Stand-off, SPAD-enhanced Ultra-Violet Raman Spectroscopy

对范围内物质的检测对许多工业生产和安全过程极其重要。拉曼是一种有效的光学技术，可以用来确定物质的性质，但由于拉曼散射效应的弱，迄今为止一直局限于接触/短程操作。在这项计划中，我们将开发和评估不同的独立拉曼光谱仪，以解决核工业、采矿、医疗保健和制药生产等领域的不同工业、医疗和安全问题。技术挑战和我们的创新现有的拉曼光谱仪的主要局限性是：1)微弱的拉曼信号很容易受到不需要的背景荧光的干扰(例如来自生物样品的强自体荧光)，以及2)采集速度很慢。拉曼信号是在样品被激发后瞬间产生的，而在发出荧光信号之前有一定的延迟。这种延迟的特征是荧光寿命通常从数百皮秒到几十纳秒不等。为了准确地测量拉曼信号，最好的检测策略是有一个快速的传感器，能够只捕获拉曼发射，而忽略在超短时间段内出现的背景荧光。由于传感器技术的最新进步，我们能够应用创新的单光子传感器(称为SPAD)和皮秒秒表来强有力地定位拉曼信号。该项目的主要目标是：(1)开发多通道皮秒秒表；(2)集成SPAD和皮秒秒表阵列；(3)为所开发的系统开发固件/软件；(4)进行基准实验和与传统拉曼光谱仪的比较研究；参与碰撞产生活动；(5)使用紫外线激发源来最大化拉曼散射的强度。我们将整合一个为在设想的最终用户方案中部署而改进的单一系统；这种努力将是一项非常及时、新颖和具有颠覆性的成就。我们对单光子探测器的使用也在英国量子技术议程中发挥了重要作用，并将导致这些设备及时和高度创新的早期工业应用。

The detection of substances at range is extremely important to a number of industrial production and safety processes. Raman is a potent optical technique by which the nature of a substance can be ascertained, but to date has been limited to contact / short-range stand of operation due to the weakness of the Raman scattering effect. In this programme, we will develop and evaluate different stand-off Raman spectrometers to solve different industrial, medical and safety issues in sectors such as the nuclear industry, mining, healthcare and pharma production. Technical Challenges & Our InnovationThe main limitations of available Raman spectrometers are:1) the weak Raman signals can be easily interfered by unwanted background fluorescence (for example the strong auto-fluorescence from biological samples), and 2) the acquisition is slow. Raman signals are instantaneously generated from samples after they are excited, whereas there is a certain delay before fluorescence signals are emitted. This delay is characterised by the fluorescence lifetime usually ranging from hundreds of picoseconds to tens of nanoseconds. To accurately measure Raman signals, the best detection strategy is to have a fast sensor capable of capturing only the Raman emission while ignoring the background fluorescence appearing in an ultra-short period of time later. Thanks to the recent advances in sensor technologies, we are able to apply innovative single-photon sensors (called SPADs) and picosecond stopwatches to pinpoint Raman signals robustly. The main objectives of this project are:(1) Developing multichannel picosecond stopwatches;(2) Integrating SPAD & picosecond stopwatch arrays; (3) Developing firmware/software for the developed system;(4) Conducting benchmark experiments & comparison studies with traditional Raman spectrometers; Engaing in impact generation activities;(5) Using UV excitation sources to maximise the intensity of the Raman scatter. We will integrate a single system refined for deployment in the envisaged end-user scenario; such an endeavour would represent a highly timely, novel and disruptive achievement. Our use of single-photon detectors also plays strongly into the UK Quantum Technologies agenda, and will result in a timely and highly innovative early industrial application of these devices.