What They Say
Optics.org reported that a project at the University of Rochester, in the US has developed a fabrication procedure for combining metasurfaces and freeform optics into one optical component, offering designers a route to simplifying the architectures of miniaturized optical systems. The work was published in Science Advances.
“There has not been any realization of a generalizable design-to-fabrication process for creating metasurfaces on a freeform substrate where both the metasurface phase response and the shape of the freeform optic are leveraged for imaging and aberration correction,”
the team said in its published paper.
Metasurfaces achieve their novel wavefront control through the presence of subwavelength structures manufactured on a substrate, influencing the reflection and refraction properties of that surface.
Freeform optical surfaces, technically defined as surfaces with no axis of rotational symmetry around a normal axis, are not limited to the classical descriptors of optical shape, and do not fall neatly into categories such as spheres, conics, or aspherics.
“Freeform optics has been around in some disguised forms, but modern advances in both fabrication processes and optical materials are making it possible to conceive and design freeform optical surfaces of much greater complexity,” commented Rochester’s Jannick Rolland to Optics.org in 2013, on the creation of the Centre for Freeform Optics (CeFO) by Rochester and UNC Charlotte.
“In the past, fabrication methods had to try and keep up with optical design. But now fabrication is ahead, and we are trying to catch up with the design mathematics and metrology. Just one weak link in the line from design to assembly will ensure that an optical product does not work, so we need all these different areas of expertise to work together.”
The new project from Rolland’s research group at CeFO represents a further evolution of this fabrication philosophy, allowing metasurface fabrication on a freeform substrate through the use of electron beam lithography (EBL) so that both can work in tandem. The team calls the resulting component a “metaform.”
What We Think
Interesting. Although there’s no ‘Moore’s Law’ for optics, there is a lot of working going on in this area that may really help the development of optics for augmented reality. Another case of ‘don’t bet against the engineers’! (BR)
