30 Jul 2004
Researchers in Australia use two-photon polymerization to create a miniature model of the Sydney Opera House.
A tiny model of the Sydney Opera House with features as small as 350 nm has been unveiled by researchers at Australia's Swinburne University of Technology. Measuring just 64 x 38 x 41 microns, the team fabricated the one of the world's best-known landmarks to show the potential of stereolithographic microfabrication. (Journal of Optical Materials to appear)
The model took three hours to fabricate and is around one million times smaller than the real 185 x 120 x 67 m opera house.
"The model was made to demonstrate that arbitrarily shaped 3D microstructures with sub-micron-size structural elements can be generated using two-photon photopolymerization," Martin Straub from Swinburne's Centre for Micro-Photonics told Optics.org.
Straub says that the main purpose of the team's research is creating photonic microdevices and all-optical circuits. For example, the group has used the technique to fabricate woodpile-type photonic crystals.
The team's opera house is made from a polysiloxane photopolymer with acrylate organic functional groups. Key to the research is a photoinitiator, which Straub and colleagues add to the polymer to promote cross-linking. "This is the best structure we have achieved after about six months of material development and optimization of the fabrication procedure," he said. "In the focal spot, two photons combine to start the crosslinking reaction that locally solidifies the material."
Based on a glass coverslip, the model was fabricated layer-by-layer from the base upwards. The team used a 5-W pumped femtosecond-pulsed Ti:Sapphire all-solid-state laser system combined with an optical parametric oscillator with an intracavity frequency doubler. The resulting wavelength was 600 nm with an average power of 0.3 mW in the focal spot. This was focussed into the polysiloxane using an oil immersion objective.
Jacqueline Hewett is technology editor on Optics.org and Opto & Laser Europe magazine.
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