Towards Quantitative Optical Cross Sections in Entomological Laser Radar – Potential of Temporal and Spherical Parameterizations for Identifying Atmospheric Fauna

Brydegaard, Mikkel

doi:10.1371/journal.pone.0135231

Cited by 46 publications

(73 citation statements)

References 32 publications

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“…In comparison with the specular contribution, which is co‐polarized, the depolarized diffuse contribution only displays eight discernible overtones. Figure 9a,b illustrates laboratory high‐resolution recordings (Brydegaard, 2015) of a fruitfly, Drosophila melanogaster , with a fundamental frequency of 215 Hz. Figure 9c,d displays the modulation signature from a male Anax imperator .…”

Section: Results: Comparison Of Odonata Wips and Vision In Optical Domentioning

confidence: 99%

“…Our group has a previously remotely measured backscatter from airborne insects with kHz sample rates (Brydegaard, 2015; Brydegaard, Gebru, & Svanberg, 2014; Brydegaard, Merdasa, Gebru, Jayaweera, & Svanberg, 2016; Gebru, Brydegaard, Rohwer, & Neethling, 2016; Malmqvist, Jansson, Torok, & Brydegaard, 2016). To retrieve optical modulation spectra in the laboratory experiment, the light from a 808‐nm laser diode was collimated and transmitted 5 m across the room.…”

Section: Methods and Techniquesmentioning

confidence: 99%

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Can the narrow red bands of dragonflies be used to perceive wing interference patterns?

Brydegaard

Jansson

Schulz

et al. 2018

Ecology and Evolution

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Despite numerous studies of selection on position and number of spectral vision bands, explanations to the function of narrow spectral bands are lacking. We investigate dragonflies (Odonata), which have the narrowest spectral bands reported, in order to investigate what features these narrow spectral bands may be used to perceive. We address whether it is likely that narrow red bands can be used to identify conspecifics by the optical signature from wing interference patterns (WIPs). We investigate the optical signatures of Odonata wings using hyperspectral imaging, laser profiling, ellipsometry, polarimetric modulation spectroscopy, and laser radar experiments. Based on results, we estimate the prospects for Odonata perception of WIPs to identify conspecifics in the spectral, spatial, intensity, polarization, angular, and temporal domains. We find six lines of evidence consistent with an ability to perceive WIPs. First, the wing membrane thickness of the studied Odonata is 2.3 μm, coinciding with the maximal thickness perceivable by the reported bandwidth. Second, flat wings imply that WIPs persist from whole wings, which can be seen at a distance. Third, WIPs constitute a major brightness in the visual environment only second after the solar disk. Fourth, WIPs exhibit high degree of polarization and polarization vision coincides with frontal narrow red bands in Odonata. Fifth, the angular light incidence on the Odonata composite eye provides all prerequisites for direct assessment of the refractive index which is associated with age. Sixth, WIPs from conspecifics in flight make a significant contribution even to the fundamental wingbeat frequency within the flicker fusion bandwidth of Odonata vision. We conclude that it is likely that WIPs can be perceived by the narrow red bands found in some Odonata species and propose future behavioral and electrophysiological tests of this hypothesis.

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Section: Results: Comparison Of Odonata Wips and Vision In Optical Domentioning

confidence: 99%

Section: Methods and Techniquesmentioning

confidence: 99%

Can the narrow red bands of dragonflies be used to perceive wing interference patterns?

Brydegaard

Jansson

Schulz

et al. 2018

Ecology and Evolution

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“…The signal includes a low-frequency envelope from the insect body and an oscillatory component from the insect wings [30,31]. As observed in Fig.…”

Section: Numerical and Analytical Considerationsmentioning

confidence: 99%

“…The estimated range to observed insects is used to evaluate the scattering processes in and along the probe volume. In addition to evaluating the ranging capabilities of quadrant sensors, we investigate the validity of a previously proposed model suggesting a relationship between the flight heading of insects and the frequency contents of the received signal [30]. Finally, we test the method's capability of profiling vertical and horizontal insect fluxes.…”

Section: Introductionmentioning

confidence: 99%

Passive kHz lidar for the quantification of insect activity and dispersal

Jansson

Brydegaard

2018

Anim Biotelemetry

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Background: In recent years, our group has developed electro-optical remote sensing methods for the monitoring and classification of aerofauna. These methods include active lidar methods and passive, so-called dark-field methods that measure scattered sunlight. In comparison with satellite-and airborne remote sensing, our methods offer a spatiotemporal resolution several orders of magnitude higher, and unlike radar, they can be employed close to ground. Whereas passive methods are desirable due to lower power consumption and ease of use, they have until now lacked ranging capabilities. Results:In this work, we demonstrate how passive ranging of sparse insects transiting the probe volume can be achieved with quadrant sensors. Insects are simulated in a raytracing model of the probe volume, and a ranging equation is devised based on the simulations. The ranging equation is implemented and validated with field data, and system parameters that vary with range are investigated. A model for estimating insect flight headings with modulation spectroscopy is implemented and tested with inconclusive results. Insect fluxes are retrieved through time-lag correlation of quadrant detector segments, showing that insects flew more with than against the wind during the study period. Conclusions:The presented method demonstrates how ranging can be achieved with quadrant sensors, and how it can be implemented with or without active illumination. A number of insect flight parameters can be extracted from the data produced by the sensor and correlated with complementary information about weather and topography. The approach has the potential to become a widespread and simple tool for monitoring abundances and fluxes of pests and disease vectors in the atmosphere.

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“…Very recently, the Lund University group has also introduced a passive lidar technique, where range information can be obtained by using a split‐sector detector (Jansson & Brydegaard, ). A likewise low‐cost but very powerful active lidar concept using CW diode lasers was introduced by Brydegaard () and Brydegaard, Gebru, and Svanberg () using a short‐baseline, bi‐static lidar arrangement employing the so‐called Scheimpflug principle to attain infinite focal depth. Compared with the traditional entomological radar, lidar systems in the optical regime have the potential of achieving better sensitivity and specificity.…”

Section: Introductionmentioning

confidence: 99%

Application of lidar remote sensing of insects in agricultural entomology on the Chinese scene

Song

Zhang

Feng

et al. 2019

J Applied Entomology

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Insect pest management is a very important aspect for plant protection in crops production. Remote sensing provides a large number of techniques that are beneficial in entomological research. Although entomological radars have been used for studying migrations of insects for many years, most of entomological radar studies have been vertically tracing high‐altitude migration behaviour of insects. Light detection and ranging (lidar) is a counterpart to radar, now operating in the optical part of the electromagnetic spectrum, which has been recently applied for monitoring of insects at low altitude. Such techniques, in particular low‐cost continuous‐wave (CW) bi‐static systems based on the Scheimpflug arrangement, have been rapidly developing during the last decade. As a result, optical methods present new and fascinating possibilities. Based on experience from a 2‐week field campaign in rice paddy fields, we here present an overview of lidar remote sensing applied to the Chinese scene. The capability of a CW Scheimpflug lidar system in monitoring the insects was studied. We present results on insect abundance in relation to time of the day and weather conditions. We also identified insect species by analysing wing‐beat frequencies and studied their attraction to ultraviolet (UV) lamp located close to the horizontal laser sampling path during night time. Results showed that the insect species were abundant, that insects detected by the lidar system were attracted to light and that light rain increased the insect activity. The lidar detection system had a high read‐out frequency, enabling the estimation of insect wing‐beat frequencies.

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Towards Quantitative Optical Cross Sections in Entomological Laser Radar – Potential of Temporal and Spherical Parameterizations for Identifying Atmospheric Fauna

Cited by 46 publications

References 32 publications

Can the narrow red bands of dragonflies be used to perceive wing interference patterns?

Can the narrow red bands of dragonflies be used to perceive wing interference patterns?

Passive kHz lidar for the quantification of insect activity and dispersal

Application of lidar remote sensing of insects in agricultural entomology on the Chinese scene

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