Reference algorithms and metrology on aspherical and freeform lenses

Aspheres and freeform surfaces are components used in a variety of optical systems, from medical imaging to astronomy. They deliver better image quality compared to traditional spherical elements and as a result their use is growing rapidly. However, the ability to develop higher-performance aspheres and freeform surfaces is limited by the precision with which the shape of their surface can be measured. Although modern optical polishing techniques can remove material at the nanometre level, measurement techniques are unable to measure with the same degree of precision. This project has built on the work of the previous EMRP project IND10 Form, which achieved measurements below 100 nanometres, by developing new measurement capabilities within European National Measurement Institutes to routinely measure below 30 nanometres. The capabilities developed will strengthen Europe’s position in global optics, and will be used by industry to develop a new level in optical device performance.