Olympic Cauldron

On September 15, 2001, exactly a year since the start of the Sydney 2000 Olympic Games, Sydney's world famous Olympic Cauldron was re-kindled in it's new, permanent home at Sydney's Homebush Bay.

The Olympic Cauldron was re-lit at dusk to beating drums and resounding cheers in its new location in The Overflow Park on Olympic Boulevard. The stainless steel bowl is suspended on new stainless steel legs and will stand as a permanent reminder of the success of the Games.

The project was conceived and designed by Barry Webb, Iain Clark and Fiona McVicar of Barry Webb & Associates, with Show Technology’s Architectural Products Manager Jonathan Ciddor assisting with the configuration, control and integration. Beyond AV, as the installation contractor, were responsible for the co-ordination, preparation, installation and programming of the lighting system for the Electrical Contractor, Heyday Electrics and the builder, Thiess Pty Ltd.

The Cauldron sits upon a concrete slab at ground level and beneath it is a large chamber 5 metres deep, housing the lighting equipment, pumping and gas controls, and a large water tank. On the ceiling of the pit are twenty-two Clay Paky Goldenscan 3 arranged in two rings. The outer ring has sixteen fixtures whilst the inner ring has six. The Goldenscan 3 are positioned with their mirrors up near the ceiling of the chamber projecting light through 220 mm round glass portholes.

The Goldenscan 3 were chosen for the project because their mirror offered the ability to move the light beam into a precise position. Another critical factor in the choice was the fact that the Goldenscan 3 deploy a HMI 1200 watt lamp enabling the beams to project over ten metres to effectively illuminate the cauldron and support structure, and water flowing down from above. The beams remain static and usually white in colour, colour changing reserved for special occasions.

“Because the beam angle is quite wide and the porthole quite narrow in diameter it was very difficult to get the beams to line up properly,” explained Con Andrews, Managing Director of Beyond AV. “Consequently movement of the beam is virtually impossible.”

Through out the design phase Fiona McVicar spent considerable time ray tracing the beams from multiple locations to ensure they would get through the port holes and at the same time achieve an even light distribution across the whole of cauldron and water flow. Once the portholes were cast in the pit’s roof slab there was minimal opportunity to adjust the beams, so design accuracy was paramount. To accommodate the requirements Show Technology and Clay Paky provided a special wide angle lens combination to increase the beam angle from the standard 16° beam angle out to 23°. This enabled a more uniform coverage of the Cauldron.

The control system is centred on the Martin LightJockey PC based control system and, with the recent software upgrade to include real time scheduling, can operate stand alone to activate specific cues as specific times or integrate to accept triggers from a diverse range of sources. The whole Olympic precinct exterior lighting was controlled by a conventional Clipsal CBus control system, including the Overflow Park, so it was essential that a simple interface allow the pre-programmed Cauldron shows to run reliably, precisely and in co-ordination with the park lighting. The Martin AD-DA interface for Light Jockey allows multiple external triggers to activate whole cue sequences. This way C Bus provides a contact closure and initiates the show.

Con Andrews described the significant components of the system “With 22 luminaires operating in an industrial environment, 5 metres off the deck, and below ground, with high pressure water and gas piping running all over the pit, the DMX is via individual opto-isolated runs through LSC splitters. This way if there is a cabling fault it is very fast and easy to locate. Luminaire interruptions are also minimised using opto-isolation.

“We also had to co-ordinate the power up of the Goldenscan 3’s. Striking 22 off 1200w HMI lamps pulls a significant current that would have required excessive power engineering. Using DMX to drive standard mains electrical contactors the Goldenscan 3’s are turned on and off in a sequence and are ready for each show.”

“The photos show some odd looking Goldenscan 3’s. All have been fitted with galvanized drip covers to ensure any condensation from the port holes is deflected away from the luminaires. The body of the units have been flipped as well. This enables the whole bottom plate, as well as the end plate and PCBs to be removed for cleaning and servicing. So when you are standing 5 metres off the deck life is as easy and safe as possible. It also means that the critical focus is not altered during servicing and maintenance.”

Jonathan Ciddor confirmed that these were significant issues identified right back at the design stage and were easily solved by Show Technology and ClayPaky recommending Goldenscan 3 for the project. When these issues were combined with the proven track record of Goldenscan 1, 2 and 3 over the last 10 years, the number of units in the Australian marketplace and the support available, it was a clear choice.

“I believe that the success of the project is a tribute to the team of lighting designers and technologists as well as the Australian architect Alec Tzannes,” concluded Barry Webb.