A compact novel hyperspectral imager for more reliable and precise agriculture

Lead Research Organisation: Durham University
Department Name: Physics

Abstract

Projections suggest that, without further action, the availability of water for irrigation will become a serious limiting factor to agricultural production and quality, particularly for growing cereals and potatoes. Many of the most productive regions of Great Britain at present, such as Kent and the East Anglia fens, are also where projections of both soil aridity and water scarcity are severe [1]. The Climate Change Risk Assessment Evidence report clearly specifies the need for a more coordinated action to achieve the ambitious reductions in water demand and to find solutions for future agriculture.

This research proposal is to address this particular issue by developing a novel concept of hyperspectral imager to remotely map the moisture content in crops and soil. At a time where scarcity of fresh water stocks is becoming an issue worldwide, the research will lead to an instrument offering precise feedback on the crop's water requirement and potential savings to farmers or communities. The proposed research will develop the next generation of space or airborne instrumentation for advanced sustainable agriculture, with a focus on strengthening resilience to environmental crises.

In the last decades, technological progress made in the field of Earth Observation instrumentation has revolutionised agriculture. Nowadays, hyperspectral technologies provide both valuable and essential information to modern agriculture by removing cost uncertainties from agricultural assets and by helping to prepare for and mitigate the effects of natural disasters. hyperspectral imaging techniques offer an accurate spatial and spectral snapshot of cultivated areas, helping in particular to monitor:

- water-stress, disease, insect attack, invasive species mapping and overall plant health

- seed sustainability, with remote measurement of the germination efficiency

hyperspectral instrumentation uses the spectral information in the image to reveal particular details about biology, mineralogy and chemical content, therefore providing valuable feedback regarding agriculture, earth science and environment.

Two novel instrumentation concepts will be developed and put together in this research to offer a step change in the hyperspectral capability, at the service of UK advanced sustainable agriculture. The first concept, capitalises on the use of an Integral Field Spectrometer integrating a slicer mirror (array of small thin slices of mirror) in a hyperspectral imager, and the second concept uses novel optical elements: Freeform gratings. Freeform surfaces are novel and revolutionary optical elements with no particular axis of rotation or symmetry. Traditionally, gratings are machined as flat or as lightly curved spherical surfaces because of limitations in the machining capability. Progress made in the field of ultra-precision machining can potentially enable the machining of complex, curved gratings to further improve the instrument compactness, image quality or modularity. Freeform optics are therefore promising components for space-based hyperspectral imagers for their ability to reduce the overall dimension, and therefore mass, of the satellite's payload, which is a critical parameter in space imaging systems.

[1] Committee on Climate Change, "Climate Change Risk Assessment evidence report - Synthesis report: priorities for the next five years." 2017.

Planned Impact

The research proposal "A compact novel hyperspectral imager for more reliable and precise agriculture" is a multi-disciplinary project, which will endeavour to produce a reliable instrument using a novel optical element to meet agricultural requirements to maximise the academic, societal and economic impacts.

Freeform gratings are novel components and have great potential for commercial exploitation, maximizing both the economic and societal impact. This novel type of optical element will open up a wide range of applications in spectroscopy across diversion fields such as :

- Space: Freeform gratings are promising components for airborne or space-based hyperspectral imagers due to their ability to reduce the overall dimension, and therefore mass, of the satellite's payload, which is a critical parameter in space imaging systems.

- Bio-photonics and medicine: The substrate of the metallic freeform gratings can be machined into all sorts of shapes, making these components easy to miniaturize and incorporate into intricate optical systems.

- Food industry: Spectroscopy is an important tool in the food industry, providing quantitative and qualitative feedback on the food quality. Freeform gratings will have a key role to play in the next generation of spectrometers to analyse the chemical composition of food and drink.
As air- and space-borne hyperspectral imagery becomes cost-effective for precision farming and soil reclamation applications, better accuracy in assessing soil characteristics is needed for nutrients and amendment prescriptions, and irrigation management practices. This research offers the potential to map, from a remote platform the moisture level in soil and crops. At a time where scarcity of fresh water stocks is becoming an issue worldwide, the research will lead to an instrument offering precise feedback on the crops water requirements and potential savings to farmers or communities. Farmers will be the first beneficiaries ofthe technology developed in this research. The instrument will also provide feedback on crops monitoring such as measurement of disease, insect attacks, invasive species mapping and overall plant health.
The technology developed for this instrument can also find applications in space-based global measurement of greenhouse gases, such as atmospheric carbon dioxide (CO2), methane and helping keeping track of air pollution levels. Freeform grating could offer the accuracy, resolution, and coverage needed to characterize regional scale CO2 sources and sinks and quantify their variability over the seasonal cycle. Research work in this field will help the UK to keep a leading position in the design of space and remote sensing instrumentation.
The UK industry will also benefit from the research in this proposal with 2 potential commercialization outputs identified:

- The commercialization of the freeform gratings as a novel optical element and their integrations within high quality spectrometers (not necessarily hyperspectral imager).

- The commercialization of the digital data obtained from the airborne measurement and its distribution to the UK agricultural community.

The project will also measure a range of UK soil samples and help to quantity the moisture content from the spectrum. No such analysis specifically studying UK soils has so far been performed, and the proposed research will be highly relevant to a multitude of academic groups working on hyper spectral imaging.

Publications

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Title Novel algorithm for computing tool path to produce blazed freeform gratings on a 5 axis diamond machine 
Description We have developed an algorithm which computes the tool path to produce a freeform grating on a 5 axis diamond machine keeping at the same time, the full control of the bazed angle. This tool can be used to produce diffraction gratings on a curved surface, adding optical power on top of the diffractive function of the grating. The blazed angle maximizes the efficiency of the diffracted wave in a specific diffraction order and help to make spectrograph more compact and efficient. 
Type Of Material Improvements to research infrastructure 
Year Produced 2018 
Provided To Others? No  
Impact This research tool has enabled a collaboration with the industry (which is at an early stage at the moment) Horiba Scientific with a commercial impact for the industry. 
 
Description HORIBA Scientific 
Organisation Horiba
Department Horiba Scientific
Country United States 
Sector Private 
PI Contribution Durham University has developed novel tool path algorithm for the machining of metallic blazed freeform gratings. Horiba Scientific is looking for a commercial partner to be able to produce these particular gratings and has offered free of charges assessment of the quality of Durham's components using their highy specialised equipment. If the quality is satisfactory, Durham University and Horiba Scientific will establish a commercial partnership building upon Durham University's technology for the production of masters and Horiba Scientific for the replication and high volume production.
Collaborator Contribution Horiba Scientific provides free metrology with highly specialized equipment.
Impact Horiba Scientific has performed some free metrology on some of the freeform gratings prototypes that we have sent to them. The optimisation process is on going and this partnership which help to improve the quality of the optical componnents that are being developed in this project.
Start Year 2019
 
Description Partnership with Blue Green Vision Ltd 
Organisation Blue Green Vision
Country United Kingdom 
Sector Private 
PI Contribution My research has lead to the development of novel freeform gratings which have a lot of potential in spectroscopy. The technology enabled more compact and high quality spectrograph. My research team has produce a prototype of a spectrograph to deliver on the research objectives. Blue Green Vision is interested in potentially using the prototype as a flagship in its next product range.
Collaborator Contribution Blue Green Vision is a new spin off company providing devices for high speed, non-contact, non-destructive identification of different types of plastics. This is a vital step in recycling and recovering the maximum possible value from waste plastics. We will offer solutions for difficult to identify black plastics and grades that are difficult to distinguish between using existing equipment. So far, Blue Green Vision has not yet made any contribution to the collaboration but is expected to come and assess the prototype performance with respect to its own requirement in the field of non-destructive identification of different types of plastics.
Impact The collaboration is just starting and some output will shortly come up.
Start Year 2020
 
Description Course material for Space Optics Instrument Design & Technology 2020 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I provided some course material for an ESA workshop Space Optics Instrument Design & Technology 2020, for the lecture on Metal Optics presented by Fraunhofer IOF's Group Leader on Ultraprecision Manufacturing & Freeform Optics. About 50 international participants attended the course. The project was described in the presentation.
Year(s) Of Engagement Activity 2020
URL http://soidt.org/course2020/
 
Description EPSRC blog 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact A blog is reporting monthly on the progress of the project and on the science objectives. It has been viewed by 360 persons so far. The blog has enabled the project to be advertised nationally and will be advertised in the next conferences.
Year(s) Of Engagement Activity 2019
URL https://wordpress.com/view/ukremotesensingtechnologycentre.wordpress.com
 
Description EPSRC innovation placement - Karen Westland (PG Research) - University of Dundee 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Postgraduate students
Results and Impact Through an EPSRC funded innovation placement, we have assisted a PhD student (Karen Westland) to make optical components as part of her PhD project at the University of Dundee. The visit has helped her to assess the technology to make high quality optical surfaces and have a successful PhD. It has also developped links between Durham and Dundee universities.
Year(s) Of Engagement Activity 2019
 
Description Invited presentation to the Adaptive Optics Workshop "From the Eyes to the Sky" the 25-28 March 2019 in Chiang Mai, Thailand. Talk " Freeform Optics : Manufacturing, metrology and applications" 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Invited presentation to the Adaptive Optics Workshop "From the Eyes to the Sky" the 25-28 March 2019 in Chiang Mai, Thailand. Talk " Freeform Optics : Manufacturing, metrology and applications"
Year(s) Of Engagement Activity 2019
URL https://www.dur.ac.uk/cfai/recenthighlights/
 
Description St Teresa Catholic School presentation 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact In the framework of the https://www.primaryengineer.com/, I have presented my research and activity at St Teresa Catholic Primary School on the 28/02/2020 in front of 90 pupils (Year 3, 4 and 5). I have also discussed with the pupil what is an optical engineer and what does this work involve.
There has been a lot of interest in each classes, and the pupils have asked a lot of questions such as : " What is the best UK education to become an optical engineer?", "How does optics work?", "What is my best invention?".
Year(s) Of Engagement Activity 2020
URL https://www.stteresasnewcastle.org.uk/wp-content/uploads/2020/03/AE84F9FF-07C1-4F5C-9C0A-7AFDF7F0131...
 
Description Telegraph article 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact I have presented my research activities and laboratory in The Telegraph article "From spotting space junk to diamond-powered satellites: Inside the North East's booming space industry" (07/07/2019). My research is having some impact in the space area, since the novel optical elements that are being developed in this project could be potentially used in the next generation of Earth observation satellites. The photo in this article is of me in the lab, aligning optics.
Year(s) Of Engagement Activity 2019
URL https://www.telegraph.co.uk/technology/2019/07/07/spotting-space-junk-diamond-powered-satellites-ins...