空间调制微型傅里叶变换红外光谱仪研究

针对目前环境、医疗、空间、气象、军事及安全等领域对傅里叶变换红外光谱仪微小型化、轻量化及固态化的迫切需求,提出并研究了一种以MOEMS多级微反射镜为核心器件的空间调制微型傅里叶变换红外光谱仪。在理论研究方面,建立了空间调制微型傅里叶变换红外光谱仪的物理模型,探究了该系统的光场分割与空间采样的光学原理;分析了多级微反射镜的衍射效应,提出了一种通过补边抑制衍射噪声抑制方法;进行了多级微反射镜采样误差的分析,并提出了基于最小二乘拟合的修正算法;通过对光源空间相干性、准直系统像差以及入射光场均匀性的分析,确定了光学系统的总体设计指标;通过对多级微反射镜基片加工精度、分束器材料色散特性和膜层透射效率等的计算分析,确定了干涉系统的设计方法与技术参数。在核心技术方面,提出了两个多级微反射镜的3种制作方法,分析了制作误差的来源及对系统性能的影响。通过工艺设计及实验条件探索,分别采用电铸法、真空镀膜法以及斜面倾角叠片法制作了两个多级微反射镜。在系统设计方面,进行了红外准直与缩束系统的光学设计,对整体光机系统进行了建模仿真,分析了杂散光噪声的来源。在图谱处理方面,利用过零采样方式,通过图像分割算法,获取了干涉图采样序列;通过对干涉图序列的插值、补零、延拓与卷积方法,完成了光谱相位误差的校正;通过离散傅里叶变换解调,实现了由干涉图像到信号光谱的数据反演。最后研究了系统光机整体的集成组装技术,并对原理样机进行了实验测试。本文研制的空间调制微型傅里叶变换红外光谱仪的特点在于:取消了动镜驱动机构与采样控制机构,具有微小型与轻量化的特点;干涉图的采样由多级微反射镜完成,其空间采样的方式增加了系统的稳定性与可靠性,实时采样的特点增加了系统的快速性与有效性;多级微反射镜阵列采用MOEMS工艺技术制作,增加了系统的采样精度。该光谱仪系统的结构及制作方法具有自主知识产权,并具有广阔的应用前景。     

Fourier transform emission spectroscopy of YbO in the near-infrared region

The emission spectrum of gas-phase YbO has been investigated using a Fourier transform spectrometer. Chemiluminescence was observed from excited YbO molecules produced in a Broida-type oven by the reaction of ytterbium metal vapor with N₂O. A total of eight red-degraded bands in the range 9800-11 300 cm⁻¹ were recorded at a resolution of 0.04 cm⁻¹. Because of the multiple isotopomers present in the spectra, only three bands were rotationally analyzed. Perturbations were identified in two of these bands and all three transitions were found to terminate at the X1Σ+ ground electronic state. The electronic configurations that give rise to the observed states are discussed and molecular parameters for all of the analyzed bands are reported.     

中波红外微型静态傅里叶变换光谱仪的设计与分析

提出一种基于微光学元件的空间调制微型傅里叶变换红外光谱仪,通过引入红外微结构衍射光学元件、多级微反射镜和微透镜阵列,实现仪器的微型化.介绍了微型傅里叶变换红外光谱仪的结构及基本原理,分析了微型准直系统和聚焦耦合光学系统的设计理论,研究了单片折衍混合准直透镜的残存像差、衍射面的衍射效率、多级微反射镜的衍射、微透镜阵列的孔径衍射和中继系统的轴向装配误差对光谱复原的影响.最后,对中波红外微型傅里叶变换光谱仪进行了建模仿真,得到的复原光谱与理想的光谱曲线比较符合,实际的光谱复原误差为2.89%.该中波红外微型静态傅里叶变换光谱仪无可动部件,且采用了微光学元件取代了传统的红外镜头,不仅稳定性良好,而且体积小、重量轻,有利于在线监测应用.     

利用开放光路傅里叶变换红外方法监测地表臭氧含量及分析

基于自研傅里叶变换红外光谱仪设计实现了开放光路臭氧在线监测系统,将计算机合成背景光谱方法与非线性最小二乘方法相结合进行定量分析,利用HITRAN数据库信息和仪器线型合成背景光谱,通过非线性最小二乘法反演出臭氧浓度,提高了测量精度和检测限,讨论了系统检测限测最方法,在16次平均情况下系统检测限达到1.42 nmol·mo...     

Laser and Fourier transform emission spectroscopy of TaCl

The emission spectrum of TaCl has been recorded at high resolution in the 3000-35 000 cm⁻¹ region using a Fourier transform spectrometer. The bands were observed by microwave excitation of a mixture of TaCl₅ vapor and 3.0 Torr of He. Several TaCl bands have also been recorded using the laser ablation/molecular beam source at the University of New Brunswick. A rotational analysis of a number of bands has been obtained and the majority of the stronger bands have been classified into three groups with different lower state spectroscopic constants. The three lower states have been identified as having Ω″ = 0⁺, Ω″ = 2, and (tentatively) Ω″ = 3. The Ω″ = 0⁺ and Ω″ = 2 states are very close in energy and one of these two states is the ground state of TaCl.     

Field-compensated birefringent Fourier transform spectrometer

A field-compensation method applied for Savart birefringent Fourier transform spectrometer is presented. By using a combination of Savart plates fabricated from positive and negative birefringent materials, the useful solid angle of field of view can be increased by a large amount in broad spectral coverage. Compared to the conventional Fourier transform spectrometers, the compensated field angle has optical throughput higher by one order in magnitude. To demonstrate the effectiveness, a design example operating at 400-1100 nm with a large solid angle exceeding ± 40° is presented in detail.     

基于多级微反射镜的傅里叶变换红外光谱仪中准直误差的分析

通过对基于多级微反射镜的空间调制傅里叶变换红外光谱仪准直误差的分析,模拟了准直误差的存在而导致的干涉图大光程差处对比度反转和光谱图边频噪声的产生。讨论了在不同的误差系数下复原光谱图的信噪比和分辨率,并且分析了干涉图大光程差处对比反转以及光谱图边频分量的产生原因。仿真结果表明,在误差系数α=0.15°.mm-1时,光谱的信噪比会下降到6 dB,同时光谱分辨率会退化到13.4cm-1。本文的结论将应用于微型光谱仪系统的光学设计与装调。     

傅里叶变换实时红外光谱复原的FPGA实现

为实时获取战场激光、大气污染物气体、毒气等待测物光谱信息的光谱复原,设计了基于现场可编程门阵列(FPGA) 的实时光谱采集分析系统。该系统选用迈克尔逊干涉具和碲镉汞探测器获取待测光谱信息,将采集到的数据传入FPGA。利用硬件描述语言VerilogHDL在Xilinx FPGA芯片上依据傅里叶变换(FFT)实现干涉条纹到光谱数据的实时处理。实验结果表明,FPGA实际计算1 024点基2-FFT频谱分布信息与Matlab理论计算结果相同,可满足实时光谱探测的要求。     

高分辨率傅里叶变换成像光谱仪光谱重建并行算法

高分辨率傅里叶变换成像光谱仪具有高空间分辨率和高光谱分辨率的特点,但光谱重建时间冗长。通过对傅里叶变换光谱重建流程分析,为研制的1024pixel(光谱维)×1024piexl(像宽)×1024piexl(像高)高分辨率紫外傅里叶变换成像光谱仪的数据立方体反演,设计了一种并行优化算法。实验表明,在6核处理器上对512M和2G的数据立方体进行变换,时间分别只需88.33s和489.75s,加速比分别为3.70和3.04,大幅度提高了运算效率。如将该算法应用到更多内核处理器上,可得到更高的加速比和更少的运算时间。     

Fourier transform emission spectroscopy of the BΣ-XΣ system of CN

The emission spectrum of the B²Σ⁺-X²Σ⁺ system of CN has been observed at high-resolution using a Fourier transform spectrometer. The rotational structure of a large number of bands involving vibrational levels v = 0-15 of both electronic states has been analyzed, and improved spectroscopic constants have been determined by combining the microwave and infrared measurements from previous studies. Improved spectroscopic constants for vibrational levels up to v″ = 18 in the X²Σ⁺ state and v′ = 19 in the B²Σ⁺ state have been determined by combining the measurements of the 16-13, 18-17, 18-18, 19-15, and 19-18 bands of Douglas and Routly [Astrophys. J. Suppl. 1 (1955) 295-318] and 17-14 and 17-16 bands of Ito et al. [J. Chem. Phys. 96 (1992) 4195] with our data. The band constants obtained have been used to estimate equilibrium ground state constants for CN.     

Frictionless mirror drive for intermediate resolution infrared Fourier transform spectroscopy

A simple and compact parallelogram mirror drive based on flexure pivots suitable for intermediate resolution Fourier transform spectroscopy is presented. The system permits 12 mm of mirror translation with a residual tilt of less than ±0.4 mrad in the horizontal plane and ±0.2 mrad in the vertical plane. A system prototype was built and fully characterized for a Fourier transform spectrometer operating on a stratospheric balloon.     

全反射式高分辨率傅里叶成像光谱仪的研究

提出了一种基于分波前干涉结构的全反射式高分辨率傅里叶变换成像光谱仪。其中前置望远系统及干涉成像系统都采用了反射式光学元件,反射表面镀金属反射膜,使系统可应用与很宽的光谱范围内。分析和讨论了光谱仪的工作原理及光学结构,设计了两种可行的光路结构图,并通过初步实验验证了系统的基本性能。     

窗扫型成像光谱仪数据处理及误差校正研究

窗扫型傅里叶变换成像光谱仪具有高光通量和无动镜等特点,同时也增加了数据处理的难度,需要对采集的原始干涉图进行重组。通过对其数据处理流程特点的分析,设计了一种归一化算法,对由干涉图重组时产生的误差进行了校正,并对在数据采集过程中干涉图的中心暗纹位置的采样误差进行了二次曲线拟合校正。整个数据处理过程实现了从干涉数据立方体到光谱数据立方体的变换。从理论分析和实验结果的比较中验证了误差校正方法的有效性。     

SiO2纳米线簇、C-Si-O纳米球的制备及形貌、红外光谱和光致发光光谱研究

以二茂铁和硅油作为催化剂和原料,利用高温裂解硅油为C,Si,O源,在常压N₂和H₂混合气氛的化学气相沉积管式炉中制备了大量直径为5—40 nm、长数百纳米的非晶SiO₂纳米线簇及粒径为100—300 nm的C-Si-O实心纳米球. 利用透射电子显微镜、扫描电子显微镜对产物形貌进行表征.Fourier红外吸收谱显示出非晶SiO₂所具有的474,802和1100 cm^-1三个特征峰;SiO₂纳米线簇的光致发光光谱具有较强440 nm蓝光发光峰;而C-Si-O（原子数之比为1.13∶1∶2.35）纳米球具有奇特的红绿蓝（625,540,466 nm）三色光致发光谱. 关键词： 2纳米线簇')" href="#">SiO₂纳米线簇 C-Si-O纳米球 高温裂解 Fourier红外谱     

激光单稳频指标的激光计量红外光谱仪精度分析

在傅里叶变换红外光谱仪中,采用激光计量光程差可提高光谱的测量精度。激光波长作为光程差测量的基准单位,其线宽和稳频特性直接决定了光程差的误差,进而影响光谱的测量精度。根据光谱仪的干涉原理,通过傅里叶逆变换和误差分析方法,建立了光谱测量相对误差与激光单稳频指标之间的理论模型,并对该模型进行了仿真计算。结果证明,该模型可作为设计激光计量光程差光谱仪系统的理论依据。     

Near infrared emission spectra of CoH and CoD

New high resolution emission spectra of CoH and CoD molecules have been recorded in the 640 nm to 3.5 μm region using a Fourier transform spectrometer. The bands were excited in a carbon tube furnace by the reaction of cobalt metal vapor and a mixture of H₂ or D₂ with He at a temperature of about 2600 °C. Eight bands were observed for the A′³Φ₄-X³Φ₄ electronic transition of CoD, and five bands for the corresponding transition of CoH. The (0, 0) bands of the A′³Φ₃-X³Φ₃ system were also recorded for both isotopologues, although one of the parity components in the X³Φ₃ sub-state of CoH was found to be perturbed. The A′³Φ₃-X³Φ₄ transition was also observed in our spectrum of CoH. In addition, a new [13.3]4 electronic state was found by observing [13.3]4-X³Φ₃ and [13.3]4-X³Φ₄ transitions in the spectrum of CoD. Analysis of the transitions with ΔΩ = 0, ± 1 provided more accurate values of spin-orbit splittings between Ω = 4 and Ω = 3 components. The ground-state data for both molecules were fitted both to band-constant and Dunham-expansion expressions, and a combined-isotopologue analysis of the X³Φ₄ spin component was carried out using the data for CoH and CoD. The upper states were represented by term values in these analyses because of perturbations, but estimated band constants for them were obtained in separate fits in which ground-state constants were held fixed.     

Fourier transform emission spectroscopy and ab initio calculations on NbCl

The emission spectrum of NbCl has been recorded in the 3000-20 000 cm⁻¹ region using a Fourier transform spectrometer. The bands were observed by microwave excitation of a mixture of NbCl₅ vapor and He. Two groups of bands observed in the 6500-7000 cm⁻¹ and 9800-11 000 cm⁻¹ regions have been assigned to two electronic transitions. Five bands observed in the 6500-7000 cm⁻¹ region consist of R, P, and Q branches with no combination defect or Λ-doubling. They have been assigned as five sub-bands of a ΔΛ=±1 transition with Λ>1. Nine bands observed in the 9800-11 000 cm⁻¹ regions consist of R and P branches, and they are also free from Λ-doubling. These bands have been classified into four sub-bands of a ΔΛ=0 transition (with Λ>1), which has tentatively been assigned as . The two transitions have no electronic states in common. Ab initio calculations have been performed on NbCl and the spectroscopic properties of the low-lying electronic states have been calculated. The ground state of NbCl has been predicted to be a state arising from the 3σ¹ 1δ² 2π¹ configuration, with a low-lying state at 1300 cm⁻¹ from the 3σ¹ 1δ¹ 2π² configuration. The results of our experimental and theoretical studies will be presented. This work represents the first experimental investigation of the spectra of NbCl and the first ab initio prediction of the spectroscopic properties of the low-lying electronic states.     

非对等FOV作用下的高分辨率FTIRS仪器线型函数研究

视场角(FOV)是仅次于最大光程差、决定高分辨率傅里叶红外光谱仪(FTIRS)仪器线型函数(ILS)的重要因素.由于光学设计和装调原因,理论为圆形FOV的扩散光束,到达探测器端时,其水平和垂直方向上的FOV值往往不再严格对等.对此,提出了以椭圆形面光源取代传统文献中的圆形面光源来反映这种非对等性,并结合最大光程差参数,...     

Molecular beam millimeter sidebands Fourier transform spectrometer (MB-MMSBFT)

The high resolution Fourier transform technique has been extensively applied in the centimeter range. In the past few years great progress have been made in observing molecular complexes. Most instruments operate between 2 and 26 GHz. So, very light interesting molecular species cannot be observed. The extension of the method towards the millimeter range suffers important technological shortcomings. A sidebands generation technic allowing the generation of very short pulses, all over the millimeter wave range, is described. For the first time, the experiment is performed in a resonant cavity and on a supersonic nozzle beam.