Computer
scientist Shree K. Nayar from the Columbia University has invented the
world’s first fully self-powered video camera that can produce an image
each second, indefinitely, of a well-lit indoor scene.
Nayar
designed a pixel that not only can measure incident light (a ray of
light that strikes a surface) but also convert the incident light into
electric power.
“We
are in the middle of a digital imaging revolution. A camera that can
function as an untethered device forever — without any external power
supply — would be incredibly useful,” said Nayar, who heads the computer
vision laboratory at the Columbia Engineering.
At
the heart of any digital camera is an image sensor, a chip with
millions of pixels. The key enabling device in a pixel is the photodiode
which produces an electric current when exposed to light. The
photodiode in a camera pixel is used in the photoconductive mode while
in a solar cell it is used in the photovoltaic model.
This mechanism enables each pixel to measure the intensity of light falling on it.
Nayar,
working with research engineer Daniel Sims, and consultant Mikhail
Fridberg of the consultancy firm ADSP Consulting used off-the-shelf
components to fabricate an image sensor with 30×40 pixels.
In
Nayar’s prototype camera, which is housed in a 3D printed body, each
pixel’s photodiode is always operated in the photovoltaic mode. When the
camera is not used to capture images, it can be used to generate power
for other devices, such as a phone or a watch.
According to Nayar, the image sensor could use a rechargeable battery and charge it via its harvesting capability.
“But
we took an extreme approach to demonstrate that the sensor is indeed
truly self-powered and used just a capacitor to store the harvested
energy,” he noted.
“We
believe our results are a significant step forward in developing an
entirely new generation of cameras that can function for a very long
duration — ideally, forever — without being externally powered,” the
authors wrote.
The
team is set to present its work at the international conference on
computational photography at the Rice University in Houston April 24-26.
Posted by : Gizmeon
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