Immersion lenses (lenses that are immersed in a liquid, such as oil or water) can focus light into a spot size smaller than that possible in free space. Such devices are difficult to make, however, and often need to be hand polished for optimal performance. Now, a team of researchers at Harvard University in the US and the University of Waterloo in Canada has succeeded in making the first planar immersion meta-lenses using monolithic lithography instead of these traditional polishing techniques. The new lenses are extremely compact and can be designed to work in any immersion medium. They can also focus light through any number of multilayers with different refractive indices, something that is almost impossible using conventional lenses……
http://nanotechweb.org/cws/article/tech/68496
