Microsoft curved image sensor promises ‘ideal’ camera

Technology News | June 12, 2017

By Rich Pell

Optoelectronics Sensing / Conditioning Materials & processes

The new approach would improve upon the flat image sensors found in current cameras, which use multiple optical elements in their lenses to optimize and adjust the image so that it can be read by the flat sensor. Curved image sensors would need fewer such corrections, and allow the use of fewer optical elements.

Curved image sensors, say the researchers, make 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. It is also more straightforward to make cameras that exhibit uniform illumination across the entire image.

“Our approach to curving commercially available image sensors could make it possible to have a new class of camera that would be very small, but have image quality that would be comparable to image sensors found in much larger cameras,” says Brian Guenter, leader of the Microsoft Research team. “In addition to improving consumer cameras, curved sensors could be used to create better cameras for surveillance, head-mounted displays, and advancements in autonomous vehicle navigation.”

To make the curved sensors, the researchers placed individual sensors cut from a thinned CMOS image sensor wafer into custom-made molds and then used pneumatic pressure to push each sensor down into the mold. HRL Laboratories, which has semiconductor fabrication capabilities and equipment, was contracted to help solve some of the specific physics challenges involved in bending the sensors.

The researchers reported that their new method can create image sensors with three times more spherical curvature than previously possible, and they are working to see if further improvements might produce sensors with even more curvature. A prototype camera incorporating one of their sensors produced higher resolution images across the entire field of view compared to high-end commercial single-lens reflex (SLR) cameras.

“Although the benefits of using curved sensors have been known for some time, our work now makes it practical to create cameras with curved sensors,” says Richard Stoakley, a member of the research team. “Adding spherical curvature to an off-the-shelf image sensor can be done for a reasonable cost and in a way that shows significant benefits.”

The researchers say that the lenses could be made small enough for mobile phones and tablets. They are also hoping to experiment with curving sensors that operate in infrared wavelengths, which could find use in telescopes, 3D spatial mapping, biometric authentication, and a number of scientific applications.

“I think we have opened the door for an entirely new class of lenses,” says Stoakley. “I’m excited to see how our group and others use curved sensors to achieve even more improvements in camera quality through innovative lens design.”

Commercial products using the curved sensors are not likely to appear soon, say the researchers, but they are looking to work with companies to further improve and test the sensors to prepare for potential mass production.

For more, see “Highly curved image sensors: a practical approach for improved optical performance.”