DORTMUND, GERMANY - They protect drivers from bright sunlight, let water and dirt pearl off the windscreen and protect safety glass and the displays of mobile phones and tablets: we are talking about functional surfaces that turn glass into flexible masters of almost everything.
At glasstec 2014, LIMO Lissotschenko Mikrooptik GmbH, the laser and beam shaping specialist from Dortmund, is showing a new short-time tempering technology to heat and thereby functionalize these wafer-thin coating layers - very gently, extremely fast and with the highest level of precision.
The task sounds impossible: within fractions of a second, thin layers need to be heated to over 1000 degrees Celsius in order to activate their functions (such as sun protection or thin film electronics). These surfaces are often thinner than human hair (in numbers: from 0.1 to more than 100 micrometres) and contain miniscule particles and molecules that need to have cooled off again only tenths of a second after they have reached their refinement temperature so that they keep their desired properties and structural sizes. In addition, there is the problem that glass is a carrier material that can be weakened or destroyed through improper warming and cooling (what experts refer to as tempering).
"Glass is a fragile material. Processing the surface is a great challenge that can only be solved through very selective and extremely fast heating and cooling ", says engineer and LIMO's Director of Thin-Film Activation, Dirk Hauschild. The solution is the so-called in-line high-temperature process that can heat large areas of extremely thin functional layers in milliseconds with greatest precision. This is done by the Activation Line 300, the most powerful L³ LIMO Line Laser® source (the numbers for the experts: more than 13 kW CW output power with a homogeneous line focus 300 mm long; an intensity of up to 40 kW/cm²; unique beam quality M² < 3 in the processing direction; high electro-optic energy efficiency of over 40%).
LIMO developed this system to serve as an innovative system supplement to conventional oven and lamp tempering. Developed especially for continuous operation, this laser has an intensive and homogeneous output that is ideally suited for reliable 24/7 industrial surface tempering. In addition: due to the low heat capacity, the layers cool off quickly. Patented LIMO beam shaping automatically desensitizes and stabilizes the parameters of the process, guaranteeing homogeneous, large-area processing.
"Thanks to the line beam profile, the user is able to evenly temper large surfaces without changing the characteristics of the substrate material", explains Hauschild. "The Activation Line 300 makes it possible to have custom-made processes with 100% closed surfaces." Unlike the standard point-laser processing, this system also allows for very small energy and process areas that were not addressable until now. This innovative technology has the versatility that allows for use in short-term tempering (modifying surfaces and coatings through extremely fast heating and cooling), rapid thermal annealing (repairing crystals and activate dopants within milliseconds) as well as selective tempering (targeted heating of absorbing coatings). Mr. Hauschild has a standing invitation to interested parties from the glass industry: "Visit us at glasstec which takes place in Düsseldorf at the end of October 2014 and let us get together to talk about your challenges and how our Activation Line 300 laser source can help to solve them."
Get more information at the LIMO booth at glasstec 2014, Düsseldorf (21 - 24 Oct. 2014) in Hall 11, booth number 11A07 and at our presentation "Towards Novel Products, Performance and Cost Improvements by Means of Laser Treatment of Glass" on 20 Oct. 2014 at 5:40 pm at the convention "solar meets glass" (Exhibition Grounds Düsseldorf, CCD Ost).
