Development of a kHz optical remote sensing system for in situ insect monitoring

Gebru, Alem Kindeya (2016-03)

Thesis (PhD)--Stellenbosch University, 2016

Thesis

ENGLISH ABSTRACT : In this work we have developed a kHz optical remote sensing system for in situ insect monitoring applications. This is an active and passive remote sensing system based on laser and sunlight. This system showed potential for monitoring pollinators in agricultural fields. It enables the implementation of improved vector control mechanisms and pest management. The passive remote sensing setup called dark field spectroscopy uses sunlight as an illumination source. Considering the passive remote sensing techniques, it is shown that one can determine flight direction, retrieve spectral information, and resolve wing-beat frequency (and harmonics) and iridescence features of fast insect events. With regards to active remotes sensing technique, a number important range resolved quantitative assessments of insects such as size, speed and wing-beat frequency can be performed. It is shown that the CW-LIDAR based on the Scheimpflug principle improves the range resolution beyond the diffraction limit. The reason for this is because of the fact that the sampling frequency is in the order of kHz and insects behave like blinking particles similar to super resolution microscopy called stochastic optical reconstruction microscopy (STORM) where molecules blinks between bright and dark states. Generally, this dissertation highlights the potential of applied optical remote sensing techniques to remotely identify insects and understand their impact onan ecosystem.

AFRIKAANSE OPSOMMING : In hierdie werk het ons ʼn kHz sisteem ontwikkel waarmee insekte oor ʼn afstand in situ gemonitor kan word. Die sisteem is beide aktief en passief, gebaseer op laser- en sonlig. Die sisteem het potensiaal getoon om bestuiwers in ʼn landbou omgewing te monitor. Dit stel in staat die implementering van verbeterde vektor beheer meganismes en pes bestuur. Die passiewe opstelling, genoem donker veld spektroskopie, gebruik sonlig as ligbron. Met die opstelling kan die bewegings rigting, spektrale inligting, die frekwensie (en hoër harmonieke) waarteen die vlerke beweeg en glans kenmerke bepaal word van vinnige insek gebeurtenisse. Deur gebruik te maak van die aktiewe opstelling kan ʼn aantal belangrike posisie afhanklike kwantitatiewe bepalings gemaak word soos insek grootte, spoed en vlerkfrekwensie. Dit word verder getoon dat CW-LIDAR, gebaseer op die Scheimpflug beginsel, die afstand resolusie verbeter verby die diffraksie limiet. Die rede hiervoor is die feit dat die meet frekwensie in die orde van ʼn kHz is, en insekte hulle soos flikkerende deeltjies gedra, soortgelyk aan wat waargeneem word in die super resolusie mikroskopie tegniek, genaamd “stochastic optical reconstruction microscopy” of te wel STORM, waar molekules flikker tussen helder en donker toestande. In die breë gesien, beklemtoon die proefskrif die potensiaal van toegepaste optiese afstand meet tegnieke om oor ʼn afstand insekte te identifiseer en hulle impak op ʼn ekosisteem te verstaan.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/98623
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