Periodic Reporting for period 3 - Bug-Flash (Coherent Back-Lasing from Atmospheric Insects)
Berichtszeitraum: 2023-02-01 bis 2024-07-31
In this project we explore physical phenomena which could drastically improve remote monitoring and classification of insects in their natural habitats. This is important because insects are cornerstones in the food chain in terrestrial ecology, without them our ecosystems would collapse. Some insects transfer deadly diseases, others can ruin crops or timber production. At the same time, insects also pollinate our crops, and without them our diet would be tremendously boring. Accurate, real-time in situ surveillance is needed to manage and protect insects, but also because their ecology is simply fascinating to learn about. There are many research groups and techniques aiming at insect surveillance; traps, genetics, machine vision, acoustics, radar and citizen science. Our work regards specular flashes from insect wings which can be retrieved by photonic devices. This coherent scattering can cause laser light to flip its direction and propagate backwards in a collimated fashion. This implies backscattering from insects does not necessarily attenuate by the squared range, this it gives a number of opportunities: We could detect very small insects, at further distances, using less laser power or sample at higher speeds.
In this project we explore the nature of specular flashes from insects and how information on nano- and microstructures in such flashes could provide the necessary specificity to distinguish the millions of insects species. We investigate museum species with polarimetric infrared hyperspectral imaging in specular mode and developing, build and test new lidar technology to capture light flashes from insects wings in field. This is far from trivial, flashes only last for a couple of microseconds and require sample rates up to hundred thousand hertz. During these random instances in time we want to capture enough light from a distant insect to deduce polarimetric- or spectral properties of the backscatter. After gathering hundreds of thousands insect lidar observations, we use statistics to infer the strange range dependence and the benefits in terms of species specificity.
In this project we explore the nature of specular flashes from insects and how information on nano- and microstructures in such flashes could provide the necessary specificity to distinguish the millions of insects species. We investigate museum species with polarimetric infrared hyperspectral imaging in specular mode and developing, build and test new lidar technology to capture light flashes from insects wings in field. This is far from trivial, flashes only last for a couple of microseconds and require sample rates up to hundred thousand hertz. During these random instances in time we want to capture enough light from a distant insect to deduce polarimetric- or spectral properties of the backscatter. After gathering hundreds of thousands insect lidar observations, we use statistics to infer the strange range dependence and the benefits in terms of species specificity.
Our group have conducted several large species surveys of pinned museum specimens. The species groups include bees, wasps, hoverflies, moths, butterflies, horseflies, table flies, dragonflies, mosquitoes, crane flies, grashoppers and beetles. For these surveys hundreds of speciment are remoistered and their wings are spreaded in a plane. Hereafter they are scanned with polarimetric hyperspectral imaging from 900-2500 nm. We have developed routines for manning out the nanometer thickness or surface roughness in every single pixel across the wings. Images also include quantitative information of secondary interest such as body melanisation and depolarization.
Our group have developed various pieces of instrumentation such as polarization lidars at different wavelengths, hyperspectral lidars and super fast lidars. We have also developed hyperspectral imaging methods and advances target characterization instruments. All of this specifically aims to answer questions on coherent scattering from insect wings. All of the instrumentation is also portable and deployable in field.
So far, our group have also made numerous field campaigns. Because of pandemic, these have primarily been in Sweden, but this have not prevented to adress our research questions and test feasibility of the methods we develop. We have conducted measurements on forestry pests, investigated biodiversitet assessment over a meadow and recorded polarimetric range profiles of mosquitoes over a lake. Some campaigns have only been aimed at testing technological concepts to evaluate signals to noise and field performance at different sample rates.
Some of the field campaigns yielded massive amount of data. It takes time to process such lidar and to interpret it properly. We spent time on developing robust lidar evaluation scripts and carefully inspect data. This is also the case for hyperspectral imaging of pinned insects.
Our group have developed various pieces of instrumentation such as polarization lidars at different wavelengths, hyperspectral lidars and super fast lidars. We have also developed hyperspectral imaging methods and advances target characterization instruments. All of this specifically aims to answer questions on coherent scattering from insect wings. All of the instrumentation is also portable and deployable in field.
So far, our group have also made numerous field campaigns. Because of pandemic, these have primarily been in Sweden, but this have not prevented to adress our research questions and test feasibility of the methods we develop. We have conducted measurements on forestry pests, investigated biodiversitet assessment over a meadow and recorded polarimetric range profiles of mosquitoes over a lake. Some campaigns have only been aimed at testing technological concepts to evaluate signals to noise and field performance at different sample rates.
Some of the field campaigns yielded massive amount of data. It takes time to process such lidar and to interpret it properly. We spent time on developing robust lidar evaluation scripts and carefully inspect data. This is also the case for hyperspectral imaging of pinned insects.
Our group only to push the state of the art in terms of physical understanding, biological knowledge and technological performance. We have developed spectral models for surface roughness of moth and butterflies, found links to micro-structure and encountered unexpected findings. We have proven that whole wings scatter fringed spectra and that these can be observed over distances, whereby the membrane thickness can be deduced with nanometer precision. We have shown that most related species in several orders differs significantly in wing thickness both between species and sexes. We have also developed lidar instrument with unpreceeded performance in terms of speed, resolution, sensitivity and spectral bands.