CU News
News from the University of Colorado in Boulder.
CU study: Bug-eyed lenses capture wide view with no distortion
May 1st
Lenses shaped like the bulging, bowl-shaped eyes possessed by dragonflies, praying mantises, houseflies and other insects can take exceptionally wide-angle photos without distorting the image.
To create the innovative camera, which also allows for a practically infinite depth of field, the scientists used stretchable electronics and a pliable sheet of microlenses made from a material similar to that used for contact lenses. The researchers described the camera in an article published today in the journal Nature.
Conventional wide-angle lenses, such as fisheyes, distort the images they capture at the periphery, a consequence of the mismatch of light passing through a hemispherically curved surface of the lens only to be captured by the flat surface of the electronic detector.
For the digital camera described in the new study, the researchers were able to create an electronic detector that can be curved into the same hemispherical shape as the lens, eliminating the distortion.
“The most important and most revolutionizing part of this camera is to bend electronics onto a curved surface,” said Jianliang Xiao, assistant professor of mechanical engineering at CU-Boulder and co-lead author of the study. “Electronics are all made of silicon, mostly, and silicon is very brittle, so you can’t deform the silicon. Here, by using stretchable electronics we can deform the system; we can put it onto a curved surface.”
Creating a camera inspired by the compound eyes of arthropods — animals with exoskeletons and jointed legs, including all insects as well as scorpions, spiders, lobsters and centipedes, among other creatures — has been a sought-after goal. Compound eyes typically have a lower resolution than the eyes of mammals, but they give arthropods a much larger field of view than mammalian eyes as well as high sensitivity to motion and an infinite depth of field.
Compound eyes consist of a collection of smaller eyes called ommatidia, and each small eye is made up of an independent corneal lens as well as a crystalline cone, which captures the light traveling through the lens. The number of ommatidia determines the resolution and varies widely among arthropods. Dragonflies, for example, have about 28,000 tiny eyes while worker ants have only in the neighborhood of 100.
Imitating the corneal lens-crystalline cone pairings, the camera created by Xiao and his colleagues has 180 miniature lenses, each of which is backed with its own small electronic detector. The number of lenses used in the camera is similar to the number of ommatidia in the compound eyes of fire ants and bark beetles.
The electronics and the lenses are both flat when fabricated, said Xiao, who began working on the project as a postdoctoral researcher in John Roger’s lab at the University of Illinois at Urbana-Champaign. This allows the product to be manufactured using conventional systems.
“This is the key to our technology,” Xiao said. “We can fabricate an electronic system that is compatible with current technology. Then we can scale it up.”
The lens sheet and the electronics sheet are integrated together while flat and then molded into a hemispherical shape afterward. Each individual electronic detector and each individual lens do not deform, but the spaces between the detectors and lenses can stretch and allow for the creation of a new 3-D shape. The electronic detectors are all attached with serpentine filament bridges, which are not compromised as the material stretches and bends.
In the pictures taken by the new camera, each lens-detector pairing contributes a single pixel to the image. Moving the electronic detectors directly behind the lenses — instead of having just one detector sitting farther behind a single lens, as in conventional cameras — creates a very short focal length, which allows for the near-infinite depth of field.
The new paper demonstrates that stretchable electronics can be used as the foundation for a distortion-free hemispherical camera, but commercial production of such a camera may still be years away, Xiao said.
The three other co-lead authors of the paper are Young Min Song, Yizhu Xie and Viktor Malyarchuk, all of the University of Illinois. Other co-authors are Ki-Joong Choi, Rak-Hwan Kim and John Rogers, also of Illinois; Inhwa Jung, of Kyung Hee University in Korea; Zhuangjian Liu, of the Institute of High Performance Computing A*star in Singapore; Chaofeng Lu, of Zhejiang University in China and Northwestern University; Rui Li, of Dalian University of Technology in China; Kenneth Crozier, of Harvard University; and Yonggang Huang, of Northwestern University.
The research was funded by the Defense Advanced Research Projects Agency and the National Science Foundation.
CU news release
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As the planet warms faster, more species will be increasingly at risk
Apr 21st
The Earth’s climate zones are shifting at an accelerating pace, says a new study led by a scientist at the CU’s Cooperative Institute for Research in Environmental Sciences.
The acceleration of change means that the species inhabiting each zone have less time to adapt to the climatic changes, said lead author Irina Mahlstein, a CIRES scientist who works at NOAA’s Earth System Research Laboratory in Boulder, Colo. “The warmer the climate gets, the faster the climate zones are shifting. This could make it harder for plants and animals to adjust.”
The study is the first to look at the accelerating pace of the shifting of climate zones, which are areas of the Earth defined by annual and seasonal cycles of temperature and precipitation, as well as temperature and precipitation thresholds of plant species. Over 30 different climate zones are found on Earth; examples include the equatorial monsoonal zone, the polar tundra zone and cold arid desert zone.
“A shift in the climate zone is probably a better measure of ‘reality’ for living systems, more so than changing temperature by a degree or precipitation by a centimeter,” said Mahlstein.
The scientists used climate model simulations and a well-known ecosystem classification scheme to look at the shifts between climate zones over a two-century period, 1900 to 2098. The team found that for an initial 3.6 degrees Fahrenheit of warming, about 5 percent of Earth’s land area shifts to a new climate zone.
The models show that the pace of change quickens for the next 3.6 F of warming as an additional 10 percent of the land area shifts to a new climate zone. The paper was published online in the journal Nature Climate Change on April 21.
Certain regions of the globe, such as northern middle and high latitudes, will undergo more changes than other regions, such as the tropics, the scientists found. In the tropics, mountainous regions will experience bigger changes than low-altitude areas.
In the coming century, the findings suggest that frost climates — the coldest climate zone of the planet — will largely decrease. In general, dry regions in different areas of the globe will increase, and a large fraction of land area will change from cool summers to hot summers, according to the study.
The scientists also investigated whether temperature or precipitation had a greater impact on how much of the land area changed zones. “We found that temperature is the main factor, at least through the end of this century,” said Mahlstein.
John Daniel at the NOAA Earth System Research Laboratory and Susan Solomon at the Massachusetts Institute of Technology co-authored the study.
-CU press release
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CU math whizzes are at the top of the heap
Apr 17th
Outstanding winners of international competition, again
Two University of Colorado Boulder undergraduate student teams have been named among the 11 top winners from a field of 5,636 teams that entered the 2013 international Mathematical Contest in Modeling this spring.
Only 375 teams, or 6 percent of those entering the contest, were from the United States. The others were from Canada, China, Finland, Germany, Hong Kong, India, Indonesia, Ireland, Mexico, Malaysia, Singapore, South Korea, Sweden and the United Kingdom.
CU-Boulder undergraduate students, from left to right, Fiona Pigottt, Tracy Babb, Christopher Aicher, Gregory McQuie, Yueh-Ya “Sam” Hsu and David Thomas join faculty adviser Anne Dougherty, at center in front row, to celebrate their being named “Outstanding Winners” in the 2013 Mathematical Contest in Modeling. (Photo by Casey A. Cass/University of Colorado)
CU-Boulder had two teams designated as “Outstanding Winners” in 2012 as well, and has had a total of 13 Outstanding Winner designations since 2000.
“I don’t know any other university, from anywhere in the world, that has that track record,” said Anne Dougherty of CU-Boulder’s Department of Applied Mathematics. “This is a testament to our excellent students and exceptionally strong undergraduate program.”
One of the 2013 problems focused on developing an effective, feasible and cost-efficient strategy to meet projected water needs in a given country, while the other challenged students to develop the “ultimate brownie pan” to maximize heat distribution and cooking potential in an oven.
Results of the contest, which took place at the students’ home institutions Jan. 31-Feb. 4, were announced by the Consortium for Mathematics and its Applications on April 5.
One of the two CU-Boulder teams designated as an “Outstanding Winner” was comprised of students Gregory McQuie and David Thomas of aerospace engineering sciences, and Yueh-Ya Hsu of applied mathematics. The team also was awarded the Mathematical Association of America Award.
The other “Outstanding Winner” from CU-Boulder included students Christopher Aicher and Tracy Babb of applied mathematics, and Fiona Pigott, who is double-majoring in mechanical engineering and applied mathematics. The team also was presented with the Society for Industrial and Applied Mathematics Award.
Dougherty served as faculty adviser to both teams. Any undergraduate CU-Boulder student was welcome to participate.
A third team of CU-Boulder students entered the contest and was designated a “successful participant.” That team included students Runnan Lou of aerospace engineering, Weiming Zhang of applied mathematics and Xinyu Shen, who is double-majoring in math and physics.
According to the contest rules, the students had 96 hours to decide which of two problems to complete, research their problem, come up with a mathematical model, program a numerical model and write a report.
Official contest results are posted at http://www.comap.com/undergraduate/contests/mcm/contests/2013/results.
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