Lasers to light up industrial production | Science| In-depth reporting on science and technology | DW | 04.12.2013
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Lasers to light up industrial production

Lasers can cut, weld and melt a variety of materials. But, the beams of light of the future will likely look very different. They'll fire short flashes of light and do much more than today's conventional lasers.

Lasers have already revolutionized a number of industrial processes and the lasers of the future will continue changing the ways goods are produced and their ability to cut materials in an extremely precise manner will continue to lead to innovation in a number of fields.

The work of three German inventors who developed the ultra-short pulse laser for use within the industrial sector can be seen at Trumpf. The company in southern Germany near Stuttgart manufactures the industrial tool. The laser beam produced here can engrave the entire world map onto the surface of a pinhead and is so exact that even the tiny island of Sardinia can be seen clearly with the help of a microscopic lens.

Precise holes create efficient cars

Microscopic view of a world map drawn by a laser on the head of a needle Photo: Bosch

A laser drew the world on this 2 millimeter needle

German industrial giant Bosch uses the same technology to produce injectors for car engines, and is the only manufacturer worldwide to do so. Under one name or another, nearly every carmaker, whether in Europe, Asia or the United States, uses Bosch's injectors for the same purpose.

"It's about injecting fuel very specifically into the engine compartment," said Jens König, a developer and physicist working at Bosch. "This allows for a massive 20 percent reduction in fuel consumption. With that, car manufacturers build small and compact engines that still have a lot of power and low fuel consumption."

Fuel savings result from the precision holes that allow for the gas to be sprayed into the engine compartment under high pressure of close to 1,000 bar. The system is designed to burn the propellant cleanly and not allow it to hit the walls or top of the engine.

Mini-explosions instead of melted metal

In order to create such tiny and exact holes, the light from the laser is used in extremely short bursts. Stefan Nolte, a physics professor at the Friedrich-Schiller University in Jena, compared it to using a pocket flashlight.

"If I turn the light on for a second, it creates a beam of light that extends from the Earth to the moon," he told DW. "But in a few picoseconds, the light only extends one or two millimeters."

Two holes show that an ultra-short pulse laser is capable of making more precise holes Photo: Bosch

A conventional laser drilled hole on the left and an ultra-short laser drilled hole on the right

That means that the laser pulse only needs to last a few picoseconds - or billionths of a second - to do its job. When the light source reaches the metal discs, it momentarily reaches a temperature of around 6,000 degrees Celsius. That causes the metal to vaporize at the chosen spot.

"It means we're not really dealing with a laser beam anymore but a very thin slice of light," Nolte said, adding that the flash of light concentrates the laser's energy pulse. "That means we're dealing with an enormous amount of energy - several hundred megawatts and even up to a gigawatt - in the center of the light's pulse."

The pulsing process, repeated up to a million times per second, goes so quickly and the pulses are so short that the actual piece of metal does not heat up. This means the metal, or other material, does not melt or change shape while being cut or

Pulses occur in the semi-conductor

Special semi-conductors, called laser oscillators, are responsible for creating the high-energy pulses of light that allow the laser to work. The substance's molecular structure captures and concentrates the laser's light for a brief moment before releasing it.

Stefan Nolte, Dirk Sutter and Jens König standing in front of a ultra-short pulse laser Photo: Deutscher Zukunftspreis/ Ansgar Pudenz

Nolte, Sutter and König were nominated together for the German Future Prize

The extremely high pulse rate is created by using a specific wave length the semi-conductor is created for. "The interesting this is, the average power output from the laser is very low - about that of a light bulb. But, at its center the pulse is very high," said Dirk Sutter, a laser developer at Trumpf.

Unthinkable applications

But the process is good for more than creating fuel-efficient cars - nozzles for diesel engines and burners for oil heaters can also be made using the laser technology. Many smart phone manufacturers also use lasers to cut the glass used in their phones' screens.

Trumpf's lasers are being increasingly used the electronics industry. They can cut tiny circuit boards, enabling manufacturers to build smaller and smaller devices. The nominees for the German Future Prize said their lasers could also be used in medicine.

A stent cut by a ultra-short pulse laser Photo: Trumpf

Stents from polymers could deliver medicine inside of the body

Lasers are used to cut stents - tiny tubes that stop blood vessels from clogging. What's special about these stents is that they are made from a special polymer.

"Drugs are embedded within the polymer," team spokesperson Dirk King said. "After the stent is implanted within the body, the polymer gradually releases the medication, which helps with the healing process."

Without the ultra-short lasers it would be impossible to cut the polymer stents, the physicist added.

Ultra-short pulse lasers have been successful so far, but they have not yet found widespread use in many industries. That's likely to change soon, the researchers said, adding that such lasers could be capable to producing individual tools, parts and other goods of the highest quality in the exact quantities needed.

"We believe it is possible to replace many existing manufacturing processes," said Trumpf's Peter Leibinger.

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