用于大气临边探测的高光谱成像仪研制

用于大气临边探测的高光谱成像仪是一种探测大气痕量气体的新型空间光学遥感仪器。分析了利用高光谱成像仪进行大气临边探测的原理,设计并研制了一台紫外/可见高光谱成像仪原理样机,该样机光学系统由前置望远系统和改进的Czerny-Turner光谱成像系统组成,工作谱段为280～390 nm和560～780 nm,通过转轮切换紫外、可见滤光片分别探测这2个波段。高光谱成像仪原理样机质量为15 kg,体积500 mm×350 mm×200 mm。对该样机的性能进行了检测并测量了低压汞灯的光谱。性能检测结果表明,空间分辨力为0.44 mrad,光谱分辨力为1.3 nm,均满足设计指标要求。该样机结构紧凑、质量小,在空间大气痕量气体探测领域有广泛的应用前景。     

用于火星探测的声光可调谐滤波器成像光谱仪

面向火星探测,设计并研制了一种基于声光可调谐滤波器(AOTF)原理的成像光谱仪地面原理样机.该样机由前置光机系统和后置电子学系统组成,光学系统采用消色差远心光路结构,工作波段为550～1 000 nm,光谱分辨率为0.9～4.0 nm.在电子学系统中引入可编程片上系统技术,并设计了新型SpaceWire高速总线接口用于数据传输.样机在实验室定标的基础上,搭载于模拟火星探测器上进行了成像试验.试验结果表明:样机成像质量良好;与ASD光谱仪的一致性对比检验表明,光谱测量准确可靠,两者数据匹配精度超过96％.SpaceWire接口实现了100 Mb/s数据率的稳定传输,满足设计指标25 Mh/s的要求.样机的研制为A)TF成像光谱技术在火星遥感探测领域的应用奠定了技术基础.     

Extending immunofluorescence detection limits in whole paraffin-embedded formalin fixed tissues using hyperspectral confocal fluorescence imaging

A major problem in microscopic imaging of ex vivo tissue sections stained with fluorescent agents (e.g. antibodies, peptides) is the confounding presence of background tissue autofluorescence. Autofluorescence limits (1) the accuracy of differentiating background signals from single and multiple fluorescence labels and (2) reliable quantification of fluorescent signals. Advanced techniques such as hyperspectral imaging and spectral unmixing can be applied to essentially remove this autofluorescent signal contribution, and this work attempts to quantify the effectiveness of autofluorescence spectral unmixing in a tumour xenograft model. Whole-specimen single-channel fluorescence images were acquired using excitation wavelengths of 488 nm (producing high autofluorescence) and 568 nm (producing negligible autofluorescence). These single-channel data sets are quantified against hyperspectral images acquired at 488 nm using a prototype whole-slide hyperspectral fluorescence scanner developed in our facility. The development and further refinement of this instrument will improve the quantification of weak fluorescent signals in fluorescence microscopy studies of ex vivo tissues in both preclinical and clinical applications.     

基于特征吸收波长板的色散型高光谱传感器光谱定标技术

高光谱传感器的光谱定标是实现高光谱遥感定量化的关键。为了克服传统的基于单色仪扫描的光谱定标方法存在的设备昂贵、耗时等缺点,实现色散型高光谱传感器在野外或飞行中的实时、高精度定标,提出了一种基于特征吸收波长板的色散型高光谱传感器系统级光谱定标方法。分别对特征吸收波长板和漫反射参照体反射信号进行了比对测量,通过优化计算得到了传感器通道的中心波长和带宽。该方法消除了待定标传感器的光谱响应和光源的光谱能量分布带来的影响,能快速准确地实现色散型高光谱传感器的波长定位。运用该技术实现了对野外光谱辐射计FieldSpec(UV/VNIR的光谱定标,并对影响光谱定标精确度的因素进行了分析计算,结果表明,该方法实现的波长准确度0.5 nm,可满足色散型高光谱传感器实时、高精度光谱定标的需要。     

A white light confocal microscope for spectrally resolved multidimensional imaging

Spectrofluorometric imaging microscopy is demonstrated in a confocal microscope using a supercontinuum laser as an excitation source and a custom‐built prism spectrometer for detection. This microscope system provides confocal imaging with spectrally resolved fluorescence excitation and detection from 450 to 700 nm. The supercontinuum laser provides a broad spectrum light source and is coupled with an acousto‐optic tunable filter to provide continuously tunable fluorescence excitation with a 1‐nm bandwidth. Eight different excitation wavelengths can be simultaneously selected. The prism spectrometer provides spectrally resolved detection with sensitivity comparable to a standard confocal system. This new microscope system enables optimal access to a multitude of fluorophores and provides fluorescence excitation and emission spectra for each location in a 3D confocal image. The speed of the spectral scans is suitable for spectrofluorometric imaging of live cells. Effects of chromatic aberration are modest and do not significantly limit the spatial resolution of the confocal measurements.     

A new MNF–BM4D denoising algorithm based on guided filtering for hyperspectral images

This paper proposed a new MNF–BM4D denoising algorithm based on guided filtering to improve the denoising performance of the state-of-the-art Block-Matching and 4D filtering(BM4D) algorithm for hyperspectral images in the spatial and spectral domain. BM4D is firstly used to denoise hyperspectral images. Then Minimum Noise Fraction(MNF) algorithm is introduced to distinguish between the main component and the noisy component. Finally, the guided image filtering technology is utilized to further improve the denoising performance. A number of experiments on both simulated and real data are conducted to validate the effective denoising performance of the proposed method. Therefore, the proposed algorithm can be considered as a promising technique for hyperspectral imagery denoising.     

超光谱成像仪的精细光谱定标

为了精细标定棱镜色散超光谱成像仪1024×80光谱像元的中心波长和响应带宽,建立了一套光谱定标装置,提出了实现1nm光谱定标精度的定标方法。首先,介绍了产生谱线弯曲与谱线倾斜的原因,确定了精细光谱定标的方法和数据处理算法;然后,利用光谱定标装置测定了全部光谱响应像元的离散单色光响应值,利用高斯方程拟合了相对光谱响应曲线;最后,建立了中心波长矩阵表和带宽矩阵表,采用多项式拟合算法确定了空间视场像元的色散方程和光谱通道谱线弯曲方程,实验测定了温度变化谱线漂移结果。另外,还对光谱定标精度对辐射定标精度的影响进行了分析。光谱定标结果表明:超光谱成像仪的光谱定标精度达到了±1nm,各谱段带宽平均为8.75nm;色散方程及谱线弯曲与设计结果相符,谱线弯曲值为14～19nm,平均值为17nm;1nm的定标精度对辐射定标精度的影响分别小于1%(3000K黑体)和0.25%(6000K黑体),满足超光谱成像仪1nm光谱定标精度的要求。     

显微高光谱成像系统的设计

设计出一种基于棱镜 光栅 棱镜组合分光方式的显微高光谱成像实验系统.系统根据推帚式成像光谱仪的原理进行设计,采用棱镜 光栅 棱镜组合元件在后光学系统进行光谱分光,利用高精度载物台自动装置驱动样品进行推扫成像,选用PCI总线作为数据采集的微机接口.整个系统由显微镜、分光计、面阵CCD相机、载物台自动装置以及数据采集与控制模块等几部分组成.系统的光谱范围从400nm到800nm,120个波段,光谱分辨率优于5nm,空间分辨率大约1μm.该系统具有直视性、光谱分辨率高、结构紧凑、成本低等优点;不仅能够提供微小物体在可见光范围的单波段显微图像,而且能够获得图像中任一像素的光谱曲线,实现了光谱技术和显微成像技术的结合,成功的将成像光谱技术应用到显微领域,可广泛应用于临床医学、生物学、材料学、微电子学等学科领域.     

用于大气遥感探测的临边成像光谱仪

分析了大气临边成像光谱探测的原理,依据应用要求设计研制了光栅色散型紫外/可见临边成像光谱仪原理样机。该样机采用宽波段折射式消色差前置望远光学系统与改进的Czerny-Turner光谱成像系统匹配的结构形式,工作波段为540～800nm(一级光谱)和270～400nm(二级光谱),通过切换紫外、可见带通滤光片来实现两个波段分别探测,质量为8kg,体积为450mm×250mm×200mm。用该样机进行了实验室光谱实验,并对光谱分辨率进行了分析,测量了该样机的实际光谱分辨率。测量结果表明,该样机的实际光谱分辨率为1.3nm,接近其理论光谱分辨率1.12nm,满足设计指标1.4nm的要求,并具有体积小、质量轻等特点,适合空间遥感应用。     

Development of a spatially resolving x-ray crystal spectrometer for measurement of ion-temperature (T(i)) and rotation-velocity (v) profiles in ITER

Imaging x-ray crystal spectrometer (XCS) arrays are being developed as a US-ITER activity for Doppler measurement of T(i) and v profiles of impurities (W, Kr, and Fe) with ～7?cm (a/30) and 10-100 ms resolution in ITER. The imaging XCS, modeled after a prototype instrument on Alcator C-Mod, uses a spherically bent crystal and 2D x-ray detectors to achieve high spectral resolving power (E/dE>6000) horizontally and spatial imaging vertically. Two arrays will measure T(i) and both poloidal and toroidal rotation velocity profiles. The measurement of many spatial chords permits tomographic inversion for the inference of local parameters. The instrument design, predictions of performance, and results from C-Mod are presented.     

Fabrication and evaluation of a near-infrared hyperspectral imaging system

This paper describes modifications to a hyperspectral imaging microscope that extend its capabilities into the near-infrared (950–1300 nm). The major changes include installing a grating, charge-coupled device camera, and lenses and filters appropriate for infrared wavelengths. Calibration of the system and validation with lead sulfide quantum dots of known emission wavelength is reported. Cells from the breast carcinoma cell line SkBr3 were scanned with lead sulfide quantum dots that emit at 1100 nm as the background and an image which contains the integrated spectral data is presented. We also demonstrate that this instrument is capable of detecting the photoluminescence spectra of single-walled carbon nanotubes dispersed in aqueous solution.     

An optical spectrometer for a confocal scanning laser microscope

An optical spectrometer for the visible range has been developed for the confocal scanning laser microscope (CSLM) Phoibos 1000. The spectrometer records information from a single point or a user-defined region within the microscope specimen. A prism disperses the spectral components of the recorded light over a linear CCD photodiode array with 256 elements. A regulated cooling unit cools the diode array, thereby reducing the detector dark current to a level, which allows integration times of up to 60 s. The spectral resolving power, λ/Δλ, ranges from 400 at λ = 375 nm to 100 at λ = 700 nm. Since the entrance aperture of the spectrometer has the same diameter as the detector aperture of the CSLM, the three-dimensional spatial resolution for spectrometer readings is equivalent to that of conventional confocal scanning, that is, down to 0.2 μm lateral and 0.8 μm axial resolution with an N.A.=1.3 objective.     

轻小型高分辨率星载高光谱成像光谱仪

在小型化成像光谱仪的研制和应用中,如何同时实现轻量化、高地面分辨率和高信噪比是目前亟待突破的技术难题。本文通过将线性渐变滤光片分光技术和数字域时间延迟积分技术相结合,并对镜头进行紧凑化处理,设计了一款工作波段为403~988 nm、平均光谱分辨率为8.9 nm、系统总质量为7 kg的轻小型星载高光谱成像光谱仪。仿真和实验结果表明,该高光谱成像仪能在500 km轨道上得到刈幅宽度为50.5 km、地面分辨率为10 m的高光谱图像,且图像信噪比良好。该成像光谱仪可为微纳卫星获得高分辨率的高光谱图像提供技术支持,推动了我国高光谱遥感探测技术的发展。     

近红外高光谱成像技术快速鉴别国产咖啡豆品种

结合近红外高光谱成像技术和不同的判别分析模型对4种国产咖啡豆品种进行了快速无损判别。通过高光谱成像仪提取874~1 734nm波段内的光谱数据,去除首尾噪声波段后,分别基于925~1 680nm波段的全谱波段和通过连续投影算法(SPA)选择的特征波长,建立了偏最小二乘判别分析(PLS-DA)、随机森林(RF)、K最邻近算法(KNN)、支持向量机(SVM)模型和极限学习机(ELM)5种判别分析模型。基于上述判别模型对咖啡豆品种进行鉴别;然后通过准确率、命中率和否定率3个参数对鉴别结果进行了评价。实验显示,基于全谱和特征波段建立的模型均取得了较好的判别效果,其中ELM模型效果均为最优,每个品种建模集和预测集的准确率、命中率和否定率均在93.5%以上。研究结果表明,基于近红外高光谱成像技术结合模型判别分析方法可以实现对国产咖啡豆品种的识别,特征波长的选择减少了变量数,但判别效果与全谱相当。     

迷彩伪装的高光谱特性分析

现代战争中,高光谱成像技术开始应用于伪装目标识别。为了加强对高光谱图像的信息挖掘,确定可以用来进行伪装识别的目标高光谱特征,对高光谱成像条件下的迷彩伪装特性及影响伪装效果的因素进行了综合分析。在光谱维,从高光谱图像中直接提取光谱曲线,确定了图像对比度高、迷彩伪装特征明显的光谱波段为650⁷40nm、780740nm、780⁸00nm。利用光谱角进行相似度计算,分析了阴影对光谱曲线的影响。在空间维,通过主成分分析和灰度共生矩阵的计算,得出了迷彩伪装纹理具有均匀性好、相关性强、复杂程度低等特点。研究结果为迷彩伪装的设计及识别提供了理论参考。     

红外高光谱干涉仪辐射定标误差敏感性因子的仿真分析

鉴于对高精度高时空分辨率大气探测资料日益增长的科研和业务需求,我国正大力发展星载红外高光谱探测系统。星载红外高光谱干涉仪光机结构复杂,仪器状态会显著影响其定标精度。本文通过理论分析和仿真实验,分别讨论了内黑体发射率、低温黑体发射率、内黑体与环境温度差、非线性系数以及直流电压演算等误差敏感性因子影响辐射定标精度的特征。分析表明定标辐射偏差的绝对值与内黑体/低温黑体发射率呈线性关系,且与内黑体与环境温度差、非线性系数、直流电压呈正相关;提高内黑体发射率和低温黑体发射率到0.985以上、控制内黑体与环境温度差在0.6 K左右、控制干涉仪的非线性效应系数低于0.04,这些方案均是实现0.1 K辐射定标精度的必要条件;辐射定标参数对定标辐射的影响特征结合地面真空实验的定标参数估计,可以迭代得到已测得和未知的定标参数的最优估计,从而提高定标精度。本文的研究结果对于红外高光谱干涉仪的参数设计以及辐射定标误差来源的识别和订正有着十分重要的意义。     

星载多谱段双视场紫外大气探测仪

针对天底和临边综合紫外大气探测的需求,分析了天底和临边双视场观测原理和技术指标,设计和研制了多谱段双视场紫外大气探测仪原理样机。该样机光学系统由前透镜组、环形透镜、中继透镜组和窄带滤光片组成,3个工作谱段的中心波长分别为265nm、295nm和360nm,带宽均小于20nm,天底视场为10°,临边视场为360°(141.8°~146.6°),焦距为5mm,F数为3.3,通过切换窄带滤光片完成3个谱段的探测。多谱段双视场紫外大气探测仪整机质量约为3kg,体积为Φ90mm×300mm。对样机的静态传递函数和像面照度均匀性进行了测试。测试结果表明,在特征频率38.5lp/mm处,天底视场的静态传递函数为0.24,临边视场的静态传递函数为0.22,像面照度均匀性为94%,均优于设计指标要求。该原理样机体积小、重量轻,满足空间光学遥感仪器小型化和轻量化的要求。     

激光扫描共聚焦光谱系统设计

为提高激光扫描共聚焦显微镜光谱模块的分光性能,设计了双Amici棱镜光谱结构.根据棱镜色散特性,计算得到Amici棱镜和双Amici棱镜的线性与非线性数学模型,给出直视型棱镜结构参数.比较相同色散条件下Amici和双Amici棱镜结构,得到双Amici棱镜组能提供更好的色散线性度.在光谱波段400～700 nm,中心波...     

谱线弯曲对成像光谱仪辐射信号采集的影响

为了研究谱线弯曲对棱镜色散成像光谱仪光谱辐射信号采集的影响。首先,给出探测器像元采集到的辐射能量的表达式。然后,结合复合棱镜的色散特性,在可见近红外光谱范围（400～1000nm）内,计算当光谱偏离量为0.01d、0.1d和0.5d（d为探测器像元尺寸）时系统采集到的辐射能量与没有谱线弯曲情况下系统采集到的辐射能量的归一化差值,衡量谱线弯曲下系统辐射测量的变化。结果表明：谱线弯曲引起的探测器上的光谱偏离导致系统辐射信号采集发生变化,与没有谱线弯曲的情况相比,采集到的景物辐射信号在大气吸收带的边缘出现明显的偏差,且信号的差值随光谱偏离量的增大而增大,当光谱分辨率提高时,一些较弱的吸收峰附近也会出现明显的信号偏差。对于光谱分辨率平均为10nm的成像光谱仪,谱线弯曲量应控制在0.3nm以内。     

宽谱段空间外差干涉光谱仪

研究了基于中阶梯光栅多级衍射特性实现谱段展宽的宽谱段空间外差干涉光谱仪的基础理论和系统设计方法。阐述了宽谱段空间外差干涉光谱仪的特点,分析了仪器性能指标(光谱分辨率、光谱范围、视场、信噪比、衍射级次等)与初始光学和电子学参数(光栅、视场棱镜、成像系统、探测器等)之间的理论关系。然后,设计并搭建了宽谱段空间外差干涉光谱仪实验平台,该系统的理论光谱分辨率为0.173cm-1@16 950cm-1,光谱区为500~700nm。最后,给出了激光(543.5nm、632.8nm)、Na灯(589nm、589.6nm)、Hg灯(576.96nm、579.07nm)光源的宽谱段实验结果,其复原光谱的平均波数采样间隔为0.17cm-1;光谱复原过程中采用三角切趾函数,平均光谱分辨率为0.39cm-1。实验结果与理论设计符合良好,且复原谱各级次之间的对应关系与光栅方程确定的理论关系完全符合。