Engineers at Caltech (Pasadena, CA) have developed flat optical doublet lenses that can be easily mass-produced and integrated with image sensors, paving the way for cheaper and lighter cameras in electronic devices.1
The technology relies on stacking two metasurfaces. In this case, the metasurfaces are dotted with silicon cylinders 600 nm tall and with varying diameters in the hundreds of nanometers. Each metasurface has tens of millions of these posts. The resulting f/0.9 lens is corrected for monochromatic aberrations at 850 nm and has an efficiency of 70%.
Depending on their structure, metasurface singlets often have aberrations that include field curvature; as in traditional glass doublets, these aberrations can be compensated in a metasurface doublet design, especially when a monochromatic design is used.
The Caltech team plans to integrate these lenses into miniaturized cameras and microscopes, and extend their functionality and spectral bandwidth.
Source: https://www.caltech.edu/news/future-flat-lenses-53375
REFERENCE:
1. Amir Arbabi et al., Nature Communications (2106); doi: 10.1038/ncomms13682
