Fibre-Based Fast T-ray Tomography

该项目的目的是展示太赫兹断层扫描，在毫秒图像帧速率。我们建议设计，建造和调试一个快速的多通道太赫兹层析成像系统，没有移动部件，利用一种新的太赫兹源的基础上短脉冲光纤激光器驱动的高功率激光二极管。光纤激光器的输出将被组合以通过差频产生来产生THz发射。从拟议的源的太赫兹发射的字符允许使用廉价的热电探测器阵列。大量的THz测量通道将被实现为并行和可重新配置的数据采集和处理电子系统。THz层析成像的速度和设备的突破将通过以下方面的新解决方案实现：光纤激光器; THz光学系统（差频产生，光束调节，探测器几何结构）;信号采集和处理;图像重建方法。提出的技术也将开辟一条道路，快速台式太赫兹层析成像与应用在广泛的领域的科学和engineering.We提出了一个演示实验，将采用这种新型的太赫兹层析成像系统，以映射主要物种的浓度和温度场分布在高压flames。这些火焰对于通常的IR分析技术是不透明的，因为来自烟灰颗粒的散射，但是申请人已经表明对于THz辐射是透明的。此外，这些火焰中的许多物种在太赫兹区域表现出吸收共振。因此，太赫兹层析成像有望成为研究高压火焰的唯一方法。这对我们理解例如航空发动机中的燃烧过程具有重要意义，可以提高效率并减少温室气体的排放。我们将证明在存在烟尘的高压火焰的情况下至少有以下性能：图像帧采集周期<1 ms;空间分辨率（面积）为D2/64的主要物种的横截面分布图;水分子的温度分布图（T~ 1000 K）。该项目是由RCUK资助的THz基础技术工作的直接结果，并结合了断层扫描（曼彻斯特），THz技术（利兹）和新型激光源（南安普顿）的专业知识。目前正在运行的基础技术THz工作与该项目之间的协同作用将允许在现实条件下识别火焰中化学物质的光谱行为，并指示用于温度映射的光谱线的最佳选择。该项目是THz层析成像的关键一步，用于气体混合物系统和各种其他物体的成像，预计将对THz技术的未来实用性和可负担性产生重大影响。

The aim of this project is to demonstrate THz tomography, operating at millisecond image frame rates. We propose to design, build and characterise a fast multi-channel THz tomography system without moving parts, utilising a new THz source based on short-pulse fibre lasers driven by high-power laser-diodes. The output of the fibre lasers will be combined to produce THz emission by difference-frequency generation. The character of the THz emission from the proposed source allows inexpensive pyroelectric detector arrays to be used. A large number of THz measurement channels will be realised as a parallel and re-configurable data acquisition and processing electronic system. The breakthrough in speed and facility of THz tomography will be achieved via novel solutions in: fibre lasers; THz optical train (difference-frequency generation, beam conditioning, detector geometry); signal acquisition and processing; methods for image reconstruction. The proposed technology will also open the way to fast benchtop THz tomographs with applications in a wide area of science and engineering.We propose a demonstrator experiment which will employ this novel THz tomography system to map major species' concentrations and temperature field distributions in high-pressure flames. These flames are opaque to the usual IR analysis techniques because of scattering from the soot particles, but have been shown by the applicants to be transparent to THz radiation. In addition, many of the species in these flames exhibit absorption resonances in the THz region. THz tomography therefore promises to be the only way to study high pressure flames. This has important implications in our understanding of the combustion processes in, for example, aero engines with the possibility of improving efficiency and reducing emissions of greenhouse gases. We'll demonstrate at least the following performance in the case of high-pressure flames in the presence of soot: image frame acquisition period <1ms; maps of the cross-sectional distribution of major species with spatial resolution (in area) of D2/64; maps of distribution of temperature (T~1000K) of water molecules. This project is a direct consequence of the THz Basic Technology work funded by RCUK and combines established expertise in tomography (Manchester), THz technology (Leeds) and novel laser sources (Southampton). The synergy between the currently running Basic Technology THz work and this project will allow the identification of the spectral behaviour of the chemical species in the flame under realistic conditions and indicate the best choice of spectral lines for temperature mapping. The project is a crucial step towards THz tomography for imaging of gas mixture systems and a variety of other objects, with expected strong impact on the future utility and affordability of the THz technology.