A strategy for the use of light emitting diodes by autonomous underwater vehicles

Abstract

Light Emitting Diode (LED) technology has advanced dramatically in a few short years. An expensive and difficult to manufacture LED array containing nearly 100 individual LEDs and measuring at least 5 cm² can now be replaced by a single 5 Watt LED smaller than a quarter. As the light output for a given package size continues to increase, doubling every two years, it is possible to consider using these new LEDs to improve existing lighting systems and to explore non-traditional methods of underwater photographic illumination. So, can these high-output LEDs be used for underwater illumination, under what circumstances are they a good choice, and what is the optimal way to deploy them for a given set of conditions? In this thesis I attempt to answer these questions. In this thesis, I tested these 5W LEDs in a number of conditions and orientations in order to simulate the lighting conditions experienced by autonomous underwater vehicles (AUVs) illuminating and imaging targets on the ocean floor. These LEDs were characterized and compared to existing lighting systems and methods. Their suitability for use both as vehicle-carried illumination and off-the-vehicle lighting packages was examined.

(cont.) Finally, conclusions were drawn as to the effectiveness of the 5W LEDs for underwater illumination and a guideline for LED illumination is presented to help AUV researchers determine the optimal lighting package for use on their missions.