Miniature cameras can be found in billions of smartphones as well as countless other modern devices. However, the physics of the lenses prevents them from getting any smaller. An age-old principle that can be found in nature may be the answer.
There is plenty going on in Jena, the “optical” capital of the world. Where physicist Ernst Abbe first performed precise calculations for microscope optics in 1870, now Zeiss, Jenoptik SCHOTT and the Fraunhofer Institute for Applied Optics and Precision Mechanics (IOF) have set up shop. On the outskirts of Jena, everyone is devoted to artificial eyes. And they haven’t been using the human eye as a blueprint for quite some time.
While classic solutions would have the image “pass through” a single curved lens, for more than ten years now Fraunhofer researchers have been experimenting with an entire line of lenses the size of a corn of sand that only ever provide a certain small piece of the image. Then the software of the facet-eye camera takes care of the overall image.
The facet-eye camera of the fruit fly
One of the models used comes from biomedicine’s favorite workhorse, the fruit fly drosophila melanogaster. With an overall length of just three millimeters, there isn’t a lot of room for an eye. The solution: Lots of tiny lenses, in the simplest case each with a “sensor” behind it: Unbeatably small, a large field of vision and high sharpness of motion. However, the weakness of the arrangement is the resolution. Nature solved that problem over the course of a few million years: More lenses—higher resolution. So dragonflies, which have 28,000 individual eyes, get a very good impression of their surroundings.
The folks at Fraunhofer IOF didn’t need quite as much time. While a 0.4-millimeter thick prototype had a resolution of 60 x 60 pixels in 2004, the recently introduced facetVISION camera is approximately 2 millimeters thick and has a resolution of one megapixel. By offsetting each of the 135 microlenses to their associated aperture, each optical channel has an individual viewing direction and always depicts another portion of the field of vision. The chips are only half as thick as conventional smartphone cameras and have no moving parts, which makes them fast, sturdy and energy efficient.
The Fraunhofer Institute for Integrated Circuits (IIS) joined the party in 2010. Resolutions of up to four megapixels will supposedly be possible in the future. And that is considerably more than the cameras currently being used in robotics or automobile manufacturing.
Mass production on wafers
The cost-effective manufacturing techniques—similar to those used in the semiconductor chip industry—also speak in favor of the facet-eye camera. However, before it makes its way into smartphones, it would have to be adapted because the camera optics used there are manufactured using plastic injection molding. Multiple small lenses could even be placed next to one another in the smartphone camera. That would make it possible to reach resolutions of more than 10 megapixels with a camera thickness of just three and a half millimeters or even 20 megapixels with a thickness of five millimeters. And the “camera bump” on ultrathin smartphones would be a thing of the past.
Artificial “insect eyes” are still unable to measure themselves against the resolutions of current smartphone cameras. But quite a bit has happened in the past ten years. We’re getting a handle on the technology, production is becoming economically feasible and the advantages are obvious. What do you think? Will smartphones soon feature facet-eye cameras?