tool used for the investigation of the dynamic interaction between subcellular structures. Nevertheless, most of the multicolour SIM schemes are currently limited by conventional fluorescent dyes and wavelength-dependent optical systems, and can only sequentially record images of different colour channels instead of obtaining multicolour datasets simultaneously. To address these issues, we present a novel multicolour SIM scheme referred to as quantum dot structured illumination microscopy (QD-SIM). QD-SIM enables simultaneously excitation and collection of multicolour fluorescent signals. We also propose a theoretical analysis of the image formation in two-dimensional multicolour SIM to help combine the optically sectioned and super-resolution attributes of SIM. Based on this theory, QD-SIM enables optically sectioned, super-resolution, multicolour simultaneous imaging at a single plane.     

Two‐dimensional structured illumination microscopy

In widefield fluorescence microscopy, images from all but very flat samples suffer from fluorescence emission from layers above or below the focal plane of the objective lens. Structured illumination microscopy provides an elegant approach to eliminate this unwanted image contribution. To this end a line grid is projected onto the sample and phase images are taken at different positions of the line grid. Using suitable algorithms ‘quasi‐confocal images’ can be derived from a given number of such phase‐images. Here, we present an alternative structured illumination microscopy approach, which employs two‐dimensional patterns instead of a one‐dimensional one. While in one‐dimensional structured illumination microscopy the patterns are shifted orthogonally to the pattern orientation, in our two‐dimensional approach it is shifted at a single, pattern‐dependent angle, yet it already achieves an isotropic power spectral density with this unidirectional shift, which otherwise would require a combination of pattern‐shift and ‐rotation. Moreover, our two‐dimensional approach also yields a better signal‐to‐noise ratio in the evaluated image.     

Spatial calibration of structured illumination fluorescence microscopy using capillary tissue phantoms

Quantitative assessment of microvascular structure is relevant to the investigations of ischemic injury, reparative angiogenesis and tumor revascularization. In light microscopy applications, thick tissue specimens are necessary to characterize microvascular networks; however, thick tissue leads to image distortions due to out-of-focus light. Structured illumination confocal microscopy is an optical sectioning technique that improves contrast and resolution by using a grid pattern to identify the plane-of-focus within the specimen. Because structured illumination can be applied to wide-field (nonscanning) microscopes, the microcirculation can be studied by sequential intravital and confocal microscopy. To assess the application of structured illumination confocal microscopy to microvessel imaging, we studied cell-sized microspheres and fused silica microcapillary tissue phantoms. As expected, structured illumination produced highly accurate images in the lateral (X-Y) plane, but demonstrated a loss of resolution in the Z-Y plane. Because the magnitude of Z-axis distortion was variable in complex tissues, the silica microcapillaries were used as spatial calibration standards. Morphometric parameters, such as shape factor, were used to empirically optimize Z-axis software compression. We conclude that the silica microcapillaries provide a useful tissue phantom for in vitro studies as well as spatial calibration standard for in vivo morphometry of the microcirculation.     

Surpassing the lateral resolution limit by a factor of two using structured illumination microscopy

Lateral resolution that exceeds the classical diffraction limit by a factor of two is achieved by using spatially structured illumination in a wide-field fluorescence microscope. The sample is illuminated with a series of excitation light patterns, which cause normally inaccessible high-resolution information to be encoded into the observed image. The recorded images are linearly processed to extract the new information and produce a reconstruction with twice the normal resolution. Unlike confocal microscopy, the resolution improvement is achieved with no need to discard any of the emission light. The method produces images of strikingly increased clarity compared to both conventional and confocal microscopes.     

噪声对超分辨率重构结果影响的分析

结合成像模型,从数学角度分析了噪声对重构结果的影响,结合POCS算法,仿真了常见成像模型中噪声对重构结果的影响。通过MATLAB软件仿真获取低分辨率图像序列集,并对低分辨率图像施加噪声获取带有噪声的低分辨率图像集,再借助算法获取高分辨率图像。根据实际情况的不同,分别仿真分析了不同程度的高斯噪声和乘性噪声以及椒盐噪声对最终重构结果的影响。研究结果表明:不论何种噪声,其对重构结果的影响趋势基本一致,即较小噪声对于重构结果影响较小,但随着噪声的增加,图像质量严重退化,重构结果中信噪比相对于原始图像下降更快,图像质量更差;另一方面在相同的信噪比情况下,高斯噪声对于重构结果的影响最大。     

Out‐of‐focus background subtraction for fast structured illumination super‐resolution microscopy of optically thick samples

We propose a structured illumination microscopy method to combine super resolution and optical sectioning in three‐dimensional (3D) samples that allows the use of two‐dimensional (2D) data processing. Indeed, obtaining super‐resolution images of thick samples is a difficult task if low spatial frequencies are present in the in‐focus section of the sample, as these frequencies have to be distinguished from the out‐of‐focus background. A rigorous treatment would require a 3D reconstruction of the whole sample using a 3D point spread function and a 3D stack of structured illumination data. The number of raw images required, 15 per optical section in this case, limits the rate at which high‐resolution images can be obtained. We show that by a succession of two different treatments of structured illumination data we can estimate the contrast of the illumination pattern and remove the out‐of‐focus content from the raw images. After this cleaning step, we can obtain super‐resolution images of optical sections in thick samples using a two‐beam harmonic illumination pattern and a limited number of raw images. This two‐step processing makes it possible to obtain super resolved optical sections in thick samples as fast as if the sample was two‐dimensional.     

基于内容的双字典学习及稀疏表示的图像重构

提出了一种基于内容的双字典学习和稀疏分解结合起来的算法.针对待复原图像内容间的差异性,将训练图像块采用聚类的方法得到多个分类式的字典,从中选择最合适的内容分类来进行图像的恢复,这样做使算法更具区分性,提升了图像的自适应能力.在此基础上,将高频信息分为主要高频和次要高频,并训练双重字典,结合稀疏表示的方法对图像进行重构,这比传统的基于字典学习的算法捕获了更多的图像高频信息,进一步提升了图像重构的质量.方法采用了K-SVD算法以提高稀疏字典编码的计算效率.与其他方法相比,该算法获得了更为精细的图像细节,在PSNR测试数据和主观视觉上都获得了理想的提升.     

融合层次特征和注意力机制的轻量化矿井图像超分辨率重建方法

针对矿井图像灰暗模糊、边缘不清晰等问题,提出了一种融合层次特征和注意力机制的轻量化矿井图像超分辨率重建方法。首先设计一种残差坐标注意力模块,在残差块中融入坐标注意力机制,使网络获得更丰富的高频细节信息;其次采用层次特征融合机制,对不同网络层次的特征信息进行特征融合,促进边缘细节信息的重建。最后,再对融合后的特征进行降维以减少模型计算量和参数量。为了使模型在真实矿井场景中具有更好的泛化能力,构建了一种煤矿井下图像数据集CMUID用于网络模型的训练和测试实验。实验结果表明,本文算法的重建图像质量在客观指标和主观感受上均优于其他对比算法。当缩放因子为4时,与OISR算法相比,在煤矿井下数据集上PSNR和SSIM的平均值分别提升了0.318 5 dB和0.012 6,在公共数据集上PSNR和SSIM的平均值分别提升了0.1 dB和0.003 5;网络模型参数量减少了70.7%。     

基于面结构光投影法的刀具几何参数测量研究

先进制造技术中高效切削刀具的几何形状与几何参数是否合理直接影响刀具的使用寿命以及产品的加工质量,针对这个问题,采用面结构光投影法对高效切削刀具的几何参数进行非接触式测量,此方法不仅能够准确重建出用于其几何参数测量的刀具三维模型,还能够直观反映刀具表面有无缺陷。主要对面结构光投影法基本思想、测量系统数学模型和点云旋转拼接进行了研究,并给出了刀具转台坐标系和CCD摄像机成像坐标系之间的变换关系,并对直柄麻花钻进行测量实验,实际结果测量结果的比较表明面结构光投影法可有效对刀具进行测量,且测量精度较高。