Division of Information and Communication Sciences

The Centre for Lasers and Applications has developed a solid state laser source operating in the yellow spectral region to coincide with absorption by haemoglobin for medical applications in dermatology and ophthalmology, and proves effective in the treatment of blood vessel disorders. A pre-production prototype has been developed and used in some clinical trials.

Prof Jim Piper, Dr Helen Pask

Click picture to enlarge

The Centre for Lasers and Applications (CLA) is at the forefront of research into the development of lasers to 'sniff' diseases on a person's breath. The laser-based technique that can be used for medical breath tests is called cavity ringdown spectroscopy (CRDS). This involves a laser tuned to a specific frequency bouncing rapidly back and forth inside an optical cavity formed by mirrors with very high reflectivity. This cavity also contains a sample of gas, for example, from a patient's breath. When the laser is shut off, the 'ringdown' or decay rate of the light leaking from the cavity provides information on the exact composition of the gas.

Orr and He have applied to patent an innovative cavity ringdown spectroscopy device which uses very small lasers developed for the telecommunications industry, and believe a prototype could be built at about the size of a small suitcase. The patent application for the CLA's CRDS laser-based system design has been facilitated by Macquarie Research Ltd, and potential partners are being sought to help with further development and with commercialisation.

News Articles:
Bouncing lasers off your breath yields amazing results
Sydney Morning Herald - 23rd October 2003 read article >>
Sniffing out disease
Macquarie University News - September 2003 read article >>

Florian Englich, Brian Orr & Yabai He seem pleased with a laboratory prototype of their new cavity ringdown (CRD) spectrometer

Florian English, Dr Yabai He, Prof Brian Orr, Richard White

Click picture to enlarge

Gallium nitride is conventionally grown at temperatures of over 950 degrees C on sapphire. At Macquarie University we've been growing gallium nitride by low temperature techniques, either by laser induced chemical vapor deposition, remote plasma enhanced chemical vapor deposition, or using a combination of the two (remote plasma enhanced - laser induced chemical vapour deposition). The growth temperatures used are below 650 degrees C, and the gallium nitride can be grown on other materials besides sapphire. Polycrystalline material is usually grown at these low temperatures, however we have discovered a technique of low temperature annealing that allows the material to be re-crystallised into better quality single crystal material.

Dr Scott Butcher, Trevor Tansley, Afifuddin

We have invented a pulse-excited excimer lamp that generates incoherent ultraviolet/vacuum ultraviolet (UV/VUV) light in pulses of short duration and high peak power compared to existing plasma lamp sources. The lamps are based on the dielectric barrier discharge (DBD) configuration facilitating long-lifetime operation of practical devices. Characterisation of laboratory-sized DBD lamps have demonstrated dramatic improvements in the peak-power of the UV/VUV output pulse, total UV/VUV output power, electrical to UV/VUV conversion efficiency, and spectral purity of the lamp, compared to conventional sinusoidal waveform excitation. Furthermore, the pulsed DBD plasma is characterised by a high degree of pulse-to-pulse stability and reproducibility, allowing effective optimisation of lamp performance to achieve specific UV/VUV output characteristics. The potential range of applications is very broad from materials processing and surface modification/cleaning/etching, time-resolved fluorescence in photochemistry, and water/air purification (Ozone generation).

Dr Robert Carman, Dr Richard Mildren, A/Prof Deb Kane

Click picture to enlarge

The Mathematics Department have developed a web-based system for producing quizzes which allow students to test their knowledge of mathematical ideas. Each quiz is different so that students may practice the quiz many times until they understand the questions and can get full marks. The variety of topics is large, including order of operations, factorisation, equation solving, manipulating fractions, indices and logs, inequalities, surds, absolute values, trigonometry, functions, counting problems, and many more.

Dr Ross Moore, Fran Griffin

In work funded by CSIRO through its support of Macquarie's Language Technology programme, researchers in the Centre for Language Technology have been developing unique software that automatically extracts and collates information from web sites. Built on XML and related technologies, the KELP system identifies nuggets of information within the text on web pages, and then combines this information to provide a valuable resource for users. The first domain of application of the KELP technology targets comparison of laptop computers: KELP operates like a dynamic consumer choice magazine, searching different vendors' web pages for relevant information and then providing a tabulated comparison of the different products. A first prototype of the system was completed in May 2002; in future work, the team intends to provide the same information via a sophisticated voice interface.

A/Prof Robert Dale, Dr Diego Mollá Aliod, Dr Rolf Schwitter