微型MOEMS阿达玛变换近红外光谱仪

提出一种运用微光机电系统(micro-opto-electro-mechanical systems,MOEMS)闪耀光栅,动态产生阿达玛变换模版的微型近红外光谱仪.它具有体积小、价格低、扫描速度快等突出优点.分析了这种新型近红外光谱仪的结构和工作原理,通过对MOEMS闪耀光栅编程,动态生成了 63阶阿达玛模版.实验得...     

基于数字微镜技术的阿达玛变换近红外光谱仪

构建了一个基于数字微镜技术的新型阿达玛变换近红外光谱仪.光学信号采用光纤引入,以光栅作为分光元件,利用数字微镜代替传统的机械式阿达玛模板进行光学编码调制,使用单点InGaAs红外探测器检测调制后的光信号,通过快速阿达玛解码还原出原始光谱.通过实验检验了光谱仪的分辨率、信噪比、稳定性以及谱图获取速度等指标.实验结果表明,...     

静态双增益阿达玛光谱仪光谱的重叠错位分析与校正

为平衡光栅色散型光谱仪光通量、系统信噪比和光谱分辨率之间的矛盾,介绍了一种基于微狭缝阵列的静态双增益阿达玛光谱仪.在分析其实现静态双增益工作原理的基础上,阐述了由于阿达玛编码模板多狭缝阵列引起的光谱重叠的原因.为实现静态双增益阿达玛光谱仪光谱重叠校正,理论推导了光谱偏移量与阿达玛编码模板狭缝空间位置之间的关系,以及分光后某波长空间错位量与码元(狭缝)空间位置、波长之间的关系.仿真实验验证了此方法简单有效,无需复杂计算,修正速度快,易于编程实现.     

空间调制干涉型阿达玛变换光谱成像仪

简要叙述了色散型阿达玛变换光谱成像仪的原理及仪器构成,指出其存在空间信息与光谱信息的错位和光谱分辨率受阿达玛编码模板码元宽度制约的缺陷.提出空间调制干涉型阿达玛变换光谱成像技术原理及仪器,利用横向剪切干涉仪获得所有阿达玛编码光信息在不同光程差处的干涉信号,对干涉谱进行傅哩叶变换和阿达玛变换得到目标的光谱.理论分析表明,干涉图的调制度不受阿达玛模板形状、大小等因素的影响,光谱分辨率与阿达玛模板的尺寸无关,不但避免了色散型阿达玛变换光谱成像仪中空间信息和光谱信息的错位,而且高能量通过率、高空间分辨率和高光谱分辨率成像容易同时实现.     

基于DMD的哈达玛变换成像光谱仪中交错编码像素点的研究

近年来在哈达玛变换成像光谱仪研究领域中最重要的技术革新在于数字微镜器件在这种光谱仪中的应用,但同时也带来了一些相应的技术问题需要克服。详细的描述和分析了由于数字微镜器件在哈达玛变换光谱仪中的应用导致的编码图像上的部分像素点出现的一种交错编码现象;这种特殊的像素点,编码过程不符合哈达玛变换,在光谱复原过程中需要特殊处理。针对这种交错编码像素点,提出了一种标识方法和解码方法。实验中,向光谱仪中导入一束激光并充满整个视场,在编码的激光图像中确定交错编码像素点的位置。然后变换编码模板上哈达玛编码码道的空间位置,采集两组针对目标的编码图像,通过观察编码图像上一个像素点的灰度值组成的列向量中非零常量与零元素的个数,可以分辨它是否是一个交错编码像素点。其中一组编码图像上交错编码像素点光谱曲线可以通过对另一组编码图像上相应位置的像素点进行哈达玛反变换得到。实线结果证明了这一方法的可行性。     

基于阿达玛变换提高激光告警系统信噪比的研究

根据阿达玛变换原理,计算了编码模板大小和码元数,详细介绍了Sn循环矩阵的生成,最后选择数字微镜阵列充当编码模板,并进行了仿真实验研究。实验结果表明,将阿达玛变换应用于激光光谱测量,在不增加测量次数的情况下,可以有效地提高系统的信噪比。     

面向生物过程的阿达玛变换近红外光谱仪

对生物过程中营养物质的消耗进行监测,有利于控制微生物的生长环境,使其始终处于最佳生长条件,从而使目标产物的产量最大化。针对酵母培养液中甘油、甲醇和葡萄糖含量的监测需求,研制了一种基于阿达玛变换(hadamard transform,HT)技术的近红外光谱仪。该光谱仪使用自主改进设计的近红外原位探头进行光谱信号的收集,采用数字微镜(digital micro-mirror devices,DMD)进行阿达玛模板的编码调制,配合自主开发的光谱采集软件和光谱分析处理软件,实现了培养液中营养物含量的实时监测。给出了光谱仪的光路设计、近红外原位探头改进设计、硬件电路和软件模块的设计。通过实验测得该光谱仪的杂散光为0.875%,波动率为±4.28%。利用该光谱仪对一系列标准浓度的甘油水溶液进行光谱采集和数学建模,实验结果表明该仪器测量准确,能够满足生物过程监测的要求。     

数字微镜哈达玛光谱仪谱线弯曲的分析与修正

由于数字微镜（digital micro-mirror device, DMD)哈达玛变换光谱仪其成本低,光能利用率高及无运动部件等优势,逐渐成为光谱仪领域的研究重点。研制了一款基于DMD的哈达玛变换光谱仪。为了解决光谱仪谱线弯曲造成的光谱分辨率下降的问题,对基于DMD的哈达玛变换光谱仪中的谱线弯曲所引起的谱带混叠进行了分析。首先,导出了谱带混叠与谱线弯曲的关系式。然后,提出了两个过程来解决谱带混叠,一是通过调整DMD编码条纹,使DMD所编码的谱带最大限度地与标准谱带重合; 二是通过数据处理对谱带混叠进行修正。最后,通过对谱线曲率半径为5.8×104,7.8×104和9.7×104 μm等六种情况下谱带混叠进行了分析与修正,拟合出光谱混叠和修正效果与谱线曲率半径的关系。结果表明： 对于不同程度的谱线弯曲经过这两个过程修正后,分辨率都会改善到接近光学系统的分辨率, 说明这两个过程对修正谱线弯曲具有普适性、并且方法简单、有效。     

A double pass rapid scanning Fourier transform spectrometer for plasma diagnostics

The construction and the performance of a double pass rapid scanning Fourier transform spectrometer are described. The instrument covers a frequency range below 900 GHz. It has a maximum spectral resolution of 6.6 GHz and a maximum time resolution of 10 msec. The spectrometer has been applied to JIPP T-II device at Institute of Plasma Physics in Nagoya University. Electron cyclotron emission from the device has been measured and the electron temperature of the plasma has been obtained. The results are shown.     

Single-shot two-dimensional spectrometer

A two-dimensional optical spectrometer is demonstrated using simple optical components. This spectrometer is based on ultrafast two-dimensional (2D) frequency-dispersed pump-probe spectroscopy and can be used for single-shot correlation spectroscopy. To demonstrate functionality of this device, we measure the 2D correlation spectrum of atomic rubidium.     

教学用自组式傅里叶变换光谱仪

对原有的傅里叶变换光谱实验进行了全面的升级改造，研制了一种新型的教学用自组式傅里叶变换光谱仪，波长精度较原有实验提高了两个数量级，由该仪器构成的傅里叶变换光谱实验内涵丰富，不但可以使学生学习一种重要的光谱技术，更可以很好地培养学生综合运用所学知识解决实际问题的能力。     

Transparent Fourier transform spectrometer

We realized a transparent Fourier transform spectrometer and investigated its operating principle. The spectrometer consists of a low-reflectivity Fabry-Perot interferometer and a partially transparent photodetector, which allows for the operation of the spectrometer in transmission. By changing the distance between the low-reflectivity mirrors of the Fabry-Perot interferometer, the light intensity that reaches the partially transparent photodetector is modulated and the spectral information of the incident light is determined by the Fourier transform of the generated photocurrent. This transparent Fourier transform spectrometer allows easy miniaturization and integration into any kind of optical system.     

Fourier transform emission lifetime spectrometer

We report a rapid and low cost Fourier transform spectrometer that uses a path length modulated Michelson interferometer to simultaneously measure excitation spectra and excitation wavelength-dependent emission lifetimes. Excitation spectra and lifetimes of excited tris(2,2'-bipyridyl) ruthenium(II) measured using this technique corresponded to values known in the literature. Excitation-dependent lifetimes of porous silicon measured with this technique suggest the influence of quantum confinement effects. This method may be useful for measuring mixtures of emitting species with closely spaced lifetimes as well as studying excitation wavelength-dependent emission phenomena.     

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.     

A Fourier transform Raman spectrometer with visible laser excitation

We present the development and performance of a Fourier transformation (FT)‐based Raman spectrometer working with visible laser (532 nm) excitation. It is generally thought that FT‐Raman spectrometers are not viable in the visible range where shot noise limits the detector performance and therein they are outperformed by grating based, dispersive ones. We show that contrary to this common belief, the recent advances of high‐performance interference filters makes the FT‐Raman design a valid alternative to dispersive Raman spectrometers for samples which do not luminesce. We critically compare the performance of our spectrometer to two dispersive ones: a home‐built single channel and a state‐of‐the‐art charge coupled device‐based instruments. We demonstrate a similar or even better sensitivity than the charge coupled device‐based dispersive spectrometer particularly when the laser power density is considered. The instrument possesses all the known advantages of the FT principle of spectral accuracy, high throughput, and economic design. We also discuss the general considerations, which helps the community reassess the utility of the different Raman spectrometer designs. Copyright © 2015 John Wiley & Sons, Ltd.     

实用宽带高分辨率声表面波线性调频变换功率谱仪

声表面波(SAW)线性调频变换(CZT)技术是实时傅利叶变换处理的主要支持性技术之一。其实用化研究始于七十年代末。本文将介绍作者以射电天文望远镜为直接应用对象,所研制的SKP-1型宽带高分辨率SAW功率谱仪。其中着重介绍一种扩展CZT变换器固有50%有效工作周期的新方法。并给出谱仪实验室测量的详细性能。