The UK Astronomy Technology Centre (UKATC) and the University of the West of Scotland (UWS) have developed a novel adaptive optic technology. The aim of the STFC funded research on which this PIPSS proposal is based is to provide technology which will be used in the mirror systems of the European Extremely Large Telescope. Our technology concerns the deformable mirrors which are used to correct distortions in the light coming into the telescope from space, which in a ground-based telescope is usually caused by the light travelling through the earth's atmosphere. The deformable mirrors can be bent into shape to correct for the atmospheric distortion in the light waves. The bending forces are supplied by actuators, such as the piezoelectric stack actuators discussed in this proposal. The new technology we have developed enables us to have accurate knowledge of the extension of each actuator from a sensor embedded in the actuator itself. It can remove uncertainties caused by hysteresis in the individual actuators, which means that the control voltage cannot move the actuators correctly to the desired position. The sensing technique will be combined with a manufacturing process which enables dense arrays of miniature actuators to produced cost-effectively. The project partners have protected the intellectual property in this technology with a joint patent. Discussions with industry indicated that this technology is likely to have applications outside astronomy in advanced laser systems which also have deformable mirrors built in, for example for shaping a laser beam or removing distortion. Incorporating the technology into these systems will improve the speed and accuracy with which the laser beam can be corrected. During this project we will develop the technology for these laser applications, in close collaboration with the industrial partner.

Our Aim This project aims to develop and design a new satellite mission. This new mission concept will be a spaceborne multi-spectral canopy lidar (called SpeCL, 'speckle') that can measure the vertical profile of a forest and simultaneously determine the spectral characteristics of that profile. Since lidars can provide highly detailed 3D information on the structure of forest they have great potential in reducing the uncertainties in the terrestrial carbon cycle and of supporting the accurate mapping of land cover. The primary scientific objective of the SpeCL mission would be to determine the global distribution of above ground biomass in the world's forests using an appropriate sampling strategy, and to reduce uncertainties in the calculations of carbon stocks and fluxes associated with the terrestrial biosphere. Why is this important? Greenhouse gases associated with forestry (deforestation and degradation) accounts for roughly 17% of global emissions, more than the entire global transport network. A recent report to the Prime Minister (the 2008 Eliasch Review on Financing Global Forests) predicts that without action, the global economic cost of climate change caused by deforestation alone could reach $1 trillion a year by 2100. Most emissions of carbon from land-use change are currently from the tropics as a result of deforestation, which releases the carbon stored in biomass and soils to the atmosphere (as CO2) as organic matter is burned or decays. The regular monitoring and assessment of land cover change is therefore essential to understand the extent and impact of natural and anthropogenic changes Furthermore, analysis of the global carbon cycle shows that the annual emissions of carbon are larger than the annual accumulations of carbon in the atmosphere and oceans, suggesting a terrestrial sink for carbon in addition to that attributable to changes in land use. Remarkably, this as yet unexplained residual sink seems to have increased over the last decades in proportion to total carbon emissions, implying that carbon feedbacks are offsetting each other. This balance is unlikely to persist. The SpeCL mission is an opportunity to constrain both the net emissions of carbon from land-use/land-use change, and the residual terrestrial sink. Any further delay in understanding the carbon budget may have serious long term consequences if we leave too little time to respond. How will we do it? Edinburgh has pioneered the development of the world's first Multi Spectral Canopy Lidar (patent number 0808340.4). Using seedcorn funding from CEOI, we built the first 4-wavelength lidar, demonstrated its use in the lab and modelled the seasonal response. An airborne MSCL (A-MSCL) instrument has been designed and proposed to NERC on July 1st. In anticipation of future mission opportunities (and the long lead time required), there exists an imminent need for determining the feasibility and technical readiness of a spaceborne MSCL. In the first instance we will create a concept for the high cost, but low risk option of a traditional small satellite configuration with a cost ceiling of £100M. We will then aim to develop this concept to an ultra-low cost (<£5M), rapid deployment (within 3 years) micro-satellite platform using off-the-shelf components and where appropriate, 'proved' technologies. To this end we will consider the highly novel, high risk, but very low cost option of using a modular CubeSat platform.

Visible light is only a very small part of the whole electromagnetic spectrum. The radio spectrum is also very familiar to most people, but less well known is the range of wavelengths in between. In this project we are particularly interested in a part of the spectrum that has come to be known as the terahertz band, so called because the frequency is around 1 THz. Light in the terahertz band can pass through materials that are opaque to visible light, but yet, the wavelength is still small enough to resolve features smaller than 1 mm. Because of this terahertz has attracted a great deal of interest for applications where we need to see through materials, but also take good sharp pictures. Applications include medical and security imaging, particularly because terahertz is non-ionising so can be safely used with humans.Unfortunately terahertz technology suffers from some significant difficulties that requires research to overcome. Bright terahertz sources are difficult to make, so considerable effort is needed to improve what we have at the moment. Terahertz is energetically similar to ambient radiated heat, so sensors have to be both sensitive and highly descriminating. In a complete terhertz imaging system all aspects of the technology and its components are important in determining the overall performance. This project is therefore dedicated to improving sensor performance.There are a number of attributes that we would like for a good sensor. It should be small, consume little power, be very sensitive, and ideally, if it it to be used in an camera, fast enough to allow video rate imaging. We propose to use the optical properties of semiconducting materials and carefully designed metallic structures to capture terahertz radiation. We will demonstrate that these structures can be used to make an array of sensors, just as you would find in a normal camera, and that the sensors are sensitive and selective to terahertz. In the same way that mainstream photography has benefited from microelectronics to make digital cameras possible, we will also be able to make use of integrated circuit technology so that many sensors can be cheaply and efficiently put on to a single chip.Our project has attracted support from leading UK companies including Teraview and Selex-Galileo that have immediate routes to market for successful technology. Our aim is to complete the research that will demonstrate new technologies to the point where further investment will enable the creation of new products that can be used by scientists, clinicians and the security services in the not to distant future.

Large engineering structures such as railway and highway earthworks, bridges, pipelines and dams may need to be monitored for a number of reasons. These include general performance monitoring and providing a warning of incipient or actual failure (e.g. a landslip). New infrastructure construction projects, particularly large basements and tunnels in urban areas, may require extensive monitoring systems to enable the resulting ground displacements to be measured and compensated for where necessary. The cost of such monitoring, especially over large geographical areas which may be remote or inaccessible, is significant. More efficient monitoring and early warning systems have the potential to save large sums of money, and even human life. One of the most effective ways of assessing the performance of infrastructure is to measure surface variation (displacement) and relate instability or loss of performance to the rate of change of this variation. A number of technologies are currently used for surface variation measurement; these include extensometers, D-GPS systems, prism monitoring, reflectorless laser systems, photogrammetry, and interferometric linear ground based synthetic aperture radar. All of these systems have advantages and limitations. Many are expensive, some only operate over limited distances, others require installations to monitor particular locations (such as reflectors), and some will not operate in the dark or in poor weather.The use of satellite imagery offers the potential for cost-effective measurement of surface variations. Spaceborne Interferometric Synthetic Aperture Radars (InSAR) make use of orbiting satellites to image a given area. Images from successive passes of the satellite can be used to calculate ground displacements. The primary drawback with spaceborne InSAR surface change detectors is that they were developed for global, rather than local, area monitoring purposes and have a long satellite revisit time. Another potential problem is that using only one or two satellites, an area of interest could be in an electromagnetic shadow (i.e., the satellite cannot illuminate the area due to an obstacle blocking the satellite signal). This can occur especially in urban areas or hilly terrain.Recent advances have enabled the development of a subclass of InSAR using ground surface mounted receivers, the Passive Interferometric Space-Surface Bistatic Synthetic Aperture Radar (PInSS-BSAR). The PInSS-BSAR topology has a stationary receiver fixed on the ground, with the imaging antennae pointed towards the area of interest. A satellite moving relative to the surface generates an electromagnetic ranging signal illuminating the observation area. The signal is reflected by the earth's surface, and received by the radar antennae. By using two antennae, one fixed above the other, it will be possible to calculate the change in displacement in the vertical direction. PInSS-BSAR is best utilised using non-cooperative transmitters, i.e. satellites being used for other purposes. Global Navigation Satellite Systems, such as GPS and Galileo provide large numbers of non-geostationary, simultaneously operating satellites above the horizon, which illuminate a particular region at different angles. At any time, the satellites should cover the entire surface of the planet without any points in electromagnetic shadow. The range of such as system is expected to be kilometres, and its ability to monitor continuously will provide effective early warning of excessive displacements.The proposed research seeks to develop a cost-effective monitoring system using PInSS-BSAR to measure surface variations, with specific application to linear infrastructure such as roads and railways, and their associated embankment and cutting slopes. The prototype device will be verified against existing conventional surface displacement instrumentation already installed to monitor two large failing infrastructure slopes.

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