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Holograms taken to new dimension

echnology developed by a team of University of Utah electrical and computer engineers could make the holographic chess game R2-D2 and Chewbacca played in “Star Wars” a reality. The team led by electrical and computer engineering associate professor Rajesh Menon has discovered a way to create inexpensive full-color 2-D and 3-D holograms that are far more realistic, brighter and can be viewed at wider angles than current holograms. The applications for this technology could be wide-ranging, from currency and identification badges to amusement rides and advertisements. “You can have rich colors at high efficiency, with high brightness and at low cost. And you don’t need fancy lasers and complicated optics,” Menon says. The team’s technology was profiled in a new paper published July 19, 2017, in the current issue of Scientific Reports. The paper, “Full Color, Large Area, Transmissive Holograms Enabled by Multi-Level Diffractive Optics,” was co-authored by University of Utah doctoral students Nabil Mohammad, Monjurul Meem and Xiaowen Wan. Typically, the projection of any image, whether it is two or three dimensional, is inefficient because when white light shines on an object, we can only see the reflected color that bounces back to our eyes while the rest of the colors of the spectrum are absorbed. Therefore, there is a lot of wasted light. With a typical LCD projector, for example, you may only see as little as 5 percent of the total light at one time. Menon and his team have discovered a better way that borrows from the same principle behind how wings of certain butterflies display their colors: Instead of reflecting only the colors you see while absorbing the rest, all of the white light is redirected so you see the wavelengths of the wing’s colors at different locations. None of the light is absorbed and therefore wasted. Using sophisticated algorithms and a new fabrication method, the engineers can create holograms that do the same thing — redirect colors to appropriate locations — instead of absorbing most of it to project much brighter photographic images either in 2-D or 3-D and with full, natural colors. Currently, full-color holograms require lasers to not only make them, but also to view them. Menon’s holograms can be viewed with regular white light. Most importantly, these holograms can be viewed from any angle, and the image detail does not change, much like a real object.”

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