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THE GIST

Japanese researchers have created an automotive laser system to replace spark plugs.
Tiny ceramic lasers ignite the air and fuel mixture with concentrated optical energy.
The durable laser system has the potential to improve fuel efficiency and engine performance.

Laser Spark Plugs

A standard spark plug (left) and the micro-laser for multi-point ignition (right). Click to enlarge this image.
Takunori Taira

Everything else about an automobile is being retooled to be leaner and greener, so it was only a matter of time before spark plugs got a second look. While they might seem like an essential component for ignition, a group of Japanese researchers think their lasers can do a better job.

"If you want save gasoline, cut CO2 and [emissions] with more power, new ignition should be required," said Takunori Taira, an associate professor of laser research at the Institute for Molecular Science in Okazaki, Japan, whose team developed the new system.

Each composite laser is made from ceramic powders heated up to become transparent, and then embedded with metal ions. Separate segments of the material are bonded together to make a laser that's nearly a half an inch long.

Several fast pulses provide enough concentrated optical energy for one of tiny lasers to ignite an air-fuel mixture. Unlike spark plugs, the lasers don't have electrodes that erode over time, making them ideal for use in clean-fuel vehicles. Taira said that the laser also works faster than a spark plug, which should improve fuel efficiency.

Other existing large-pulse megawatt lasers are complicated, unstable, inefficient, and costly, Taira said. And, until recently, pulse lasers were too large for use in with automobile engines. The new ceramic laser system that Taira's team created can fit into an engine's cylinder head.

Until this study, it was impossible to produce the kind of power needed for laser ignition in such a compact body, Taira said. Several years ago, a group from the Japanese automotive technology company Denso Corporation visited his lab to discuss using his lasers for ignition. That collaboration paved the way for the new laser's development.

These ceramic microchip lasers are suitable for mass production, which will bring down the price, Taira added.

A spokesman for Denso Corporation said that they can't provide details yet about the laser systems' retail price or impact on fuel efficiency because they are still in the research and development stage. Taira's group is working on a three-beam laser that they hope will be even faster than their current one. They will be presenting their laser research next week at the Conference on Lasers and Electro Optics in Baltimore.

Greg Quarles is a physicist as well as president and C.O.O. of B.E. Meyers and Company, which manufactures opto-electronics, including solid-state lasers. He specializes in laser materials and devices.

"This technology could revolutionize increased efficiencies in combustion engines, producing a cleaner and more efficient ignition of the fuel," he said of the Japanese laser system. The main advantages he sees are increased efficiency, durability, and potentially reduced repair costs if the lasers can help engines last longer.

In terms of mass production potential, this laser system is more complex than current spark gap technologies, Quarles said. "The maturity of this technology on the production floor is the greatest disadvantage, but one that can be easily overcome."

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