This story is from the category Sensors
Date posted: 09/08/2008
Traditional cameras and optical sensors have many shortcomings when compared to the organic eyeball. Artificial variants cannot cope simultaneously with a range of luminescent views, they cannot focus on differing focal lengths in the same image, and they cannot give a panoramic view like a natural eye, without distortion.
Well, that last point might well be conquered. A new breed of curved optical sensors mimics the shape of the eyeball, and in doing so, eliminates the distortion curve with panoramic images.
Its not quite at the stage of human implantation use yet; initial uses are for cameras and external sensor systems. However, since the process involves encasing the eye in a glass ball, it will beyond doubt prove a suitable design for replacing existing camera sensors in eye replacement as well.
The curve has been accomplished utilising an array of photodiodes bound flexibly with wire, that is then engraved on curved silicon created with a new method. The problem with making silicon curve, is that silicon does not naturally bend easily and cannot be forced into a hemispherical form without creases appearing in the material.
John Rogers at the University of Illinois at Urbana-Champaign and colleagues have now worked out a way around those problems, using conventional chip manufacturing technology.
They built their hemispherical electronic eye by first using conventional photolithography to build silicon photodiodes 500 micrometers square and 1 micrometer thick. These were then wired into a flexible 16-by-16 array using chromium and gold.
Separately, they created a 1-cm-wide hemisphere out of a stretchy plastic, and stretched it into a flat surface. That stretched surface, or "drumhead", was then pressed against the photodiode array.
The reformed array was then glued to a curved glass surface, and a conventional lens attached. It now resembled a human eye in construction, with light entering the lens from the front, and passing to the curved "retina" containing the matrix of photodiodes behind.
Although the camera they created has only 256 pixels and is therefore relatively low-resolution, Rogers says that the same technique could be used to make wide-angle megapixel cameras.
See the full Story via external site: technology.newscientist.com
Most recent stories in this category (Sensors):
11/12/2013: Swarming insect provides clues to how the brain processes smells