Over the past several years, researchers from both industry and academia have been probing the possibilities of using curved image sensors in imaging devices. The latest to publish their findings is a team from Microsoft and HRL Laboratories who have created a curved sensor design that they say can be mass produced for small cameras and, eventually, mobile phones.
While companies like Sony have made progress toward building curved sensors, the manufacturing process is extremely difficult. What Microsoft and HRL discovered was a method to take off-the-shelf sensors and gradually and gently bend them into the desired, curved shape. (If you want the gory details, hit the link above.)
A curved sensor bestows several potential benefits for cameras and particularly lenses. Many of the optical elements used by lens manufacturers are in place to correct optical distortions and bend light so that it can land on a flat sensor. With a curved sensor, you should be able to ditch the lens elements responsible for flattening an image and also the elements used to correct distortions introduced by the flattening elements. The result is not simply lighter and smaller lenses, but higher quality ones at that.
“When using curved sensors, it is possible to correct aberrations in a much more efficient way, making it easier to create very wide angle lenses that produce sharp images across the entire field of view or to create fast lenses that produce better images in low light,” said Neel Joshi, a member of the research team in a statement. “It is also more straightforward to make cameras that exhibit uniform illumination across the entire image.”
When Microsoft’s team tested their sensor on a prototype camera with a specially designed f/1.2 lens, they say their curved sensor “exhibited a resolution more than double that of a high-end SLR camera with a similar lens.” That lens in question was a Canon 50mm f/1.2 lens.
According to the researchers, “Our curved camera prototype maintains near perfect consistency in illumination, losing only 1 percent of the illumination of the corner relative to the center.” Toward the edges of the image, the Microsoft team found that the curved sensor was about five times sharper than Canon’s DSLR lens. They also found nearly no loss of light at the edge of the sensor, while the Canon lens lost about 90 percent of its light at the edges.
Microsoft says their sensor bending technique is “scalable to any die size, optically precise even for fast lenses, and compatible with cost effective, large scale manufacturing processes.” Of course, considering the substantial investment the photo industry has made in creating flat sensors and the lenses to accommodate them, we probably shouldn’t expect a wholesale shift to curved sensors anytime soon. But it appears to be a tantalizing possibility for the medium-term future.
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