Despite the fact that modern cameras, microscopes and other optical equipment have reached an unprecedented level of development in recent years, the optical technology that is used in all these devices and devices has not really changed much since its invention in the early 1700s. Even the most high-end equipment typically uses a lens technology developed around 1730.
The main function of lenses is to combine light waves of different lengths into a single beam, which would otherwise focus at different points in the future image. The use of lenses can solve the problem of chromatic aberration or purple halo, which occurs in the case of defocusing, because the light waves have different lengths. Although the lenses are quite effective, the various materials used in their manufacture make them not always convenient and expensive. In addition, their production requires very careful and precise polishing, as well as optical centering.
Scientists at Harvard’s School of engineering and applied Sciences (SEAS) have developed a solution. They created the “metacharacter”. It is a single-layer surface of nanopillars (in the image above) located less than one wavelength apart, which gives them the ability to manipulate phases, amplitude, and levels of light polarization, offering a simpler, cheaper, and more efficient way to correct chromatic aberration.
An additional advantage of the technology is that it can be used together with conventional optical components that refract light, which opens up opportunities for its application.
“Imagine that the light is divided into packets that move at different speeds and reach the desired point at different times. With the use of nonopillars, the packets will reach the focal point simultaneously, ” explains Wei ting Chen, a researcher at the SEAS laboratory of applied physics and the author of a published article describing the invention in the journal Nano Letters.
Developers metacharacter say that technology is “fundamentally different” from traditional adjustment methods, as is used here nanostructural engineering.
“Because of this, we can go beyond the material limitations of lenses and get a much higher performance,” adds co — author Alexander Zhu.
According to scientists, the technology can be used in all types of commercial optical systems, from the simplest lenses to the most advanced microscopes, where up to 14 high-end lenses can be used.
The developers also add that they are going to further improve the efficiency of the metacorrector, so that the technology can be used in compact optical devices and other advanced technology.