Scottish scientists create single-pixel camera for 3D images

A projector displays patterned light on the face on a mannequin. These patterns are used to produce a 2D image. A 3D image is then formed using a technique called "shape from shade"

Scientists in Glasgow have discovered a low-cost way to create 3D images.

Their system uses detectors which have a single pixel to sense light instead of the millions of pixels used in the imaging sensors of digital cameras.

The detectors can "see" frequencies beyond visible light, which researchers say could open up new uses for 3D imaging in medicine and geography.

They said the single-pixel detectors cost "a few pounds" compared to current systems, which cost "thousands".

It is hoped that the system's ability to senses wavelengths far beyond the capability of digital cameras and its low cost, could make it a valuable tool for a wide range of industries.

Researchers said possible uses could range from locating oil to helping doctors find tumours.

Miles Padgett

Crossword patterns
Prof Miles Padgett led the team at University of Glasgow's School of Physics and Astronomy, which developed the technique.

He said: "Single-pixel detectors in four different locations are used to detect light from a data projector, which illuminates objects with a rapidly-shifting sequence of black-and-white patterns similar to crossword puzzles.

"When more of the white squares of these patterns overlap with the object, the intensity of the light reflected back to the detectors is higher.

"A series of projected patterns and the reflected intensities are used in a computer algorithm to produce a 2D image."

"A 3D image was then created by combining images from the four detectors using a well-known technique called "shape from shade"."

This 3D computational imaging, or ghost imaging produces detailed images of objects in just a few seconds.

Conventional 3D imaging systems uses multiple digital camera sensors to produce a 3D image from 2D information. Careful calibration is required to ensure the multi-megapixel images align correctly.

Beyond the visible
Prof Padgett continued: "Our single-pixel system creates images with a similar degree of accuracy without the need for such detailed calibration."

Baoqing Sun

Lead author on the paper Baoqing Sun said: "It might seem a bit counter-intuitive to think that more information can be captured from a detector which uses just a single pixel rather than the multi-megapixel detectors found in conventional digital cameras.

"However, digital camera sensors have a very limited sensitivity beyond the spectrum of visible light, whereas a single-pixel detector can easily be made to capture information far beyond the visible, reaching wavelengths from X-ray to TeraHertz."

More Information:
The team's paper, 3D Computational Imaging with Single-Pixel Detectors, is published in the Science 17 May 2013: Vol. 340 no. 6134 pp. 844-847 DOI:10.1126/science.1234454.