Scientists have developed an ultra-thin metal lens that can change the focus point of light depending on temperature without any moving elements.
Modern variable focal length lenses do their job well, but have complex structures made up of dozens of tiny mechanical and glass elements. Researchers at the Massachusetts Institute of Technology have proposed an alternative, consisting of just one lens and an infrared laser.
The team used optical material used in rewritable CDs as the basis for the creation of the metal lens. Under the action of a laser, it can switch between transparent and opaque states. However, MIT scientists have found that when selenium is included in the composition, it begins to respond to such effects in a different way..
When the temperature of the material changes, the atomic structure can reversibly pass from a disordered amorphous state to a crystalline state, changing its refractive power.
The team used a modified material to create an optical metalens with tiny structures etched into the surface to refract or reflect light in a specific way. Next, the researchers created a prototype lens by attaching the lens and aiming an infrared laser at it. Experiments have shown that as a new lens heats up, its focal length increases, but the sharpness of the image does not change..
According to the developers, in the future it will be possible to make a compact lens with built-in microheaters that can raise the temperature of the metal lens to the desired level in a split second. However, the question of cooling and returning to the initial focus remains open. In the future, the technology could be used to create tiny lenses for smartphones.
As a reminder, engineers have recently created the first flat type lens. «fish eye» 1 mm thick.
A lens invented that can change focus without moving parts
text: Ilya Bauer, photo: MIT