Speckles in Coherent LiDAR

Abstract: Speckles are a phenomenon which often appears in situations involving lasers. Their properties can be used as an advantage but in the case of LiDAR applications, they’re purelydestructive. The peaks and troughs of the intensity distribution across the collimatinglens can be seen as variations in signal strength at the detector. The project presented inthis paper examines the properties of these intensity patterns and how their various sizeseffects the sampled signal. This is done by experimental measurements with the use ofa coherent LiDAR accompanied by a simulation to recreate and explain the behavioursof the results obtained in the measurements. The study shows a simulation which exclusively takes speckle dependence into account successfully produce similar results asphysical experiments. The varying of subjective speckle sizes on the detector was foundto have little effect on the sampled signal quality, though the improved averaging of thesmaller speckles caused the signal strength to shift in tranquil manner.