Feature

Future Image

A new three-dimensional imaging system built out of bits and pieces has gained international attention for the University of Canterbury.

By Cathryn Crane, NZSM

Machines that produce three-dimensional images have long been the stuff of science fiction. They could provide everything from totally lifelike television to better medical services. A team at Canterbury University has developed the basis of a working three-dimensional imaging system superior to current 3D production methods.

There are several ways of producing three-dimensional images, but each has its own disadvantages. The 3D movie craze of the 1950s relied on double images, with special glasses producing the solid effect. The glasses were clumsy and the flicker from the separate images tended to leave viewers with headaches. Holographic images, produced using lasers, provide another approach to 3D, but can be viewed only from certain angles and require relatively expensive equipment.

The Canterbury engineers have come up with a simple system that produces 3D images viewable from any angle, without the need for special equipment. Their system has attracted considerable interest from overseas, with the pioneering research likely to make Canterbury a leading site in the cathode ray tube 3D field.

Old Idea Realised

The Cathode Ray Sphere (CRS) has its antecedents in the 1920s, when the concept was first suggested. At that time, the technology to construct such a device was not available, particularly the sophisticated computerised control systems needed to keep a stable image.

"Over the last century, many ingenious ideas have been discarded because of the absence of powerful computer systems," says project leader Dr Barry Blundell. He is keen to re-examine a number of early ideas that may now be attainable with modern technology.

Blundell has had an interest in 3D systems for some time, and began the CRS work as a project for his post-graduate students. It is providing PhD material for Grant Crombie and Adam Schwarz, and has 6 other students working on it.

In the CRS system, two cathode ray tube electron guns fire electrons at a rectangular glass plate sitting in the centre of an evacuated glass sphere. The plate is covered on one side with a phosphorescent material that glows when the electrons hit it. Spin the plate fast enough, and time the arrival and placement of the electrons correctly, and it produces a solid three-dimensional image.

The initial prototype used a stainless steel chamber made out of an LPG tank. It had only three viewing ports. Once the principle was shown to work, the tank was replaced with a 28-centimetre glass sphere, providing all-round viewing angles.

At this stage, the images are still relatively simple, progressing from sinusoidal curves to computer-generated tubular images. As the team develops better control equipment, more complicated patterns will become possible. The team are working to interface a dedicated microprocessor with an HP-Apollo workstation to provide a control system that can work effectively at the high speeds required.

Shoestring Budget

It's easy to tell that the project has a low budget. The central glass sphere was blown by technicians in the Chemistry Department out of beakers and conical flasks. The system's oscilloscope is a valve-filled device of 1940s vintage. A scavenged medical X-ray source provided further parts, and you stand under a big piece of black polythene to view the 3D tracery.

For all that, it matches anything produced elsewhere in the world. Blundell and his student team in the Electrical and Electronic Engineering Department spent just $750 in building the first prototype. One of the major advantages of the system is that it can be built out of inexpensive, common components.

Blundell has fought hard to gain funding for the project to continue, approaching over 100 companies throughout the country. He was disappointed to find no local interest in the device.

"We got 20 replies, but none were interested in supporting research and development," Blundell says.

There are numerous commercial possibilities for the technology. Medical imaging would benefit greatly from such a development, whether as a learning tool or as a diagnostic device. Air traffic controllers could operate more effectively and safely with a 3D screen, and computer-aided design would also benefit. These sorts of applications are well understood and appreciated overseas.

Blundell has found the financial limitations frustrating, particularly as trying to gain support takes up a considerable amount of his time. He puts the project's current success down to support from Southpower and Electricorp, and to the enthusiasm of the people working with him.

"Grant is doing his PhD work with no financial support at all, but he's very keen on working on it," he says.

Blundell came to the university from Britain two years ago and has taken to the New Zealand tradition of making do with the apocryphal No 8 wire. He quotes Lord Rutherford: "We have no money, therefore we must think."