Development of a UAV-mounted Imaging FTIR for real-time monitoring of natural and anthropogenic hazards

自然灾害的特点是受影响的面积大，影响的规模和范围迅速变化，以及受影响地区的交通和通讯严重中断。在自然灾害发生期间和之后，必须立即准确评估灾害影响的范围和严重程度，以协助部署应急服务和执行有效的减灾战略。对人为危害的评估要求不同，因为设施的位置和空间范围是已知的，而且通常相对有限。因此，对监测的要求是，对往往高度复杂的基础设施进行长时间的高空间和时间分辨率监测，这些基础设施往往可以离地数十米。采集具有基本的二维和三维空间和时间分辨率以及检测灵敏度的采样数据集，以满足应急服务、监管机构和商业用户的要求，是一项重大的监测挑战，并构成了关键的市场需求。各种各样的研究人员，利益集团，商业和应急和监管机构需要检测，量化和区分从点源到景观尺度的空间尺度上的地表气体释放。查明碳氢化合物气体散逸性释放的来源和通量是若干应急和商业监测战略的一个关键组成部分。生物气几乎完全由甲烷组成，而热（天然）烃气由甲烷、丙烷、丁烷和乙烷的混合物组成。垃圾填埋场的气体排放是议会和环境署面临的常见环境问题，而管道的无组织排放对于从家庭供应到大型石化设施的许多商业组织来说是一个非常昂贵和不便的问题。目前应对这些挑战的方法主要是基于地面和手动的。虽然地面方法在当地非常有效，但观测覆盖面的局限性往往会导致对灾害的性质和程度缺乏了解，从而导致遏制和应对战略的效力降低，造成更严重和更持久的影响。基于遥感的方法已经使用了一系列传感器和平台，但是它们的业务效用受到严重限制，因为它们不能获得灾害监测所需的最重要的物理参数（表面温度，特别是气体种类的识别和量化）。迫切需要开发一种低成本、坚固、低质量，这是一种可以安装在无人机上的成像系统，能够检测和区分逃逸气体，并准确解析表面温度。目前可用的基于成像的气体监测仪器不能以足够的精度分辨烃类气体。成像傅里叶变换干涉仪（FTIR）具有检测和量化碳氢化合物排放的潜力，但是成像FTIR的当前设计具有非常高的功耗，非常重，并且对于在UAV上的操作部署来说过于昂贵。该项目的目的是开发和验证一种低成本、重量轻、紧凑的傅里叶变换红外（FTIR）成像光谱仪，该光谱仪可以安装在无人机上，具有足够的光谱分辨率和辐射灵敏度来检测和量化逃逸气体。提取光谱发射率和表面温度测量值的能力将使表面温度能够更准确地解析，发射光谱图像将使人类的存在和基础设施的识别更准确。

Natural hazards are characterised by the large area affected, rapidly changing scale and extent of the effects, and severe disruption to access and communication to the affected areas. During and after the onset of a natural disaster an accurate and immediate assessment of the extent and severity of the effects of the event is critical in order to assist the deployment of emergency services and to implement an effective mitigation strategy. The assessment requirement for anthropogenic hazards differs in that the location and spatial extent of the facility is known and is usually relatively restricted. The requirement for monitoring is therefore for high spatial and temporal resolution monitoring over extended periods over often highly complex infrastructure which can often be elevated 10s of metres off the ground. Acquisition of sampling datasets with the essential 2 and 3D spatial and temporal resolution and detection sensitivity to address the requirements of the emergency services, regulatory agencies and commercial users is a significant monitoring challenge and poses a critical market need. A diverse range of researchers, interest groups, commercial and emergency and regulatory organisations require the detection, quantification and differentiation of surface gas releases at spatial scales ranging from point source to landscape scale. Identification of the sources and fluxes of fugitive releases of hydrocarbon gas is a critical component of a number of emergency and commercial monitoring strategies. Biogenic gas is composed almost entirely of methane whereas thermogenic (natural) hydrocarbon gas is composed of a mixture of methane, propane, butane and ethane. Gas emissions from landfill sites are a common environmental issue faced by councils and the environment agency while fugitive emissions from pipelines are a very expensive and inconvenient problem for many commercial organisations ranging from domestic supply to large-scale petro-chemical facilities.Current methods to meet these challenges are still largely ground-based and manual. While ground-based methods are locally highly effective the limitation in the coverage of observations can often result in a poor understanding of the nature and extent of the hazard resulting in less effective containment and response strategies producing more severe and longer lasting effects. Remote-sensed based approaches have been implemented using a range of sensors and platforms however their operational utility has been severely limited as they cannot derive the most important physical parameters required for hazard monitoring (surface temperature and especially gas species identification and quantification) at the necessary ultra-high spatial resolution in real-time.There is an urgent need for the development of a low-cost, rugged, low mass, imaging system that can be mounted on a UAV that has the capability to detect and differentiate fugitive gas escapes and resolve surface temperature accurately. Currently available imaging based gas monitoring instruments are not capable of resolving the hydrocarbon gases with sufficient accuracy. Imaging Fourier Transform Interferometers (FTIRs) have the potential to detect and quantify hydrocarbon emissions but the current design of imaging FTIRs have a very high power consumption, are very heavy and are prohibitively expensive for operational deployment on a UAV. The aim of this project is to develop, and validate a low cost, lightweight, compact imaging Fourier Transform InfraRed (FTIR) spectrometer that can be operational mounted on a UAV that has sufficient spectral resolution and radiometric sensitivity to detect and quantify fugitive gas escapes. The ability to extract the spectral emissivity and surface temperature measurements will enable the surface temperature to be resolved much more accurately and emission spectra images will enable the presence of humans and identification of infrastructure more accurately .