CrazyNeutrino said:
Researchers advance ultra-thin flat lens to capture perfect colors
Ultra-thin flat lenses suitable for photography are one step closer after a team of researchers at Harvard University made a major leap forward with its prototype wafer-thin flat lens. The new lens builds on the original prototype, which we first heard about in 2012, by using an achromatic metasurface to focus different wavelengths of light at the same point.
When the team from the Harvard School of Engineering and Applied Sciences (SEAS) initially revealed its ultra-thin, flat lens, it was able to focus light without distortions, despite being effectively two-dimensional at just 60 nanometers thick. However, light at different wavelengths responded very differently to its nanoantennas, meaning it could only work with a single wavelength of light at a time.
The new model uses a dielectric material rather than a metal for the nanoantennas. This is said to improve its efficiency and, combined with a new design approach, means it is able to produce a consistent effect by focusing multiple wavelengths of light at the same point to achieve instant color correction. This change allows the new lens to create a color image by focusing red, green, and blue at the same point.
The news article doesn’t say directly, and the images of lenses in that article are misleading, but this looks like one of the new metamaterials with a negative refractive index. If so, then this image shows how it really works.
