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Flattening the Competition


Your future super-thin smart-phone with a holographic display function could have its roots in technology developed by Nanyang Technological University (NTU).
 
Professor Liu Ai Qun and his team have created a tunable flat lens that can manipulate light in different, controllable ways. Product designers can use it to make devices such as cameras and microscopes thinner than they are now, and even experiment with smart-phone holographic displays. 
 
Traditionally, lens-based devices use curved lenses that occupy more space. These bend light rays that pass through them to manipulate images, for example to make objects seem bigger or smaller. Each curved lens, however, cannot be changed after it is manufactured, so arrays of them are needed to work in tandem in, say, a camera for you to be able to zoom in and out before taking a picture. 
 
Flat lenses make use of two-dimensional metamolecules that can manipulate light rays, but these molecules also cannot be tuned once fabricated. Other scientists’ workarounds, which involved combining the molecules with elements that can be manipulated, inevitably spoiled the properties that allowed the material to control light. 
 
The EEE flat lens consists of an array of metallic rings that can be filled with liquid mercury, which has a low melting point and high electrical conductivity. Each ring is connected to pneumatic valves that can pump air into it and force mercury out, to change the mercury ring’s shape, say from a C to a U. 
 
Professor Liu Ai Qun from EEE said that their flat lens can manipulate light in different, controllable ways due to the individually adjustable mercury rings. He said: “The lens has much potential for applications such as high-performance devices in telecommunications. In future, it will also enable other applications such as 3D holographic displays for mobile phones.” 
 

The flat lens consist of a metallic ring array filled with liquid mercury
 


By Prof Liu Ai Qun School of EEE


 
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