With gold against steamed-up glasses
Researchers at ETH Zurich have developed a coating for eyeglasses that heats up lenses with sunlight. The invention is intended to prevent them from fogging up.
The wafer-thin, transparent coating made of gold converts sunlight into heat, according to ETH. This prevents humidity from condensing on the surface. The coating could be used on eyeglass lenses and car windows, among other things.
A special feature of the coating is that it selectively absorbs solar radiation, said ETH researcher Iwan Hächler, who played a key role in the development. "It lets the radiation in the visible range through, but absorbs a large part of the invisible infrared radiation and thus heats up." Unlike existing anti-fog sprays, this coating is also permanent, he says, so you only have to do it once.
Only a little gold needed
Now products with the new type of coating are to come onto the market. ETH Zurich has applied for a patent for the development. "The technical prerequisites are already there. We have used a coating method that is already being used in industry," said Hächler.
The gold needed for the coating should not make the product noticeably more expensive. The gold price for coating a pair of spectacle lenses is in the range of 20 centimes.