02 Mar 2009
Parallel processing scales up laser power for high-throughput machine tools.
Mobius Photonics, US, has developed a laser architecture intended to allow the average power to be scaled up to suit particular machining applications without sacrificing reliability. The principle involves the use of a master oscillator seeding multiple parallel amplifiers.
"In some applications, high average-power lasers are split into multiple beams to do parallel processing, but we use a different approach," Laura Smoliar of Mobius told optics.org. "In our system, the splitting is done at low power, and then there is separate but synchronous amplification of the low power beams."
This method allows the technique to be readily scaled up and applied to large panel processing operations, wafer scribing, micro-welding or marking applications. It also simplifies the design of the system and helps to boost reliability, according to Smoliar.
"In an 80 W system, it’s preferable to use four heads of 20 W each, rather than take one 80 W laser and split it into four beams," she said. "Our approach means that the highest power density in downstream optical components is reduced by a factor of four, both in the laser and throughout the customer’s system."
The Mobius design exploits fibre splitter technology originally developed for the telecoms industry. "Conventional diode-pumped solid state lasers are incapable of the scalability of the fibre-based architecture we have developed," said Smoliar.
According to Mobius, its fibre-based commercial system can produce 10 W in the UV, 18 W in green, and 30 W in the infrared, and offers independent control of the pulse repetition frequency (>200 kHz) and the pulse width (down to 2 ns) without any effect on the laser output.
The parallel-processing method has clear scope for achieving higher powers than the 30 W system Mobius has now demonstrated. "Our technology can be scaled further, and we have not found the upper bound yet," commented Smoliar. "The 30W system was limited by pump power. Further scaling up will involve higher power pumps, but also attention to the details of making the system reliable at those higher power levels."