Three-dimensional holograms pinpoint plankton

17 Jun 2002

A revolutionary camera that can take three-dimensional pictures in the form of holograms could soon be used by marine professionals. Marine biologists, divers surveying damage to subsea pipelines and oil-rig structures, and marine archaeologists investigating shipwrecks will all benefit from this new piece of apparatus.

The "Holocam" will be described by physicists from the Universities of Aberdeen and Brunel, of the UK, in sessions at the Institute of Physics, Applied Optics and Optoelectronics conference in Loughborough on 18 September.

The camera can operate at a depth of up to 100 m and can take 45 holograms on each trip. Once photographic plates have been processed, the holograms can be displayed in a laboratory.

The camera will first be used to record the numbers and position of plankton in the oceans. Plankton are a sensitive indicator of the environment because they are the staple diet for many fish species. Until now the only method of assessing the number of plankton was to scoop up a container of seawater and count them using a microscope. However, this destroys information on where the different kinds of plankton are in relation to one another. In contrast, the camera takes a three-dimensional snapshot of around 100 l of ocean water, preserving the relative positions of the organisms for further study.

The Holocam was originally conceived as a way of carrying out precise measurements and analysis of damage to underwater pipelines and the supporting structures of oil rigs. The researchers hope that it will prove useful to marine archaeologists. When removing finds from shipwrecks is not possible, for political reasons or because the wreck is a grave, or if objects are difficult to raise, the level of detail the holograms can record provides a viable alternative to salvage.

The camera will leave Aberdeen for the Southampton Oceanography Centre in the UK, where it is scheduled to start sea trials on 26 September.