Measuring freeform optical surfaces with NANOMEFOS

Demcon is a high-end technology supplier of products and systems, focusing on high-tech systems and medical devices. Demcon works closely with TNO and TU Delft, for example within Dutch Optics Centre (DOC). As a result of this collaboration, DUI (Dutch United Instruments) was founded. DUI's first product is NANOMEFOS, an advanced measuring instrument for freeform optical surfaces that was developed by TNO. “Ten years ago, TNO already believed that if you can make freeform optics, you should also be able to measure them. Through DUI we are now taking development and marketing further, starting in China. It is very valuable to pass on knowledge to SMEs in this way,” says Gerard van den Eijkel of Demcon.

Nanomefos

NANOMEFOS can measure large sections of optical elements accurately and quickly on a nanometre scale. Aspherical and freeform optics, increasingly used in high-end optical systems, are difficult to measure using conventional methods. NANOMEFOS is unique in being able to manage this. This fast, non-contact machine is suitable for measuring optics from flat to freeform and up to a diameter of 600 mm. The instrument acts as a large CD player, placing the surface to be tested on an air-bearing spindle while an optical probe is placed over it by a motion system. The prototype developed by TNO was further optimised, industrialised and made ready for production by Demcon, in collaboration with DOC.

 

China

In China in particular, parties are currently interested in NANOMEFOS. It is not entirely by chance that the abbreviation DUI means ‘correct’ in Chinese. An important market is space travel and large mirrors/telescopes on Earth, but in fact all industrial sectors that use (freeform) optics can benefit. There are now three different NANOMEFOS machines that are suitable for measuring small, medium and large surfaces (up to 300 mm, 600 mm and 1000 mm). “Companies are looking for the right device for the right job, which is why we are expanding our portfolio,” explains Van den Eijkel.

Collaboration

The collaboration between DOC and Demcon, including within DUI, is going well and the lines of communication are short. The creator of NANOMEFOS, Rens Henselmans formerly of TNO, has now joined DUI. “We get a lot of support from DOC. The new NANOMEFOS will also be installed there, so DOC has the latest equipment and we have a test site in the Netherlands. A win-win situation in which we can market knowledge together, working on the market and on new products in a transparent way,” says Van den Eijkel. Also, new products and possibilities, such as a 2.5 metre optics machine and a freeform test site, are currently being considered by the collaborating parties.