远红外自由电子激光器的性能和可能的应用(英文)

本文提出了远红外自由电子激光器(FIRFEL)的现实优点:对电子束质量要求不太苛刻;比较经济;对远红外区的非线性和相干性研究是唯一的合适的光源。分析了自由电子激光器增益与电子束和摆动器参量的关系,指出对给定的发射度存在一特定的波长,当波长比特定波长短时,增益将急骤下降。概述了远红外区的重要物理现象以及远红外自由电子激光器的可能的应用,预期这些研究对THz电子学发展是很重要的。     

远红外自由电子激光太赫兹光源研究

基于射频电子直线加速器的可调谐相干太赫兹(THZ)光源实现了出光，该光源为远红外自由电子激光，具有辐射波长可设计并可以实现大范围调谐特性．利用光栅谱仪测量了受激辐射谱，中心波长为115μm，谱宽约为1％．     

利用FEL康普顿背散射实现对NSRL辐射波段的扩展

 针对NSRL同步辐射光源不能开展硬X射线领域实验研究的缺点,提出了利用FEL康普顿背散射产生高亮度极化的硬X射线,并利用FEL波长可调的特点来连续调节硬X射线的波长。同时还针对NSRL光源的参数,提出了一个初步可行的远红外FEL参数和背散射工作方式,并给出了理论结果。     

太赫兹科学与技术研究回顾

太赫兹光谱系统利用远红外辐射获得分子的某些光谱信息，这些信息在电磁谱的其他波段中是很难得到的．材料的研究是现代太赫兹系统中的重要的组成部分，一方面因为新的、大功率的太赫兹光源极大地依赖于如量子级联结构一类的新材料；另一方面，太赫兹的光谱和成像技术也为扩展诸如半导体和生物有机分子等材料的应用提供了一个有力的工具．     

我国第一台太赫兹光源出光

经过长达8年坚持不懈的努力，中国工程物理研究院基于射频直线加速器技术的远红外自由电子激光（FIR-FEL）实验取得突破性进展，于2005年3月24日晚8时30分首次出光，并多次重复．中心波长115μm，谱宽1％．这标志着我国第一个可调谐相干太赫兹（THz）光源建成出光，填补了国内空白，是我国新型激光技术领域一个具有里程碑意义的重要成果．     

浅谈远红外技术的应用发展

 远红外频段属于正在开拓的电磁波段,至今仍是基础研究的热点。但是,正如科学发展的历史所表明的,任何一个电磁波段的开发,都会促进技术的发展,并造福人类。远红外的发展应用也不例外。激光作为远红外相干辐射源,频率覆盖面宽、结构简单、频线丰富、投资较少,因此光泵远红外激光的应用较多。迄今为止,远红外技术在下面各个领域不断发展。一、远红外激光远红外激光很多都是用于军事和国防领域,因此各国对此技术的公开均采取谨慎态度,外界了解不多。     

利用光电流光谱进行脉冲染料激光器波长绝对标定

可调谐激光器取代通用的波长选择元件(如单色仪或干涉仪),作为连续可调谐的单色光源与光学混频技术相结合,能够提供从真空紫外到远红外的宽阔光谱范围内的强光源,为研究原子、分子、固体和等离子体的结构提供了许多新的可能性。因此,可调谐激光器目前广泛地应用在物理、化学、     

会议消息

据《照明学会杂志》1974年第2号报导,日本照明学会全国大会定于4月4、5两日召开。会上报告的内容,在光源、器件和材料方面有:远红外灯的特性、超细型荧光灯、用放射性同位素考察荧光灯发生黑化的机理、低压氙气放电引起的荧光体发光、投影用的金属卤化物灯,使用液     

光功率调节器

光电发展部正在开发光功率调节器。这种调节器控制光功率的精度很高,可用于探测器校准、干涉测量以及要求高精度读数的测量。光功率调节器还可以在几秒、几小时和几天时间内提供高精度的强度控制,并能够在紫外到远红外波长范围内工作。它可采用激光和白炽灯光源,并能在各种功率和孔径范围内使用。     

准相位匹配技术

常用激光器输出波长通常为近红外单一频率的激光,随着科技的发展,各行各业对激光器的需求大大增加,对激光器输出波长提出了更高要求,不但要求输出波长向红外和紫外扩展,而且输出波长要连续可调谐。通过非线性频率变换可以获得普通激光器达不到的输出激光波长,如紫外、中红外和远红外激光等,并且输出激光波长可以在一定范围内变化（即可调谐）,如1～3微米、3～5微米和8～13微米等,这三个重要波段的红外相干光源在光谱研究、激光制导、激光定向红外干扰、大气监测等领域有广泛应用。     

基于红外光谱技术的混合气体检测系统概述

为了给从事红外混合气体检测领域的研究人员提供一定的借鉴与参考,针对红外混合气体检测系统中的光学复用结构以及检测方法进行了详细评述。目前,以量子级联激光器(QCL)、带间级联激光器(ICL)为代表的相干光源已逐渐取代热辐射红外光源、红外发光二极管(LED)等传统非相干光源,成为红外混合气体检测中的主流光源。相应地,具有超高探测度和极短响应时间的红外光探测器也逐渐超越以往的红外热探测器,占据红外探测器领域的主导地位。基于“复用思想”的光学复用结构则是红外混合气体检测系统的核心,主要包括单光源复用检测结构和多光源复用检测结构。其中,单光源复用检测结构以其体积小、集成度高等优点成为构建便携式混合气体检测系统的重要选择;而多光源复用检测结构是时分复用、频分复用、波分复用等思想的具体化,并凭借其较宽的光谱覆盖范围、较高的光谱分辨率等优势成为当前混合气体检测系统中的主导结构。应用于红外混合气体检测的检测方法主要有非分光红外(NDIR)光谱技术、波长/频率调制光谱技术、腔增强光谱技术以及光声光谱技术等。研究人员可通过对红外混合气体检测系统各组成部分充分了解后,设计出实用的红外混合气体检测系统,对工农业生产、环境监测、生命科学等诸多领域都具有重要意义。     

Magnetic and Desorption Cryogenic Calorimeters as Supersensitive Detectors of Far IR Radiation

In this work, we estimate the potential of a cryogenic far IR radiation detector for registering the energy release by the amount of a substance desorbed upon its exposure to far IR quanta. The temperature invariability of the system at the first-order phase transition excludes the diffusion character of heat transfer processes, which contributes to the detector’s speed of operation and, according to our estimates, enables its use in pulsed location systems based on a CO₂ TEA laser. As an example of another cryogenic detector, we consider an antiferromagnetic, where the speed of operation is provided by the resonance transfer of far IR quantum energy to the spin system, the sublevels of which are split by a strong (～1,000 T) exchange field. The magnetic response arising in this case is registered by a quantum magnetometer based on the Josephson effect.     

Source characterization using recordings made in a reverberant underwater channel

The ability to accurately characterize an underwater sound source is an important prerequisite for many applications including detection, classification, monitoring and mitigation. Unfortunately, anechoic underwater recording environments required to make ideal recordings are generally not available. This paper presents a practical approach to source characterization when working in an imperfect recording environment; the source spectrum is obtained by equalizing the recording with the inverse of the channel’s impulse response (IR). An experiment was conducted in a diving well (depth of 5.18 m) using a logarithmic chirp to obtain the IR. IR length is estimated using methods borrowed from room acoustics and inversion of non-minimum phase IR is accomplished separately in the time and frequency domain to allow for a direct comparison. Results indicate that the energy of controlled sources can be recovered with root-mean-square error of −70 dB (10–70 kHz band). Two equations, one coherent and the other incoherent, are presented to calculate source spectral levels of an unknown source in a reverberant environment. This paper introduces a practical procedure outlining steps to obtain an anechoic estimate of an unknown source using equipment generally available in an acoustic laboratory.     

光学读出红外成像中面光源影响下的光学检测灵敏度研究

在光学读出红外成像的理论分析中, 通常将具有一定实际尺寸的非相干面光源简化为理想点光源, 导致了分析误差. 本文建立了面光源模型, 通过夫琅禾费衍射理论, 研究了面光源影响下的光学检测灵敏度, 发现了光学检测灵敏度随光源半径和焦平面阵列反光板长度的变化关系, 提出了面光源影响下的光源尺寸和反光板长度的优化设计准则. 针对理论分析, 进行了实验验证, 测试结果与理论分析一致. 关键词： 面光源 光学读出 焦平面阵列 非制冷红外成像     

Heat source reconstruction from noisy temperature fields using a gradient anisotropic diffusion filter

This paper presents a post-processing technique for noisy temperature maps based on a gradient anisotropic diffusion (GAD) filter in the context of heat source reconstruction. The aim is to reconstruct heat source maps from temperature maps measured using infrared (IR) thermography. Synthetic temperature fields corrupted by added noise are first considered. The GAD filter, which relies on a diffusion process, is optimized to retrieve as well as possible a heat source concentration in a two-dimensional plate. The influence of the dimensions and the intensity of the heat source concentration are discussed. The results obtained are also compared with two other types of filters: averaging filter and Gaussian derivative filter. The second part of this study presents an application for experimental temperature maps measured with an IR camera. The results demonstrate the relevancy of the GAD filter in extracting heat sources from noisy temperature fields.     

外场用红外目标模拟器辐射特性测量研究

野外便携式红外目标模拟器作为红外目标辐射源,广泛应用于各军兵种武器装备的效能测试评估中.针对外场模拟辐射源不能精确标定的问题,采用标准面源黑体和红外傅里叶光谱辐射计相结合标定的方法,对红外模拟器特定温度下的光谱辐亮度进行测量,计算出感兴趣波段的积分辐亮度,根据模拟器辐射面积给出用户需要的模拟器各设定温度下的辐射强度.分析计算表明:计算出的感兴趣波段的积分辐亮度值和理论曲线相比较,取得了良好的一致性,间接验证了该方法的正确性.     

Optimized IR synchrotron beamline design

Synchrotron infrared beamlines are powerful tools on which to perform spectroscopy on microscopic length scales but require working with large bending‐magnet source apertures in order to provide intense photon beams to the experiments. Many infrared beamlines use a single toroidal‐shaped mirror to focus the source emission which generates, for large apertures, beams with significant geometrical aberrations resulting from the shape of the source and the beamline optics. In this paper, an optical layout optimized for synchrotron infrared beamlines, that removes almost totally the geometrical aberrations of the source, is presented and analyzed. This layout is already operational on the IR beamline of the Brazilian synchrotron. An infrared beamline design based on a SOLEIL bending‐magnet source is given as an example, which could be useful for future IR beamline improvements at this facility.     

Exploring the potential of applying infrared vibrational (micro)spectroscopy in ergot alkaloids determination: Techniques,current status,and challenges

Ergot alkaloids (EA) are toxins produced mainly by Claviceps fungi and are considered as one of the most important groups of mycotoxins. Rapid and reliable detection techniques are urgently required by producers, importers and market regulators. As a promising alternative to conventional wet chemistry, infrared (IR)-based techniques are non-destructive, rapid and cost-effective. However, very limited studies on the qualitative or quantitative analysis of ergot or EA in food or feed based on IR vibrational spectroscopy have been reported so far. Being a secondary technique, the accuracy of IR method heavily depends on the robustness of chemometrics models. This paper aims to offer a brief overview of the EA issue in food and feed, conventional detection methods, theoretical principles of IR-based techniques and commonly used chemometrics for spectral data processing. In addition, the current application status of IR spectroscopy in ergot research is also considered.     

The influence of optical properties of paints and coatings on the efficiency of infrared nondestructive testing applied to aluminum aircraft structures

IR NDT (Infrared Nondestructive Testing) is a popular method for detecting defects in composite, ceramic, and metallic structures. The effectiveness of IR NDT depends on various thermal and optical properties of the material being tested. The thermal properties, including thermal conductivity, thermal diffusivity, specific heat and density are important and have been discussed extensively in many treatises on IR NDT. However the optical properties of the surface are equally important and while the thermal properties cannot be changed, sometimes the optical properties can be.Bare metal surfaces have high reflectivities and low emissivities, and as a result, they are generally not good candidates for IR NDT. Painted, coated, anodized, and oxidized metal surfaces can, in some cases, be successfully tested with IR NDT, but the effectiveness depends on the optical properties of the surface. It is well known by IR NDT practitioners that the easy solution to the testing of reflective materials is to paint the surface black. However, this is not always practical and it may not be permitted by the “owner” of the part.This paper demonstrates a process of analyzing the interaction of spectral curves that are relevant to the IR NDT process. This process can be used to evaluate the effectiveness of an IR NDT process for use on real parts with specific coatings and can help select a coating that may improve the effectiveness. This paper shows examples of optical properties for some typical paints and coatings that may be used on aluminum aircraft structures. It shows the spectrum of a generic incandescent radiant heat source and how the energy from this source is absorbed by several of these paints. Further, it shows the interaction between an IR camera detector response curve and the other curves. And finally, it shows how these three can be combined to produce an “IR NDT” efficiency rating for several examples.     

Applications of high resolution spectroscopy to the identification of far-infrared laser emission from optically pumped13CH3OH

High-resolution infrared (IR) and far infrared (FIR) Fourier transform absorption spectra have been employed to investigate assignments of FIR laser lines reported from optically-pumped¹³CH₃OH. The spectroscopic measurements are used in conjunction with the reported IR pump and FIR laser frequencies to form closed combination loops for several systems, serving to confirm the assignments and in some cases to improve the accuracy of the FIR laser frequencies. Frequency predictions from combination differences are also presented for a number of potential new FIR laser lines.