Rewriting holograms

University of Arizona optical scientists have developed three-dimensional holographic displays that can be erased and rewritten in a matter of minutes.

The holographic displays are the first updatable three-dimensional displays with memory ever to be developed, making them ideal for medical, industrial and military applications.

'This is a new type of device, nothing like the tiny hologram of a dove on your credit card,' said UA optical sciences Prof Nasser Peyghambarian. 'The hologram on your credit card is printed permanently. You cannot erase the image and replace it with an entirely new three-dimensional picture.'

The device basically consists of a special plastic film sandwiched between two pieces of glass, each coated with a transparent electrode. The images are 'written' into the light-sensitive plastic, called a photorefractive polymer, using laser beams and an externally applied electric field.

The US Air Force Office of Scientific Research, which has funded Peyghambarian's team to develop updatable holographic displays, has used holographic displays in the past. But those displays have been static. They did not allow erasing and updating of the images. The new holographic display can show a new image every few minutes.