Researchers at the Fraunhofer Institute for Mechanics of Materials (IWM) have developed a fabrication process that lowers the cost of infrared lenses for thermal cameras by 70 per cent. The dramatic reduction in production cost would make thermal cameras more attractive for integration into cars as a driver warning system, for instance.
‘We have developed a production process for lenses that enables us to lower the costs of these components by more than 70 per cent. Thus the price for the micro-bolometer could be reduced,’ said Dr Helen Müller, a scientist at IWM.
Normally, the lenses are made out of crystalline materials like germanium, zinc selenide or zinc sulphide. These materials are very expensive and can only be processed mechanically – it takes grinding, polishing or diamond turning to shape them correctly, which involves high processing costs.
‘Instead of crystalline materials, we use the amorphous chalcogenide glass. Its softening temperature – that is, the temperature at which it can be formed – is low. Therefore, we can form it using non-isothermic hot stamping,’ said Müller.
The chalcogenide glass is formed using a press and, in contrast to conventionally processed optics, doesn’t need to be refined further. The lenses manufactured in this way exhibit the same excellent optical imaging quality as those that are polished. The scientists now want to refine the process further towards cost-effective mass production.
Currently, thermal imagers cost around €2,000, which is still expensive meaning they are only being used in luxury-class vehicles. Other applications for micro-bolometers – and thus for cost-effective lenses – include safety monitoring in industry and healthcare.
