Eye-like lens would be better, cheaper
A flexible light-sensitive material that could revolutionize photography and other imaging technologies is being developed.
At the University of Wisconsin-Madison Electrical and Computer Engineering Associate Professor Zhenqiang Ma and colleagues have developed a breakthrough material that could, perhaps, change the way we take pictures.
The one thing that has not changed with cameras very much over the years is the lens. Yes, they are made of plastic but the order in which they are assembled is quite old. For example, many digital cameras use the Tessar lens which was invented in 1902.
Now comes a new technology that was featured on the cover of the January 5 issue of Applied Physics Letters.
This is a bit complex but hang in there.
When a device records an image, light passes through a lens and lands on a photodetector — a light-sensitive material like the sensor in a digital camera. However, a lens bends the light and curves the focusing plane.
In a digital camera, the point where the focusing plane meets the flat sensor will be in focus, but the image becomes more distorted the farther it is from that focus point.
Zhenqiang Ma said, ‘If I take a picture with a cell phone camera, for example, there is distortion. The closer the subject is to the lens, the more distortion there is.’
High-end digital cameras correct this problem by incorporating multiple panes of glass or plastic to refract light and flatten the focusing plane. And it works but not totally. Even high-quality lenses stretch the edges of an image somewhat.
Zhenqiang Ma’s curved photodetector could eliminate that distortion. In the eye, light enters though a single lens, but at the back of the eye, the image falls upon the curved, not flat, retina, eliminating distortion.
The thought is that if you can make a curved imaging plane you would just need one lens.
Ma and his group can already create curved photodetectors — extremely thin, flexible sheets of germanium, a very light-sensitive material often used in high-end imaging sensors. So far, the group has demonstrated photodetectors curved in one direction, but Ma hopes next to develop hemispherical sensors.
He said, ‘We can easily realize very high-density flexible and sensitive imaging arrays, because the photodetector material germanium itself is extremely bendable and extremely efficient in absorbing light.’
Sure. That is in the laboratory. Bringing it out into the commercial world is another thing.
But the ability to create a lens that will, because of its overall curvature, be totally distortion free is the Holy Grail of lens. It will happen one day. Whether this is the answer depends. But it shows how close we are getting.
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