Our Aim This project aims to develop and design a new satellite mission. This new mission concept will be a spaceborne multispectral 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.

Ultrafast lasers, those producing TIME-DOMAIN periodic sequences of ~100 femtosecond-duration pulses, also exhibit remarkable properties in the FREQUENCY DOMAIN, in which as "frequency combs" they serve as "wavelength rulers", enabling precision measurements of wavelength for spectroscopic and metrology applications. Despite maturing fibre-comb technology and steady progress in integrated optical combs, there is still no universal paradigm for the robust, compact and modular frequency-comb sources that are urgently needed for integration in future systems like optical atomic clocks. Building on recent EPSRC-funded research, which led to exciting new concepts in diode-pumped Kerr-lens-modelocked laser designs and engineering, we propose to develop a versatile and robust laser-frequency-comb architecture with broad applicability to a variety of industrial and academic sectors. We focus on GHz-rate diode-pumped solid-state ultrafast lasers as a platform technology offering efficiency, small size, robustness, high average powers, short pulses, low phase noise and high modal powers directly from the laser -- a suite of parameters which makes these lasers attractive for diverse applications in navigation, communications, dimensional metrology, spectroscopy and defence. Our programme envisions a platform technology that extends our recent demonstration of diode-pumped three-element Kerr-lens-modelocked Ti:sapphire laser architectures (800 nm) to Er,Yb:glass (1560 nm) and Cr:ZnSe (2400 nm), with designs optimised by Kerr-nonlinearity modelling. The wavelength coverage of these lasers will be enhanced by using tapered-fibres to generate broadband supercontinua from nJ pulses. Power-scaling in semiconductor optical amplifiers -- a technology perfectly matched to GHz-pulse amplification -- will be explored as a route to ultra-compact, high-power GHz systems. By adapting the 3-element laser design to configure two lasers in one cavity, we will demonstrate a simple and powerful dual-comb embodiment for high-speed distance metrology and spectroscopy. Proven designs will be progressed to higher TRL by using our proprietary micro-optical bonding technique to realise high-stability, self-starting laser configurations, suitable for evaluation and integration in applications. The project is supported by 8 academic and industrial partners who have offered cash and in-kind contributions totalling >£3M, representing considerable co-funding alongside EPSRC's investment. Their letters of support evidence the significance of the proposed technology for their businesses and illustrate their commitment to our research and development programme. As well as creating new academic knowledge and significant new engineering capabilities, the application of the compact ultrafast laser technologies we propose to develop could deliver profound socioeconomic impacts. For example, integrating compact combs into industrial metrology systems could enable lower-waste digital precision manufacturing; replacing 1550-nm cw lasers with GHz-rate ultrafast lasers could improve the resilience of Tb/s eye-safe free-space communications in all weathers, connecting remote communities; compact mid-IR sources could facilitate low-cost, multi-species sensors for 'net-zero'; and integrable Ti:sapphire combs could power future GNSS systems for distributing standard time and position across the globe. Each of the above examples maps to an industrial or academic collaboration embodied in our proposed programme of research, thus providing a realistic pathway to each of the impacts described.

The astronomy community faces a critical problem in how to provide perpetual online calibration of new ultra-high-resolution spectrographs, which play a central role in answering today's "big questions" such as the discovery of extra-solar Earth-like planets, and the variation of "fundamental" constants. Since around 2007, the photonics community has been working with astronomers to provide a solution, in the form of an ultra-stable laser calibration source producing a "comb" of thousands of regularly spaced optical frequencies. Techniques pioneered by Nobel laureates Hall and Haensch showed how such a comb could be stabilised, allowing the constituent comb lines to be frozen in frequency to precisions approaching one part in 1,000,000,000,000,000,000 (actually a level rather more accurate than is needed in many astronomy contexts). HIRES and ESPRESSO are proposed high-resolution spectrographs at the E-ELT and VLT, respectively, whose underpinning science cases include the search for Earth-like exo-planets, primordial nucleosynthesis and the possible variation of fundamental constants. Both instruments demand exceptional radial velocity accuracy and stability, (up to 2 cm/s for HIRES), which can only be realized by embedding perpetual online calibration in the form of a broadband laser frequency comb. No laser frequency comb technology fully offering the necessary wavelength coverage and mode spacing has yet been demonstrated. Furthermore, the current techniques used to obtain the necessary wavelength coverage and mode spacings introduce artifacts which corrupt the calibration results when deployed on a spectrograph. Consequently research is needed to explore the feasibility of alternative laser frequency comb concepts which could meet the needs of the ESPRESSO and HIRES projects. Building on unique laser frequency comb expertise at HWU, and working with stakeholders in the HIRES and ESPRESSO instruments, this project will evaluate several new concepts for broadband laser frequency comb architectures based around optical parametric oscillators, and addressing the essential calibration-source criteria for stability, uniformity, accuracy and comb-line spacing. Engagement in the project by our principal industrial partner, Laser Quantum Ltd., will support the project with Ti:sapphire pump lasers of high repetition rate, and with vital technical know-how. A further exploitation route is provided via the new Heriot-Watt spin out company Chromacity Ltd., formed to commercialise Heriot-Watt's femtosecond OPO technology. Outcomes from the project will take the form of a technical assessment summarizing the suitability of the candidate comb architectures, and a demonstrator of the most promising system.

This proposal aims to transition today's highest precision laser technology -- optical frequency combs -- from the lab to the factory, establishing the technique of dual-comb distance metrology as an enabling technology for manufacturing the next generation of precision-engineered products, whose functionality relies on micro-/ nanoscale accuracy. Optical techniques form the basis of critical industrial distance metrology, but face compromises between accuracy, precision and dynamic range. Time-of-flight methods give mm accuracy over an extended range, while interferometric trackers achieve nm precision but with no absolute positional accuracy. By developing novel dual-comb metrology techniques, this project will bridge the gap between precision and extended-range accuracy, providing traceable nm precision, with almost unlimited extended-range operation. For manufacturing industry, comb metrology therefore addresses the important problem of how to verifiably fabricate macro-scale objects with nano-/micro-precision. Building on Heriot-Watt's frequency-comb expertise, we will develop Ti:sapphire and Er:fibre dual combs, with the aim of demonstrating nm-precision controlled-environment metrology using Ti:sapphire, and micron-precision free-space ranging using eye-safe Er:fibre. Besides their novel applications in precision metrology, by implementing new efficient and compact diode-pumping schemes our research will extend laser comb technology in a way that makes these systems suitable for deployment in a wide range of environments outside the research lab, for example as modules in a precision quantum navigation system. Our project integrates key academic and industrial partners who will contribute resources and expertise in lasers (Chromacity), precision micro-optics (Powerphotonic), industrial metrology and manufacturing (Renishaw), ultra-precision metrology (EPSRC Centre for Innovative Manufacturing in Ultra Precision and CDT in Ultra Precision) and applications in large optics for astronomy (STFC UK Astronomy Technology Centre). The commitment of our partners is evidenced by >£300K of support, including £145K of cash which will be used primarily to support two EPSRC EngD and PhD students recruited to the project. The project aligns closely with the EPSRC's Manufacturing the Future challenge theme and the ICT Photonics for Future Systems priority, as well as the EPSRC's training agenda, by engaging EngD and PhD researchers from the CDT in Applied Photonics and the CDT in Ultra Precision. More generally, the project will support the UK's high-precision manufacturing and metrology communities, with potential academic and industrial benefits. By the end of the project we expect to have demonstrated and evaluated dual-comb distance metrology in a variety of practical manufacturing contexts (machine calibration, in-process control, finished-product inspection), and to be in a position to translate the technology into our industrial and academic partners.

Lake systems play a fundamental role in storing and providing freshwater and food, in supporting recreation and in protecting species diversity. However, the stability of these ecosystem services can be undermined by the increased demands society makes upon these systems and changes in atmospheric composition and lake water balance that arise through a societal-mediated changing climate. To safeguard against such loss of functioning there is in place legally-binding national and European directives that set stringent targets for water quality and biodiversity. Meeting these targets requires a detailed understanding of lake processes that in turn requires measurements at an appropriate temporal scale. Traditional monitoring, of at best weekly-fortnightly intervals, is sufficient to record seasonal change but cannot resolve the processes driving many aspects of lake function. To resolve these processes we need to 'hear every note in the full symphony of lake functioning', with such resolution only viable through semi-continuous measurement of parameters that are key reflectors of lake functioning. We are fortunate that deployed in eleven lakes across the UK, of different size, altitude, latitude and nutrient status, are basic systems automated to make such measurements, Automatic Water Quality Monitoring Stations (AWQMS). However at present, most buoys are restricted to a meteorological station and temperature measurements. A few have other probes to measure water quality, but these are subject to biofouling which could compromise the data. At present, the data are mainly downloaded by telemetry to the host-site via a range of procedures. Thus we are not utilising advances in data-logger-, computer- and sensor-technology to measure automatically at high frequency and 'hear the full symphony'. We propose to change this by installing stable, state-of-the-art sensor technology, with mechanical devices to minimise biofouling. Further, we will maximise the value of generating this high frequency data by linking together the lakes in a sensor network to deliver quality-controlled data onto the internet for analysis by project partners, the wider scientific community and the general public. Such infrastructure investment needs to reflect the need for high quality measurement from science-driven agendas. We will demonstrate such a network supports these agendas through the following projects: DST1: Real-time forecasting of lake behaviour: We will incorporate the real-time data available from the sensor network into a forecast system for lake phytoplankton behaviour and, in particular, to provide warning for the onset of phytoplankton blooms. DST2: The effect of meteorology on the fate of carbon within lakes: We will track pool and flux variability of dissolved carbon dioxide over daily to seasonal time scales. By relating these measurements to meteorological and within-lake physico-chemical measurements within and between sites we are better equipped to define critical controls on the lake carbon cycle. DST3: The level of regional coherence in sub-seasonal timescales: Lakes can show a regionally coherent response e.g. strong links exist between air and surface water temperature; large-scale weather patterns such as the position of north wall of the Gulf Stream have also been shown to influence directly the regional coherence of lakes. Use of high resolution data to examine coherence in lake temperatures has just begun but as yet no-one has investigated coherence of biological, chemical or wider physical variables on these short time-scales, an approach which is viable through this network. In summary, this sensor network of AWQMSs, offering detail of observation through high resolution data generation and the new instrumentation will demonstrate not only the value of observing the environment remotely and in detail, but the benefit from integration systems to offer real advances in environmental science.