高分辨率傅里叶变换光谱技术在短波段光学中的应用及进展

讨论了傅里叶变换光谱技术向短波段光学扩展的必要性和主要技术难点,分别介绍了几种应用于紫外、真空紫外及软Ｘ射线波段的傅里叶变换光谱仪结构性能与原理,并进一步阐述了高分辨率傅里叶变换光谱仪在短波段光学中的应用     

基于双直角分束器的反射式静态傅里叶光谱仪光学系统EI北大核心CSCD

基于双直角分束器设计了一种反射式静态傅里叶变换光谱仪光学系统,并搭建了样机。该光谱仪光学系统的分光装置采用双直角分束器,其他光路全部采用反射式结构,有效折叠光路,与透射式静态傅里叶光谱仪相比,系统体积减小一半以上。用汞灯作为静态傅里叶光谱仪光源时,得到了404.7,435.8,546.1,577.0nm的峰值谱线,实验结果很好地复原了汞灯实际光谱;用波长为650nm的激光进行实验,光谱分辨率约为5.93nm,与理论计算结果基本相符。该光学系统具有结构紧凑、体积小、重量轻、抗震性强等诸多优点,可为小型化、便携式静态傅里叶光谱仪器的研制提供技术支持。     

空间太阳极紫外三波段成像光谱仪系统设计

太阳上层大气,即日冕、过渡区和色球,是由炽热的高度动态的磁化等离子体构成,其中高度电离的离子发射出丰富的极紫外谱线。空间太阳极紫外光谱成像观测对于捕获太阳上层大气中爆发活动的动态物理演化过程,以及实现对大气等离子体特征参数的精确测量具有重要的意义。然而现有的极紫外光谱成像仪器只能针对太阳上层大气的一个或两个目标区域进行成像观测,缺乏采用单一仪器对整个太阳上层大气区域在大空间和宽波段尺度范围内的光谱进行诊断的能力,严重制约了人们对太阳爆发活动中的能量及物质输运过程的理解。为了利用单个仪器实现对日冕、过渡区和色球的高分辨率同时诊断观测,本文提出并设计了一款同时工作在17～21 nm、70～80 nm和95～105 nm三个波段的太阳极紫外成像光谱仪,该仪器基于非罗兰圆结构下的椭球面变线距（EVLS）光栅像差校正理论,采用狭缝扫描式成像光谱结构,实现了具有大离轴狭缝视场的高空间、高光谱分辨的消像散光谱成像。基于蒙特卡罗统计模拟方法对太阳极紫外三波段成像光谱仪的最优模型开展光线追迹仿真实验,仿真结果表明,所设计的成像光谱仪取得了良好的光栅像差校正效果,系统空间分辨率优于0.6″,光谱分辨率在1...     

基于双直角分束器的反射式静态傅里叶光谱仪光学系统

基于双直角分束器设计了一种反射式静态傅里叶变换光谱仪光学系统,并搭建了样机。该光谱仪光学系统的分光装置采用双直角分束器,其他光路全部采用反射式结构,有效折叠光路,与透射式静态傅里叶光谱仪相比,系统体积减小一半以上。用汞灯作为静态傅里叶光谱仪光源时,得到了404.7,435.8,546.1,577.0nm的峰值谱线,实验结果很好地复原了汞灯实际光谱;用波长为650nm的激光进行实验,光谱分辨率约为5.93nm,与理论计算结果基本相符。该光学系统具有结构紧凑、体积小、重量轻、抗震性强等诸多优点,可为小型化、便携式静态傅里叶光谱仪器的研制提供技术支持。     

高分辨傅里叶变换光谱技术在短波段光学中的应用及进展

讨论了傅里叶变换光谱技术向短波段光学扩展的必要性和主要技术难点,分别介绍了几种于紫外,真空紫外及软Ｘ射线波段的傅里叶变换光谱仪结构性能与原理,并进一步阐述了高分辨率傅里叶变换光谱仪在短波段光学中的应用。     

多维傅里叶变换光谱

二维或多维傅里叶变换谱的概念最早是在核磁共振(NMR) 谱学中提出的,随着激光技术 的发展,飞秒脉冲激光的实现使多维傅里叶变换谱的概念被引入到了光学领域,以脉冲激光代 替NMR 中的射频(RF) 场,激光波长从红外延伸到可见光波段。多维傅里叶变换光谱可以同时 提供的信息包括量子态上布居数以及量子态间的耦合,所以多维谱可以提供一维谱所无法获取的 反映量子系统演化动力学的信息,如量子系统中的能量转移以及分子间的相互作用等。人们使用 多维傅里叶变换光谱的方法对碱金属原子、量子阱、分子等量子系统中的动力学过程进行了一系 列的研究。     

高分辨率光谱仪线阵CCD采集系统设计

为了满足高分辨率光谱仪高灵敏度、高分辨率、低噪声的技术要求,设计了用于微光成像系统的背照式CCD驱动电路及主控电路。线阵CCD采集系统采用Altera公司的MAX X系列FPGA作为核心控制器件,为线阵CCD提供多路驱动信号;线阵CCD探测器输出模拟信号经过信号预处理及AD采样,变换为数字信号后通过USB接口模块发送给光谱仪。通过将线阵CCD采集系统安装到高分辨率光谱仪,对汞灯谱线进行特征峰测试,光谱分辨率可以达到0.062 nm,满足高分辨率光谱仪的探测要求。     

色散型光谱仪采样调制传递函数及对高斯型光谱谱线的影响

光电探测器参数的选择对色散型光谱仪性能具有重要影响,有必要对光谱仪中光电探测器的离散采样过程进行深入探讨.文章从频率域的角度出发,建立了采样模型,探讨了输入余弦信号的空间频率、光电探测器采样的像元宽度及像元的初始相位对采样结果的影响.引入取整函数,给出了统一的采样调制传递函数表达式,提出并计算了平均采样调制传递函数,消去了初始相位的影响,便于实际应用.对于色散型光谱仪光学系统产生的典型高斯型光谱谱线,将高斯谱线的傅里叶变换与平均采样调制传递函数相乘,得出了光谱仪整系统的调制传递函数表达式.在频率域分析了采样过程的平均混叠误差与空间频率的关系,研究了平均混叠误差极大值与高斯光谱谱线宽度的关系,并给出了要精确恢复谱线所需谱线宽度的阈值.该阈值对于光谱仪系统的光学参数选择有重要的参考意义.     

高分辨傅里叶变换激光腔内吸收光谱方法：原理和应用

介绍了使用连续扫描方式工作的傅里叶变换光谱仪来探测激光腔内吸收光谱的原理,并探讨了傅里叶变换激光腔内吸收光谱方法测量光谱谱线和强度的工作方式.通过对大气中水汽在12450—12700cm^-1波段的高分辨吸收光谱的实际测量,检验了该方法的可靠性,并使用该方法测量了重水分子(D₂O和HDO)ν_OD=5伸缩泛频态光谱. 关键词： 激光光谱 高分辨振转光谱     

新型傅里叶变换光谱仪反射镜倾斜容限分析及实验

采用微机电系统微镜阵列和倾斜反射镜替代传统傅里叶变换光谱仪的动镜系统,提出一种基于微机电系统微镜阵列的新型傅里叶变换光谱仪.介绍了该光谱仪的工作原理,分析了倾斜反射镜倾斜角度的容限范围,并搭建了实验系统,进行了实验验证.理论推导表明:在近红外区域,反射镜倾角理论最大值为0.52°,光谱分辨率达到8 nm;在可见光区域,反射镜倾角理论最大值0.183°,光谱分辨率达到3 nm.选取可见光源488 nm激光器进行的实验验证结果表明:在倾角容限范围之内,光谱能准确还原;反之,光谱严重失真.最终,采用复色光源进一步实验验证了理论分析的正确性.     

Studies of solar flares and CMEs related to the space solar missions in the future

Solar eruptions and the related processes involve magnetic fields and plasma flows of various scales in both time and space. These processes include the convective motions of the mass and magnetic field in the photosphere, evolutions of magnetic fields in both the chromosphere and the corona prior to and during the disruption of magnetic fields in response to the photospheric motions. These evolutions constitute a whole process of transporting the magnetic energy and the helicity from the photosphere to the corona, and then to interplanetary space. The present work, on the basis of a solar eruption model, discusses these processes, and the related questions, unanswerable at present, but could be the scientific objectives of the space solar missions in the future.     

精密气动液压伺服系统用于傅里叶变换光谱仪光谱测量

讨论了傅里叶变换光谱仪动镜稳定平移的重要性,研制了以高压无氧氮气为动力源的精密气动液压系统用于推进在研傅里叶变换光谱仪“猫眼”动镜系统,并在此基础之上测量了ＺＹＧＯ干涉仪光源光谱图。     

A high-resolution high-speed data acquisition system based on an IBM-PC 486, for control of a Fourier transform spectrometer

The mini-computer and control electronics of a Bruker 113v Fourier Transform Spectrometer (FTS), capable of 0.03 cm^–1 resolution for frequencies up to 4000cm^–1, have been replaced by an inexpensive IBM-PC 486-based system. The original performance is exceeded. JCAMP-DX standard is used for data exchange. The system can be adapted to any FTS or similar instrument which requires time domain data acquisition.     

利用空间外差光谱技术进行紫外高分辨率大气散射信号探测

羟基OH对于人类理解中间层化学成分非常重要,它是大气光化学反应中重要的氧化剂,OH在308 nm波段受到太阳能量激发,发射出OH A2Σ＋-X２Π（0,0）荧光信号。为了探测中间层大气中OH自由基的紫外共振荧光发射信号,从复杂背景信号中分离目标信号,研制了中高层大气OH自由基超分辨空间外差光谱仪,光谱范围为308.2～309.8 nm,光谱分辨率为0.008 25 nm。临边观测主要探测大气散射信号,能量来源为大气中的粒子,包括大气分子与气溶胶、云等对太阳能量的散射作用。中高层大气OH自由基超分辨空间外差光谱仪基于空间外差光谱技术,可以在设计的闪耀波长范围内获得极高的光谱分辨率,适用于大气成分的精细探测。通过在前置或后置光学系统中加入柱面镜,总视场内的场景被分成多个视场切片,每一个视场切片的干涉图分别成像到对应的探测器行上。利用空间外差光谱仪具有空间维分层成像功能,临边观测时可以同时获取不同高度层大气吸收光谱的散射辐射信号,无需像传统临边探测遥感器在不同高度层进行扫描来获取大气高度维的廓线信息。为了验证中高层大气OH自由基超分辨空间外差光谱仪的临边散射信号探测能力与对观测几何的敏感性,进行了地面临边观测实验,探测紫外308 nm波段大气散射信号。模拟临边观测几何,选取晴朗无云的一天,在空旷场地对大气散射信号进行观测。由于仪器基于空间外差光谱技术,需要对干涉数据进行干涉误差修正与光谱复原。对一段观测时间内间隔10分钟的干涉数据进行光谱复原并定标,得到最终临边观测光谱。由于散射信号的主要来源为大气分子对太阳光的散射作用,因此光谱中应包含太阳光谱高分辨率精细特征信息。从高分辨率太阳光谱中选取三个特征信息窗,分析观测光谱中对应波段,三个特征信息窗完全匹配,验证了中高层大气OH自由基超分辨空间外差光谱仪的超高分辨率光谱探测能力和光谱精细信息提取能力。将太阳辐射计实时测量获得的气溶胶光学厚度及根据观测时间计算的太阳天顶角与太阳方位角输入辐射传输模型SCIATRAN,结合对应日期与经纬度的大气廓线数据库,得到模拟光谱,将实测结果与辐射传输模型结果进行比对,两者残差较小。实测结果与模拟结果存在的残差,可能是由于大气环境参数并没有完全符合实测状态,后续可使用当地实时温湿压廓线对模拟数据库进行替换,使辐射传输模型更接近实际状态。与辐射传输模型对比的结果验证了中高层大气OH自由基超分辨空间外差光谱仪的散射信号探测能力与对观测几何的敏感性,验证了在轨探测多谱段、宽谱段大气散射光谱与OH目标信号的可行性,为在轨探测OH目标信号提供了理论与实验基础。     

Metamaterial-based frustum of cones array nanostructure for efficient absorber in the solar spectral band

Solar spectrum absorbing and harvesting are important for the utilization of solar energy. In this paper, we propose a metamaterial-based frustum of cones array solar energy absorber which appears an average absorptivity of 0.98 in the entire spectrum (i.e., 0.2–2.5 μm) with independent of the incoming light polarization state as well as the wide incident angle of as large as 50°. The efficient light harvesting property can be explained as the synergistic effect of the slow light mode, localized surface plasmon resonant effect and absorption induced by interband transition.     

The Detection of Defects in Optical Fibers Using a Hybrid Opto-electronic Correlator

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The Detection of Defects in Optical Fibers Using a Hybrid Opto-electronic Correlator

A hybrid opto-electronic correlator for detecting defects in optical fibers is proposed. After the light from a He-Ne laser being expanded and filtered it is not collimated but directly passes a Fourier transform lens and illuminates a reference fiber and a test fiber at the same input plane. The Fourier transform spectrum of the two fibers is therefore obtained at the rear focal plane of the lens, where it is sampled via a CCD array connected with a computer through a frame grabber. The computer performs filter, inverse Fourier transform and setting threshold operation on classification. The system is an equivalent of joint transform correlator with a Fourier lens of long focal length. The experiment results for optical fibers having incoordinate defects are presented. The results indicate that the system can be used for fiber defect detection, and has the advantages of high identification, compact configuration, easy adjustment and flexible manipulation.     

About the nature of <Superscript>3</Superscript>He isotope content increase in the region of 2.223 MeV gamma line generation in the period of solar flare

The intense solar flare on January 20, 2005 is studied based on the SONG-D/AVSF/ KORONAS-F data. The data on time profiles of the 2.223 MeV neutron line and narrow nuclear lines are involved in the analysis. Model calculations of neutrons propagating from their generation region in the corona to the neutron line formation region in the lower chromosphere and photosphere are performed. Coulomb energy losses of helium-3 ions in the case of their allowed acceleration in the flare are calculated. The increase in the relative ³He concentration during the flare is numerically analyzed. The study performed in combination with independent data on the helium-3 content in the flare region and helium-3 fluxes in interplanetary space lead to the conclusion that the acceleration region is the most probable immediate source of the increased content of accelerated helium-3 isotope ions.     

Vibration-rotation parameters for high-temperature silicon monoxide from sunspot spectra

Absorption features from vibrational transitions of silicon monoxide have been observed in sunspot umbrae between 1070 and 1225 cm^?1 using the Fourier transform spectrometer (FTS) at the McMath Solar Telescope of the National Solar Observatory, located at Kitt Peak. Sunspots are a source of high-temperature spectra not easily obtained in the laboratory. Measurements were made of 937 ²⁸SiO, ²⁹SiO, and ³⁰SiO fundamental and hot band transitions in the umbral spectrum extending to v = 10 and J = 80. All three isotopic species were treated together to derive 10 Dunham rotation-vibration coefficients.     

A nano-metallic-particles-based CMOS image sensor for DNA detection

In this paper we report on a study of the CMOS image sensor detection of DNA based on self-assembled nano-metallic particles, which are selectively deposited on the surface of the passive image sensor. The nano-metallic particles effectively block the optical radiation in the visible spectrum of ordinary light source. When such a technical method is applied to DNA detection, the requirement for a special UV light source in the most popular fluorescence is eliminated. The DNA detection methodology is tested on a CMOS sensor chip fabricated using a standard 0.5 μm CMOS process. It is demonstrated that the approach is highly selective to detecting even a signal-base mismatched DNA target with an extremely-low-concentration DNA sample down to 10 pM under an ordinary light source.