Engineers have built an ultra-powerful yet ultra-thin digital camera by folding the telephoto lens in a way reminiscent of origami paper folding.

The team at University of California, San Diego (UCSD) said that the technology could yield lightweight, ultra-thin, high-resolution cameras for a variety of uses including unmanned surveillance aircraft, mobile phones and infrared night vision.

"Our imager is about seven times more powerful than a conventional lens of the same depth," said Eric Tremblay, an electrical and computer engineering Ph.D. candidate at UCSD's Jacobs School of Engineering.

Tremblay is working with Joseph Ford, a professor of electrical and computer engineering at the Jacobs School, who leads the camera project within UCSD's Photonic Systems Integration Lab.

"This type of miniature camera is very promising for applications where you want high resolution images and a short exposure time. This describes what cellphone cameras want to be when they grow up," said Ford.

"Today's cellphone cameras are pretty good for wide angle shots but, because space constraints require short focal length lenses, they are terrible when you zoom in: blurry, dark and low contrast."

To reduce camera thickness but retain good light collection and high-resolution capabilities, Tremblay replaced the traditional lens with a " folded" optical system based on an extension of conventional astronomical telescopes that use mirrors.

"The folding idea was new in 1672, but they were doing it with two separate mirrors. We cut all our reflective surfaces out of a single component and quadrupled the number of folds," said Ford.

Instead of bending and focusing light as it passes through a series of separate mirrors and lenses, the new system bends and focuses light while it is reflected back and forth inside a single 5mm optical crystal. The light is focused as if it were moving.