To create their lens-less camera, the researchers placed an image sensor (with no lens) on the edge of a transparent window and used it to form images of an object seen through that window. This, they say, is enabled by both the collection of scattered light by the image sensor and by the solution of an inverse problem that represents the light scattering process.

Previously, cameras have been developed based on the idea that humans will look at and decipher the pictures. However, the researchers wondered, what if a camera was developed that can be interpreted by a computer running an algorithm?

“Why don’t we think from the ground up to design cameras that are optimized for machines and not humans,” says electrical and computer engineering associate professor Rajesh Menon. “That’s my philosophical point.”

If pointed at an object without a lens, a normal digital camera sensor results in an unrecognizable pixelated image. However, say the researchers, there is still enough digital information within that image to detect the object if a computer program is properly trained to identify it – it simply means creating an algorithm to decode the image.

In experiments, the researchers took a picture of the university’s “U” logo as well as video of an animated stick figure – both displayed on an LED light board – using an off-the-shelf camera sensor. The sensor was connected to the side of a plexiglass window, but pointed into the window while the light board was positioned in front of the pane at a 90-degree angle from the front of the sensor.

The resulting image from the camera sensor, with help from a computer processor running the algorithm, is a low-resolution picture but definitely recognizable. The method also can produce full-motion video as well as color images, say the researchers.

The process involves wrapping reflective tape around the edge of the window. Most of the light coming from the object in the picture passes through the glass, but just enough — about 1% — scatters through the window and into the camera sensor for the computer algorithm to decode the image.

The resulting photo, say the researchers, while not high resolution, would be good enough for applications such as obstacle-avoidance sensors for autonomous cars. However more powerful camera sensors would be able to produce higher-resolution images.

Applications for such a lens-less camera, say the researchers, could be almost unlimited. For example, security cameras could be built into a home during construction by using the windows as lenses, or such cameras could be used in augmented-reality (AR) goggles to reduce their bulk.

A car windshield could have multiple cameras along the edges to capture more information. And the technology could also be used in retina or other biometric scanners, which typically have cameras pointed at the eye.

Going forward, the researchers plan to further develop the system, including producing 3D images, higher color resolution, and photographing objects in regular household light. For more, see “Computational imaging enables a “see-through” lens-less camera .”

Related articles:
Lensless ‘camera of the future’ opens new imager applications
Lensless camera adjusts focus after image capture
Lens-free flat camera addresses emerging imaging applications
Microsoft curved image sensor promises ‘ideal’ camera

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