Submersible Holography and its Application
Prof John Watson, Chair of Electrical and Optical Engineering, School of Engineering, University of Aberdeen, Scotland
The use of holography in biological science dates back to the mid-1960s. Several underwater holographic cameras were developed and deployed subsea to study plankton populations and their distribution in the water column. These early “holocameras” were based on “classical” holographic recording on photographic emulsions. For in-water deployment their weight and bulk precluded deployment on advanced observation platforms such as ROVs or AUVs, or in global observation networks, and limited operation to a few hundred metres depth. Advances in electronic imaging sensors and computer performance have brought digital holographic (DH) recording coupled with numerical reconstruction by computer to prominence; and has led to the development of a range of smaller, rugged holocameras. Advantages of DH include rapid capture and storage of images, holographic video recording of moving objects and freedom from complex dedicated reconstruction facilities. Its ability to record true 3D, full-field, high-resolution, distortion free in situ images from which particle identification, dimensions, distribution and dynamics can be extracted is hard to match. The state-of-the-art in underwater holography is reviewed, along with a description of some of the underwater holocameras which are now in operation, and their application.
Biography: Professor Watson holds the Chair of Electrical and Optical Engineering in the School of Engineering at the University of Aberdeen, Scotland. He has worked in applied optics for over 40 years with a particular emphasis on underwater applications. Of specific importance has been his work on subsea holography, initially for application in subsea inspection and later biological applications like imaging of marine plankton. His team have developed and deployed subsea “holocameras” in Scottish sea lochs and the North Sea. Other work has included subsea laser welding and cutting and laser induced breakdown spectroscopy. Prof. Watson is a Senior Member on IEEE and fellow of IET and IoP.