Microsoft has become the latest company to show its hand in the race to gain the image quality benefits of curved sensors. Its Project Vermont has developed a method for bending conventionally made silicon sensors into more uniformly-curved shapes.

We've reported several times over the past few years on various commercial and academic projects working towards the creation of curved sensors. Curved sensors promise several image quality improvements: they can work with simpler lenses, since you don't need to optically correct a curved projection to a flat surface, they also give more direct illumination to pixels at the edges of the sensor, improving how much light they can receive. There's also a benefit at the center, possibly stemming from better acceptance of light from the edge of the lens.

In a paper published in the journal Optics Express (doi:10.1364/OE.25.013010), the group discusses a method for bending conventional silicon sensors in a way that gives a more even, rounded curvature. The process was refined to the point that it took only a couple of minutes to curve the sensor and maintain the curvature.

The paper discusses the creation of a curved sensor based on an Aptina 1/2.3" type sensor and its performance, it also discusses the modelled benefits of sensors with curvatures to match lenses ranging from 30mm equiv to 80mm equiv, vs the performance of similar flat sensors.

The team also compared the performance of its curved sensor and lens to a flat version of the same chip with a commercially available 6mm F1.2 lens. These, in turn, were compared with the performance of a Canon 50mm F1.2 lens on EOS-1D S Mark III. The simpler lens on the curved sensor gave significantly more consistent across-the-frame performance than either conventional lens and flat sensor combination.

The group list photography, videography, computer vision and automation, reconnaissance and surveillance imaging, microscopes, and telescopes as being some of the fields that could benefit from curved sensors, though the issue remains that the curvature needs to be matched to the focal length of the lens, limiting their benefits to systems with fixed focal lengths, unless the curvature can be varied.