Researchers have now developed the first ultra thin flat lens that can now replace bulky lenses of cameras, telescopes and microscopes that can function with the highest efficiency across the the visible light spectrum.

The curved lenses found in cameras and telescopes are usually stacked together to prevent distortions and to be able to resolve a crystal clear image, as this is the exact reason why telephoto lenses are so long and powerful microscopes are so large in size.

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In this new study, researchers from the Harvard School of Engineering and Applied Sciences revealed the first ever planar lens that can work efficiently within the visible light spectrum which means that it can span an entire range of colors from red to blue hues.

This lens works by resolving nanoscale features that are separated by more minute distances compared to the wavelength of light passing through. This is completed by using an ultrathin array of tiny waveguides that are called metasurface that possesses the ability to bend light that is passing through it.

According to Federico Capasso of Harvard University, this is such a revolutionary technology since it works with the visible spectrum, which means that it can potentially replace all lenses in all types of devices ranging from cameras, microscopes to cellphone displays.

Researchers say that for red, blue and green light to focus in a visible light spectrum, a type of material is needed that would not absorb or even scatter light. This material should also be able to restrict and confine light inside a highly refractive index which should also be existing and being applied already in numerous industries.

By using titanium dioxide, researchers were able to utilize this common material found in paint to sunscreen, in order to build the nanoscale array of smooth, high aspect ratio nanostructures that is the major component of the metalens.

According to Mohammadreza Khorasaninejad from the Capasso Lab of the Harvard School of Engineering and Applied Sciences, the team was aiming to design a single planar lens that possesses a high numerical aperture which means that it can focus light into a single spot which is smaller than the wavelength of light.
Khorasaninejad adds, the more tightly packed that beam of light can be, the focal spot becomes ultimately smaller that potentially enhances the image resolution.

This new array designed by the team can resolve a structure so small, it is smaller than any light wavelength, at about 400 nanometers. With these scales, this metalens can provide a highly optimized focus than any existing commercial lens.  

The team also plans to use this mealens for wearable optics, flexible contact lenses and powerful telescopes in space. This new study is published in the journal Science. 

Tagsglass optics, metalens, ultra thin flat lens, flat camera lens, flat lens, planar optics, metalenses