Say ‘cheese’ for the holocam

A camera that can take 3-D pictures in the form of holograms could soon be making waves for a wide range of marine related professions.

Marine biologists, divers surveying damage to underwater pipelines and oil rig structures and marine archaeologists investigating shipwrecks could all benefit from this advance in photographic technology.

The development and operation of ‘Holocam’ was described by physicists from the University of Aberdeen and Brunel University at the Institute of Physics Applied Optics and Opto-Electronics Conference in Loughborough.

The camera – originally conceived as a way of carrying out precise measurements and analysis of damage to underwater pipelines and the supporting structures of oil rigs – has been designed to operate down to a depth of 100 meters and can take 45 holograms on photographic plates. Once the plates have been processed, the holograms can then be displayed in a laboratory.

Researchers claim that a high level of detail is recorded, and during replay each 3-D image hovers in space.

Holograms are created using a laser beam. In off-axis holograms, the beam is split into two, and while one half is reflected by a mirror straight onto a photographic plate, the other half falls onto the subject, which, in turn, reflects it onto the plate.

When the two beams meet on the plate, a pattern of light and dark is produced. This pattern represents not only how bright the light from different parts of the subject is — which is enough information to produce a standard photograph — but also the distance travelled by each part of this light.

Light from areas of the subject that are close to the photographic plate has less distance to travel to the plate than light reflected off areas further away, so recording these distances provides the depth information needed for a 3-D image. Once the photographic plate is developed, shining another laser beam onto it at a specific angle produces the hologram.

The camera will first be used for recording the numbers and positions of plankton in the oceans. The current method of measurement is crude and does not give environmental researchers an idea of the distribution of plankton.

The holocam may, by contrast, take 3-D snapshots of around 100 litres of ocean, which preserves the relative positions of the marine organisms for further study.

The camera will soon be leaving Aberdeen for the Southampton Oceanography Centre, where it is scheduled to start sea trials on September 26.