Invited Speakers

John Watson received a PhD for his work on laser induced ablation spectroscopy from the University of St. Andrews, Scotland in 1978. He joined the UK Atomic Energy Authority at the Dounreay Fast Reactor site in 1976 where he worked on instrument development for nuclear plant inspection. Prof Watson returned to the academic life in 1981 when he joined Robert Gordon’s Inst of Technology in Aberdeen as a Lecturer in Electronic and Electrical Engineering before moving to The University of Aberdeen’s Dept of Engineering in 1984. He was appointed to Senior Lecturer, then Reader and to a Chair (Professorship) in Optical Engineering in 2004. His main research interests are in holography, subsea laser welding, laser induced spectral analysis and optical image processing. His research group at Aberdeen have developed two underwater holographic cameras for the measurement and analysis of marine organisms and particles.
Prof Watson is a Fellow of The Institution of Engineering and Technology, a Fellow of The Institute of Physics and a Senior Member of IEEE.

Abstract

Underwater Holography and its Application to Monitoring of Marine Organisms

Watson, John, School of Engineering, University of Aberdeen, Aberdeen AB24 3UE, Scotland

In recent years, holography has grasped considerable attention for its application to monitoring and measurement of marine organisms and particles. Initially, subsea holographic cameras utilised classical photographic-based holography to record in-line reference and (sometimes) off-axis reference holograms. Image resolutions approaching 2 mm are achievable, allowed particle identification, and the distribution of species to be determined. However, such cameras tended to be heavy, bulky and not easily manoeuvrable or manipulated from a ship. To overcome these difficulties, later holo-cameras have been based around electronic recording of the wavefield and numerical reconstruction of the holograms in a computer. While the high resolution obtainable with classical recording is only achievable over a very small field the advantage of near real-time recording and replay and the ability to retain the fourth dimension (viz. time) in the recording of holographic movies more than offsets this. The holo-cameras are much more compact and easy to operate.

In this paper, the state-of-the-art of subsea holography and its application will be reviewed and illustrated together with some examples of work undertaken at Aberdeen University.