Live 3D imaging quantum LiDAR

Sammanfattning: In this thesis, I demonstrate a single­photon Light Detection And Ranging, (LiDAR)system operating at 1550 nm capable of reconstructing 3D environments live withmm resolution at a rate of 400 points per second using eye­safe laser pulses. Thesystem was built using off­-the-­shelf optical components and analysis was performedusing open-­source software. I utilise a single superconducting nanowire single photondetector (SNSPD) with 19 ps time jitter and 85% detection efficiency to achieve a 4 psdepth resolution in live measurements. I also show that by performing slightly moretime costly post analysis of the data it is possible to increase the details and smoothnessof the images. Furthermore, I show that the same LiDAR system and much of the algorithms usedfor 3D LiDAR can be used to perform Optical Time Domain reflectrometry (OTDR)measurements. I demonstrate that the system can identify interfaces between differentrefractive mediums such as fibre to fibre or fibre to air couplings with a depth resolutionof 9 mm along a single line. Using these reflections, I also show that the systemcan identify flaws in optical fibres as well as measure certain characteristics suchas absorption coefficient due to Rayleigh scattering or thermal expansion. Lastly, Idemonstrate that the same OTDR principles used in fibres can be applied to free­s-paceoptical setups and that the system can identify specific optical elements as well asmeasure the quality of the alignment of an optical system.