Engineers of the Massachusetts Institute of Technology (MIT) have created a novel “metalens” that can shift focus at multiple depths without straining or shifting. Contrary to conventional lenses, this one is not made of toughened glass, but of “level-changing” transparent material.
As explained in the newly published study in the journal Nature Communication, once the material is heated, it can rearrange its atomic structure and change the way it interacts with light. This allows the metalens to shift the focus without the need for large mechanical components.
The fracture was triggered by the material used in rewritten CDs
The level-changing material was developed by throwing commonly used material into rewritten CDs and DVDs, known as GST. The method that allows data stored in CDs to be written, erased and rewritten has been used here.
The internal structure of GST changes when heated, allowing it to switch between transparent and opaque states. The MIT researchers coated the surface of this material with “tiny patterned structures.” What is special about these stuctures is that they work together as a “metasurface” to restore or reflect light in modern ways according to the changing properties of the material.
This is the trick that allowed the researchers to find the focus of metalens without moving. When the material was kept at room temperature, the metasurface was able to direct light to create a sharp image of material at a distant distance. After the material was heated by laser pulses, the metasurface changed light to focus on something further away.
“Our product demonstrates that our ultrathin tunable lens, without moving components, can achieve unparalleled images of overlapping objects at different depths, competing with traditional, bulky optical systems,” he said. Tian Gu, a research scientist in the MIT materials research laboratory, in an MIT press release.
The design currently has images inside the infrared band. Thanks to its proximity, it may be used to develop miniature zoom lenses for future drones, cell phones, or night vision goggles.