PFCA - The Smallest camera in the world & it has got no lens !!!

Tiny Camera Captures Images without Lenses

Patricia Daukantas

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 The planar Fourier capture array takes images from an array of angle-sensitive pixels. For example, the camera reconstructed an image of the Mona Lisa.

Researchers at Cornell University (U.S.A.) have developed a tiny electronic camera that captures images without using lenses to focus the incoming light. The imager, made through a standard semiconductor fabrication process, has no moving parts and is less than 1 square millimeter in size and about 10 µm thick (Optics Letters, posted online July 7, document ID 147442).

From the earliest pinhole cameras to today’s digital cameras, far-field imaging systems have relied on lenses and mirrors to focus the light onto a sensor plane, and that optical path length has limited how small these instruments can be made. Instead of lenses, the Cornell camera consists of a silicon chip with two side-by-side 38 × 38 pixel arrays, each covered with two layers of diffraction gratings. These gratings make the pixels sensitive to the angle of the incoming light, and each pixel records a slightly different view of the scene.

Alyosha Molnar, Patrick Gill and their colleagues in Cornell’s electrical and computer engineering department call their device a planar Fourier capture array, or PFCA, because it relies on off-chip Fourier transform calculations to make sense of the camera data.

To fabricate the array, the team used the 180-nm complementary metal-oxide-semiconductor (CMOS) process, which limited the array size to 38 × 38. With the grating period ranging from 0.6 to 1.4 µm, the PFCA is optimized for 520-nm (green) light; the grating size would need to be increased to pick up red light.

Although the tiny array will never rival today’s megapixel cameras in picture quality, Molnar and Gill say that the technology bridges the gap between the smallest commercially available cameras with focusing optics and the individual photodiode or pixel, which records only brightness without image data.

According to Gill, who started working with Molnar when they were graduate students at the University of California at Berkeley, the PFCA would cost pennies to manufacture and could work in weight- and size-sensitive imaging applications. “The most exciting uses are probably things we haven’t thought of yet,” he said.