Researchers at the University of Illinois at Urbana-Champaign have added zoom capability to their ground-breaking "human eye" camera that I initially wrote about a couple of years ago.
The human eye camera attempts to mimic the human eye's ability to see by using a curved image sensor. When the camera takes a photo with this technology, the image is recorded by a series of silicon detectors and electronics that conform to the curved surface of the image sensor ... similar to the curved area in the back of the human eye that’s the focal point for light entering the eye.
The curved image sensor provides improved image quality at the edges of the photo versus a flat image sensor, because the light is curved as it enters the eye -- or a lens -- and by matching the curvature of the receptor to the curvature of the light, image quality is better.
The latest improvement in the human eye camera is the ability to add zoom capabilities, according to a recent announcement from the researchers.
Northwestern professors Yonggang Huang and Joseph Cummings teamed with Professor John Rogers of the University of Illinois to create the original curved image sensor, and they’ve teamed together on adding the zoom capability to their original design.
The zoom function works because the image sensor’s curvature angle changes to allow for a variety of magnification levels. The array of photodetectors must be tuned to meet the proper curvature to match a particular zoom measurement. The researchers say they use hydraulics to pull or push the photodetector array membrane (which is similar to a stretched sheet of latex) into the proper curvature for each zoom measurement.
The membrane sits atop a water chamber, and a clear glass window is underneath. Initially, the membrane is flat. When the curvature is needed, water is pulled out of the chamber, causing the membrane to curve (becoming a concave hemisphere). Replacing the water causes the membrane to flatten again.
Additionally, the system allows water to be injected into the lens chamber, which causes the membrane to become a convex hemisphere.
The current zoom is equal to about a 3.5X optical zoom lens, but a larger zoom will be possible, the researchers say.
"This provides a key piece of missing functionality for the original camera concept," Rogers says. "The result is a complete camera system, with tunable lens and tunable detector, capable of taking pictures."
Eventually, the curved image sensor could appear in digital cameras and cell phones, aiming to provide much improved overall image quality, although initial applications likely include night-vision surveillance, robotic vision, and endoscopic imaging.
However, the researchers still have several hurdles to overcome to approach the capabilities of today’s flat image sensors. For example, the human eye camera is too large for use in a typically sized camera. However, the researchers say, a curved image sensor will require fewer image management components than what is required for flat image sensors, meaning -- eventually -- the curved image sensor cameras could be smaller, thinner, and lighter than flat image sensor cameras.
Additionally, the camera's resolution is only a few hundred pixels, well below the 16 megapixels of resolution (or 16 million pixels) that are appearing in 2011's consumer-level digital cameras.
Still, the research will continue, and we many eventually have an opportunity to use human eye cameras in our everyday lives.
"We were inspired by the human eye, but we wanted to go beyond the human eye," Huang says. "Our goal was to develop something simple that can zoom and capture good images, and we've achieved that."
