Development of a Compact Modular Radiometer for Laboratory and Field Studies

红外滤光片辐射计用于精确测量穿过滤光片带通的辐射通量，滤光片置于热探测器前的光路中。本提案的目的是开发一种带有内置校准器的微型模块化辐射计，即紧凑型模块化辐射计（CMR）。微型滤光片辐射计相对普遍（例如，医院中使用的数字式耳温计），但很少有完整的、可追溯的校准目标。CMR将最近开发的用于微型空间仪器的技术（微型滤波器和高灵敏度非冷却宽带探测器）与目前正在开发的小型高精度校准目标相结合，以生产用于现场和实验室研究的通用微型辐射计。这笔拨款将用于制作一个功能齐全的仪器面包板，包括新开发的内置校准目标。与前几代仪器相比，CMR在两个关键领域提供了显著改进：它结合了强大的光学设计和集成的校准目标到一个高性能的微型仪器（900克）。以前校准过的辐射计（如月球占卜者，美国宇航局即将发射的月球勘测轨道器的一部分）的质量几乎是它的五倍。2. 与之前的紧凑型辐射计（如月球占卜仪）相比，包含中间焦点的红外滤光器显着提高了性能。通过选择不同的滤光带通，像CMR这样的辐射计由于其独特的分子指纹，可以对大气中的特定气体或地面上的不同矿物敏感。在经过适当校准的辐射计中，由于这些指纹而产生的辐射可以精确测量，如果使用多个过滤器（也称为“通道”），那么这些测量可以反向产生诸如大气温度或成分剖面，地表温度图和相对矿物丰度等数量。执行所有这些任务的仪器已经在牛津大学开发了40多年，用于飞机、船只、气象气球、地球观测卫星和其他行星的测量任务。CMR是一种高度灵活的仪器，适用于许多地面、空间和商业应用，例如：低数据速率，低功耗和机载校准使仪器非常适用于长期测量，如远程环境监测（例如对流层污染，火山二氧化硫水平测量等）。仪器的高灵敏度允许长路径长度测量，无论是主动还是被动，增加对痕量气体的灵敏度。2. 使用扫描镜与探测器阵列相结合，使仪器可以作为中等空间分辨率的成像辐射计。该仪器质量低，是使用无人机、大气研究气球和微型卫星进行实验的理想有效载荷。例如，利用对叶绿素光谱吸收特征敏感的滤光器遥感森林健康状况，从微型卫星或同一仪器的船载版本获取海面温度。原型仪器将用于测试其中的两种，作为概念的证明：首先，它将用于在实验室中测量水蒸气和气溶胶的低压混合物，以模拟从微型卫星上观察地球大气层。其次，它将用于测量接近地面的大气中不同高度的温度，以3D方式显示大气中的热量在一天中的变化情况。

Infrared filter radiometers are used to measure accurately radiant flux across the band-pass of a filter placed in the optical path before a thermal detector. The aim of this proposal is to develop a miniature, modular radiometer with a built-in calibrator, the Compact Modular Radiometer (CMR). Miniature filter radiometers are relatively commonplace (for example, the digital ear thermometers used in hospitals) but rarely have integral, traceable calibration targets. The CMR combines technologies recently developed for miniature space instruments (miniature filters and high sensitivity un-cooled broadband detectors) with small high accuracy calibration targets, currently under development, to produce a general-purpose miniature radiometer for field and laboratory studies. This grant will be used to produce a fully functioning breadboard of the instrument, including the newly developed built-in calibration targets. The CMR offers significant improvements over previous generations of instruments in two key areas: 1. It combines robust optical design and integral calibration targets into a high performance miniature instrument (900g). Previous calibrated radiometers (e.g. Lunar Diviner, part of NASA's upcoming Lunar Reconnaissance Orbiter) have masses nearly five times as great. 2. The inclusion of an intermediate focus dramatically improves the performance of the infrared filters when compared with previous compact radiometers such as the Lunar Diviner instrument. By choosing different filter band-passes, radiometers such as the CMR can be made sensitive to specific gases in the atmosphere or different minerals on the ground due to their unique molecular fingerprints. In a properly calibrated radiometer the radiance due to these fingerprints can be accurately measured, and if multiple filters (also known as 'channels') are used then these measurements can be inverted to produce quantities such as atmospheric temperature or constituent profiles, surface temperature maps and relative mineral abundances. Instruments that perform all these tasks have been developed at Oxford for over forty years and used to make measurements from aircraft, boats, weather balloons, Earth observing satellites and missions to other planets. The CMR is a highly flexible instrument suitable for numerous terrestrial, space and commercial applications, for example: 1. The low data rate, low power consumption and onboard calibration make the instrument highly applicable for long term measurements such as remote environmental monitoring (e.g. tropospheric pollution, sulphur dioxide level measurements at volcanoes etc). The high sensitivity of the instrument allows long path length measurements, either actively or passively, increasing sensitivity to trace gases. 2. Using the scanning mirror combined with the detector array allows the instrument to act as a moderate spatial resolution imaging radiometer. With its low mass the instrument is an ideal payload for use in experiments using unmanned aerial vehicles (UAVs), atmospheric research balloons and micro-satellites. E.g. remote sensing of forest health by using filters sensitive to absorption features in the chlorophyll spectrum, sea surface temperature from a micro-satellite or ship-borne versions of the same instrument. The prototype instrument will be used to test two of these as a proof of concept: Firstly it will be used to measure low pressure mixtures of water vapour and aerosol in the lab to simulate observing the Earth's atmosphere from a micro satellite. Secondly, it will be used to measure the temperature at different heights in the atmosphere close to the ground, to show how heat in the atmosphere changes through the day in 3D.