An invention that puts us ahead of the world
April 2006
by John Dunn
Looking through the Guinness Book of Records you will see that Aberdeen University Engineering Department is credited with constructing and deploying the world’s most ambitious holographic plankton camera. Professor John Watson and his small team are also leading the world, with a pulsed laser digital holographic plankton camera.
I have spent most of my adult life at the Marine Laboratory Aberdeen sampling plankton in all its weird and wonderful forms, and have been privileged to have been part of a team which came up with some equally weird and wonderful pieces of machinery to try to catch some of the smallest and most delicate life forms in the sea. I felt that the holographic technology developed by John Watson’s team potentially offered a method of finding the density and composition of plankton without removing it from the ecosystem.
We are all familiar with simple holograms on credit cards, or on novelty greetings cards, but the holograms taken by the new camera are in a completely different league. To start with they require a significant amount of computing power to process the hard drive’s-worth of data produced by the camera, even on one dive.
Holograms allow us to see very minute particles in the water column and identify them because they are three-dimensional. No other technology is capable of doing this except the human eye.
Early in 2005 Professor Watson met with one of his commercial partners, CDL, and Fisheries Research Services at the Marine Lab, with a view to guiding the development of the new camera, the marine lab acting like a ghost customer. The laboratory’s unique plankton sampling platform – Auto Recording Instrumented Environmental Sampler (A.R.I.E.S.) – can take 110 samples at pre-programmed depths; at the same time it samples a wide range of other environmental parameters to depths of 3,500 metres. A.R.I.E.S. would allow the team to validate what the camera was photographing, as well as giving them other invaluable environmental data, and was big enough to take the camera and battery pack.
The laboratory could also offer the services of F.R.V. Scotia, one of the more stable fisheries research platforms, to deploy A.R.I.E.S with the camera system. During 2005 Dr Hongyue Sun of the Engineering department worked on the laser optics, experimenting and learning a little more about plankton, which I supplied from sampling carried out at Stonehaven from F.R.V. Temora.
Meanwhile Dr Gary Craig at CDL was wrestling with the design and manufacture of underwater housings, optical ports, and connectors. Elfortlight of Daventry were completing the construction of the unique pulsed laser, designed for its compactness and reliability.
We wanted to get the camera ready for a cruise on which I would be scientist in charge, sampling water and plankton in the Faeroe – Shetland channel and Northern North Sea. It is impossible to describe how stressful yet exciting it is to develop a new piece of equipment to go to sea. As the days disappeared and the sailing date of 10 December approached, things were not looking good.
As I busied myself with the logistics of the cruise, frantic phone calls and e-mails told their own story; due to a series of technical glitches we would have to sail without the camera and Drs Sun and Craig. We took on as much of the ancillary equipment as we could, promised to keep in touch, and hoped we could pick them and the camera up later in the voyage.
The sampling proceeded on Scotia in weather conditions which were marginal at best and occasionally downright atrocious, while Hongyue, Gary and their commercial partners dealt with the technical problems ashore. While we were working at the northern end of the Faeroe Islands, news reached the ship that one of the scientific crew had suffered a family bereavement. The weather was deteriorating quickly as we headed for Lerwick to drop off the crew member and pick up the camera and its two operators.
After a 17-hour journey on the Northlink ferry due to the bad weather, the camera and Drs Sun and Craig arrived on board Scotia, lying just off Lerwick. Despite their seasickness, they got on with setting up computers and preparing the camera for its first deployment.
The Scotia moved down into the North Sea due to severe weather in the North, and was carrying out a survey of an area where concentrations of copepods had been found in previous years. Copepods are one of the food items of some commercially-important fish. We found a suitable area and the camera was fitted to A.R.I.E.S. and deployed at night, never an ideal time to do anything for the first time at sea in poor weather, but it could not be helped. When the lead between the computer and camera was plugged in, we were hugely relieved to see that there was a significant amount of data there. Further dives followed and as Hongyue, battling against severe seasickness, processed the data, a shout of joy went up as the recognisable shape of a copepod showed on the computer screen.
It is impossible to display the full impact of the hologram of the copepod, because clever as modern computers are, they cannot yet convey three dimensions. Analysing the data collected so far will take some time and may yet yield even more amazing holographic pictures of plankton organisms.
In a matter of years we will have holographic three-dimensional televisions in our homes, the preserve of Star Wars until now. The impact of this first tentative step into the technology of the next century will be felt across the world of marine science, and should help us towards a greater understanding of the marine ecosystem and some of its smallest inhabitants.
The E holocam project was funded by the DTI under the Link/OSDA scheme.
JOHN DUNN has worked at the Marine Laboratory in Aberdeen since 1967. Married with two sons, he shares a keen interest in traction engines and fairground organs with his oldest son Christopher.
This is an article from the April 2006 edition of Leopard Magazine. To read much more like this every month, see our subscription details.