高光谱遥感技术在生物多样性保护中的应用研究进展

当今世界物种的减少和栖息地的丧失日益严重,生物多样性保护已经成为最热门的话题之一。遥感这种通过非接触式收集信息的科学,及相应的估算生物多样性、建立物种多样性的关系模型和进行生物多样性指数制图等功能,已在生物多样性保护领域中得到了广泛应用。从遥感传感器和遥感技术两个方面论述了高光谱遥感技术在生物多样性保护中的应用进展,重点列举了光谱遥感在生物多样性保护中的成功应用实例。对生物多样性保护的发展具有一定的参考价值。     

Nonlinear imaging microscopy techniques as diagnostic tools for art conservation studies

We present results of the implementation of three-photon excitation fluorescence (3PEF) and third harmonic generation imaging measurements for the precise and nondestructive detection of natural and synthetic varnish layers, which are used for the surface protection of painted artifacts. For this purpose, we employ as an excitation source a compact femtosecond laser operating at 1028 nm. Two-dimensional images of the multilayer structures from different samples are depicted. The third harmonic signals show the interface between the different materials, when its refractive index mismatch is high enough. The depths of different layers of varnishes, presenting similar refractive index, are distinguishable with an axial resolution of approximately 1 microm by employing 3PEF measurements.     

高速多光谱 TDI CCD 成像电路系统

为实现多光谱TDI CCD的高速高信噪比成像,利用可空间应用的多光谱TDI CCD传感器研制出了高性能成像电路系统。该系统以现场可编程门阵列（ FPGA）为核心逻辑单元,带有RS422外围通信控制接口,并采用CAMERALINK接口输出图像数据。系统具有动态推扫成像的能力,可同时输出全色和彩色两种模式的图像数据。利用灰度条纹的靶标对传感器的3个多光谱（ R、G、B）感光区标定白平衡,利用彩色条纹的靶标对系统进行成像测试,在驱动频率为15 MHz的情况下,系统单片CCD输出的图像数据率达到1.2 Gbps。试验结果表明,获取全色图像的信噪比达到了53.56 dB,各多光谱图像的信噪比较高的也在40 dB以上,满足空间对地高分辨多光谱遥感成像的技术指标要求,对高速空间多光谱遥感相机的研制具有借鉴意义。     

分孔径中波红外多光谱成像光学系统的设计

为了同时获得目标的红外图像信息和光谱信息,设计了一种分孔径中波红外分波段成像光学系统。该系统可将位于成像器前方不同波段的目标红外场景通过分孔径方式成像到红外制冷型探测器的4个区域上。该系统通过内部分孔径的办法,在不同通道内放置滤光片的方式,实现在一个探测器上对3.5 μm~4.1 μm、4.4 μm~5 μm、3.5 μm~5 μm、4.4 μm不同波段的目标同时成像。该系统F数为1.93,单通道的焦距为60 mm,MTF接近衍射极限,同时实现了在-40℃~+60℃的无热化需求,可以满足应用和指标需求。     

Terahertz-based nanometrology: multispectral imaging of nanoparticles and nanoclusters in suspensions

Silica nanoparticles suspended in an organic solvent (nanosuspension) have been imaged and characterized via terahertz nanoscanning reconstructive three-dimension (3D) imaging technique. The size of individual silica nanoparticles in the suspension was quantified. In addition, the presence of nanoclusters along with their distribution in the suspension was visualized in 3D. It has also been qualitatively demonstrated that the volume fraction of solvent is significantly higher than that of the silica nanoparticles; an observation consistent with the composition of the nanosuspension in the present investigation. The measured size range of individual nanoparticles was found to be 10–12 nm, while the manufacturer’s specification indicates a nanoparticle size distribution in the range of 10 to 15 nm. However, a typical nanocluster size was determined to be 17.5 nm, thus indicating the presence of nanoparticles less than 10 nm. The nanometrology instrument used in this investigation was based on a dendrimer dipole excitation-based continuous wave terahertz source generating >?200 mW stable terahertz power.     

A review of hyperspectral imaging for nanoscale materials research

As an emerging technology, hyperspectral imaging (HSI), which combines both advanced spectroscopy and imaging techniques, provides sufficient information for spectral and spatial analysis and is thus suitable for distribution and property investigation of nanoscale materials. Considering the applications of HSI have spread from remote sensing to quality control of macro products such as food and milk, this article reviews recent research of HSI in a new field of nanoscale materials. On the basis of fundamental parts of a HSI system, new techniques fitting specifically for nanoscale materials imaging such as dark field and Raman spectroscopy are introduced. Nanoscale materials, including metal nanoparticles, carbon nanotubes and graphene, biological components in cells and tissues, as well as multi-layer nanoscale materials, are the research hotspots utilizing HSI technology. Related research reports of the above materials are reviewed based on the physical distinction of these nanoscale materials. It is believed that HSI technology is a strongly potential technique for property investigation and manipulation of nanomaterial for various applications.     

Cultural heritage and archaeology materials studied by synchrotron spectroscopy and imaging

The use of synchrotron radiation techniques to study cultural heritage and archaeological materials has undergone a steep increase over the past 10–15 years. The range of materials studied is very broad and encompasses painting materials, stone, glass, ceramics, metals, cellulosic and wooden materials, and a cluster of organic-based materials, in phase with the diversity observed at archaeological sites, museums, historical buildings, etc. Main areas of investigation are: (1) the study of the alteration and corrosion processes, for which the unique non-destructive speciation capabilities of X-ray absorption have proved very beneficial, (2) the understanding of the technologies and identification of the raw materials used to produce archaeological artefacts and art objects and, to a lesser extent, (3) the investigation of current or novel stabilisation, conservation and restoration practices. In terms of the synchrotron methods used, the main focus so far has been on X-ray techniques, primarily X-ray fluorescence, absorption and diffraction, and Fourier-transform infrared spectroscopy. We review here the use of these techniques from recent works published in the field demonstrating the breadth of applications and future potential offered by third generation synchrotron techniques. New developments in imaging and advanced spectroscopy, included in the UV/visible and IR ranges, could even broaden the variety of materials studied, in particular by fostering more studies on organic and complex organic–inorganic mixtures, while new support activities at synchrotron facilities might facilitate transfer of knowledge between synchrotron specialists and users from archaeology and cultural heritage sciences.     

Modeling and compensating non-uniformity in push-broom NIR hyperspectral imaging system

In this paper, a novel pixel-based model for the response of push-broom near infrared (NIR) hyperspectral cameras based on focal-plane array (FPA) photo-detectors is proposed. The model focuses on practical issues affecting the system response, such as the spatial and spectral non-uniformity (NU) observed in NIR hyperspectral imaging systems, and its novelty relies on considering the operating temperature of the FPA as a signal perturbing the response of the entire system. These effects have been estimated by experimental procedures. The applicability and accuracy of the proposed model has been assessed by mitigating for the spatial and spectral non-uniform responses of a real NIR hyperspectral imaging sequence.     

高光谱遥感林业信息提取技术研究进展

高光谱遥感技术已成为林业遥感领域的前沿技术之一。回顾国内外高光谱遥感技术在林业信息提取中的研究进展,总结归纳了森林树种高光谱分类与识别、森林生态物理参数高光谱反演与提取、林木养分元素高光谱监测与诊断、森林郁闭度信息高光谱提取、森林灾害高光谱监测五个主要研究方面。在此基础上,文章指出了在林业遥感应用中高光谱技术尚待解决的关键问题,并阐述了可能解决问题的途径。最后对林业高光谱遥感技术的应用前景作了展望。     

Application of hyperspectral imaging for characterization of intramuscular fat distribution in beef

In this study, a hyperspectral imaging system in the spectral region of 400–1000 nm was used for visualization and determination of intramuscular fat concentration in beef samples. Hyperspectral images were acquired for beef samples, and spectral information was then extracted from each single sample from the fat and non-fat regions. The intramuscular fat content was chemically extracted and quantified for the same samples. Chemometrics including analysis of variance (ANOVA) and spectral similarity measures involving spectral angle measure (SAM), and Euclidian distance measure (EDM) were then used to analyze the data. An ANOVA analysis indicates that the two selected spectral variables (e.g., 650.4–736.4 nm) are effective to generate ratio image for visualization of the intramuscular fat distribution in beef. The spectral similarity analysis methods, which is based on the quantifying the spectral similarities by using predetermined endmember spectrum vector, provided comparable results for characterization and detection of intramuscular fat in beef. In term of overall classification accuracy, spectral similarity measure methods outperformed the ratio image of selected bands based on the result of ANOVA analysis. The results demonstrate that proposed technique has a potential for fast and nondestructive determination of intramuscular fat in beef.     

Near-Infrared spectroscopy and hyperspectral imaging for non-destructive quality assessment of cereal grains

Hyperspectral imaging (HSI) combines spectroscopy and imaging, providing information about the chemical properties of a material and their spatial distribution. It represents an advance of traditional Near-Infrared (NIR) spectroscopy. The present work reviews the most recent applications of NIR spectroscopy for cereal grain evaluation, then focuses on the use of HSI in this field. The progress of research from ground material to whole grains and single kernels is detailed. The potential of NIR-based methods to predict protein content, sprout damage and α-amylase activity in wheat and barley is shown, in addition to assessment of quality parameters in other cereals such as rice, maize and oats, and the estimation of fungal infection. This analytical technique also offers the possibility to rapidly classify grains based on properties such as variety, geographical origin, kernel hardness, etc. Further applications of HSI are expected in the near future, for its potential for rapid single-kernel analysis.     

Advances in imaging and electron physics

Collected Scientific Papers of Meghnad Saha. Edited by Santimay Cratterjee. (S. N. Guha Ray at Sree Saraswaty Press Ltd., 1970.) [Pp. xiii + 414.] £6.00. Scope: Survey; library; library (reference). Level: Specialist/postgraduate.

Collected Scientific Papers of Meghnad Saha. Edited by Santimay Cratterjee. (S. N. Guha Ray at Sree Saraswaty Press Ltd., 1970.) [Pp. xiii + 414.] £6.00. Scope: Survey; library; library (reference). Level: Specialist/postgraduate.

Cosmology. By Jean Charon. (Weidenfeld &; Nicolson World University Library, 1970.) [Pp.256.] Hardback £1.75; paperback £0.70. Scope: Survey; library. Level: General reader; undergraduate; school.

Activation Analysis. By M. Rakovi?. (Butterworth Group, 1970.) [Pp. 339.] £6.00. Scope: Textbook; library. Level: Specialist/postgraduate.

Tables for Group Theory. By P. W. Atkins, M. S. Child and C. S. G. Philips. (Oxford University Press, 1970.) [Pp. ii + 32.] 25p. Scope: Library (reference). Level: Specialist/postgraduate; undergraduate.

Physical Applications of Vectors and Tensors. By Horst Teichmann. (George C. Herrap &; Co., Ltd., 1970.) [Pp. x + 235.] £3.25 and £2.60. Scope: Treatise/Textbook. Level: Undergraduate.

Jacobian Elliptic Function Tables. By L. M. Milne-Thomson. (Macmillan &; Co., Ltd., 1970.) [Pp. xi + 123.] $1.65. Scope: Library (reference). Level: For specialists only.

Atomic Spectra. By H. G. Kuhn. (Longmans, 1970.) [Pp. i + 472.] £5.25. Scope: Treatise. Level: Spccialist/postgraduate.

Magnetic Resonance. Edited by C. K. Coogan, Norman S. Ham, S. N. Stuart, J. R. Pilbrow and G. V. H. Wilson. (Plenum Publishing Corporation, 1970.) [Pp. xiii + 386.] $16.00. Scope: Conference proceedings. Level: For specialists only.

An Introduction to Liquid Helium. By John Wilks. (Oxford: Clarendon Press, 1970). [Pp. i + 165.] £1.40. Scope: Survey. Level: Postgraduate.

Introduction to the General Theory of Particle Transfer. By V. Kourganoff. (Gordon and Breach Science Publishers Ltd., 1970.) [Pp. xiii + 216.] £7.00. Scope: Treatise/textbook. Level: Specialist/postgraduate.

Hot Electron Microwave Generators. By John E. Carroll. (Edward Arnold Publishers Ltd., 1970.) [Pp. xiii + 306.] £6.00. Scope: Treatise/textbook Level: Specialist/postgraduate.

Modern Diffraction and Imaging Techniques in Material Science. Edited by S. Amelinckx, R. Gevers, G. Remaut and J. Van Landuyt. (North-Holland, 1970.) [Pp. viii + 745.] £12.60. Scope: Textbook. Level: For specialists only; specialist/postgraduate.

An Introduction to Electronics. By Dennis F. Shaw. (Longmans, 1970.) [Pp. viii + 397.] £3.00. Scope: Treatise/textbook; library. Level: Undergraduate.

Introduction to Semiconductor Devices. By M. J. Morant. (George G. Harrap &; Co. Ltd., 1970.) [Pp. 143.] 90p. Scope: Textbook. Level: Undergraduate.

Thin Film Physics. By O. S. Heavens. (Methuen &; Co. Ltd., 1970.) [Pp. vii + 152.] £2.00. Scope: Survey; library. Level: General reader; specialist/postgraduate.

Optics, Painting and Photography. By M. H. Pirenne. (Cambridge University Press, 1970.) [Pp. xv + 199.] £4.00. Scope: Treatise; library. Level: General reader.

Nuclear Reactions. By D. F. Jackson. (Methuen &; Co., Ltd., 1970.) [Pp. x + 260.] £3.25. Scope: Textbook. Level: Post-graduate.

Particles and their Interactions. By J. G. Powles. (Addison-Wesley Publishing Co., Inc., 1970.) [Pp. xii + 260.] £2.35. Scope: Textbook. Level: Undergraduate/General reader.     

Toward a UV-visible-near-infrared hyperspectral imaging platform for fast multiplex reflection spectroscopy

A reflection hyperspectral imaging system covering a 350-1000nm spectral range is realized by a UV-visible-near-IR Fourier transform imaging spectrometer. The system has a simple design and good spectral and spatial resolving performance. Accurate and fast microspectroscopic measurement results on novel colloidal crystal beads demonstrate the system has practical potential for high-throughput molecular multiplex assays.     

Discrimination methods for biological contaminants in fresh-cut lettuce based on VNIR and NIR hyperspectral imaging

The rapid detection of biological contaminants such as worms in fresh-cut vegetables is necessary to improve the efficiency of visual inspections carried out by workers. Multispectral imaging algorithms were developed using visible-near-infrared (VNIR) and near-infrared (NIR) hyperspectral imaging (HSI) techniques to detect worms in fresh-cut lettuce. The optimal wavebands that can detect worms in fresh-cut lettuce were investigated for each type of HSI using one-way ANOVA. Worm-detection imaging algorithms for VNIR and NIR imaging exhibited prediction accuracies of 97.00% (RI_547/945) and 100.0% (RI_1064/1176, SI_1064-1176, RSI-I_{(1064-1173)/1064}, and RSI-II_{(1064-1176)/(1064+1176)})_, respectively. The two HSI techniques revealed that spectral images with a pixel size of 1 × 1 mm or 2 × 2 mm had the best classification accuracy for worms. The results demonstrate that hyperspectral reflectance imaging techniques have the potential to detect worms in fresh-cut lettuce. Future research relating to this work will focus on a real-time sorting system for lettuce that can simultaneously detect various defects such as browning, worms, and slugs.     

超声分子成像进展

超声分子成像在超声医学成像的基础上,利用靶向超声造影剂为分子探针,以可视化和定量获取活体组织细胞的分子信息为目标的影像术。它不用进行手术活检,不仅可以给出病灶的空间信息,而且能确定它的性质,进行针对性的治疗和对疗效进行评估。本文对现有的核医学分子成像,磁共振分子成像,光学分子成像和光声分子成像技术作了简单介绍,着重讨论了超声分子成像技术和应用的进展。     

分子超光谱成像系统及其生物医学应用

设计出一种基于AOTF(acousto-optic tunable filters)的分子超光谱成像系统(MHSI).整个系统由显微镜、分光计、CCD镜头、数据采集卡和计算机等几部分组成.系统的光谱范围为550～1 000 nm,可采集225个波段,光谱分辨率优于2nm,空间分辨率达到0.3μm.由于系统的光源对样本的...     

利用光谱和质谱成像技术实现指纹痕量检测

近年来,依赖于先进光源的化学成像技术迅速发展,极大提高了痕量检测的准确性,在公共安全、环境、食品、医药、考古等领域具有重要的实用价值.在痕量检测中,通过将成像技术与光谱测量技术、质谱技术等相结合,能够同时获取检验对象的物质组成和二维图像信息,不仅可以揭示材料表面的痕量物质成分及其分布,还可以在提高检验灵敏度的情况下,减少甚至避免传统检测手段所需要的特殊显现剂,因此与其他检验方法具有良好的兼容性.本文以指纹检验这一典型的痕量检测问题为例,阐述基于光谱和质谱成像技术的化学成像方法在痕量检测领域中的应用,从定向针对特定组分的化学成像和非定向的直接化学成像两个方面,综述了在指纹显现或显现增强中获得应用的主要成像手段,包括可见-近红外成像、红外成像、拉曼成像、质谱成像等.     

Active hyperspectral imaging with a supercontinuum laser source in the dark

An active hyperspectral imaging(HSI) system was built with a supercontinuum(SC) laser illuminator and a visible/near-infrared hyperspectral camera, which was used for object spectrum detection in the dark. It was demonstrated that the Gaussian-like distribution of the SC illuminator can still be used for accurate reflectance spectrum measurement once the illuminator was characterized in advance. The validity of active HSI results was demonstrated by comparison with passive results. Then, the active HSI system was used to acquire reflectance spectra of different objects in just one pushbroom measurement successfully. With algorithms of principal component analysis clustering and unsupervised K-means spectral classification, this active HSI system with high spectral and spatial resolutions was demonstrated to be efficient and applicable for specific spectrum detections.