| Abstract |
In recent years the technology of unmanned aerial vehicles (drones) has transformed
agricultural practices. Applications such as chemical pesticidesspraying are performed
remotely without the need for direct contact. This application can be of great benefit
to farmers, especially in inaccessible environments where spraying is difficult.
Furthermore drone spraying has, additional, distinctive advantages such as fast
operation and water/ pesticide volume reduction compared to traditional land
spraying methods.
However, various considerations currently limit widespan endorsement of the
technique. The most important being related to the droplet cloud that is created
during spraying and can extend for several meters, even beyond the boundaries of the
desired spraying area. Therefore it is important to estimate the area covered by the
cloud. Also the amount of particles varies depending on the distance from the spraying
point and hence particle quantity in relation to distance should be determined.
Having several advantages over conventional electrical sensors (remote operation,
electromagnetic immunity and high sensitivity), fiber optic sensors are proposed as
the candidate sensors. Optical fibers with Long Period Grating (LPG) of a long
interaction area (~ 90 mm) have the ability to detect changes in their external
environment and can constitute a reliable choice for the specific application.
In this thesis, the process of inscription of Long Period Gratings using of ultraviolet
radiation and the point-by-point technique is presented. In addition, their response
was successfully tested during laboratory spraying experiments and their calibration
was performed by correlating the initial transmission spectrum with the induced
spectral changes.
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Ανάπτυξη αισθητήρα οπτικών ινών για παρακολούθηση εναέριων αγροτικών ψεκασμών
