Thursday, February 23, 2012

Holography essay for The DuPont Challenge

This is an essay i wrote for The DuPont Challenge, for it's annual science essay competition.
            Our world today is quite different from what people in the past thought it would be. They might have expected that by now we would have flying cars and vacations in space, or we’d be bouncing around the world by teleport. [1] Today we do, however, possess emerging technology that may soon make holographic video a reality.
            When one thinks of holograms, Princess Leia’s desperate plea for help against an evil galactic empire may spring to mind.  This 35 year old idea is on its way to becoming a reality. We've come a long way since the first static holograms were transmitted over a television system in 1966.Scientists at the University of Arizona in Tucson are in the midst of developing a new kind of viewing technology that promises to surpass the much anticipated 3D television. [2] With three dimensional television one sees two separate images: each eye sees a separate image and the two are combined within the brain to create the illusion of depth. But with a holographic television you would view 180 degrees of whatever image was being projected. In the near future the general population might be trading in their flat screen plasma television sets for a brand new kind of home entertainment system using holograms.
                To make holographic recordings scientists are using a technique called stereographic holography that has substantially decreased the data load and number crunching required to process holographic digital information. This is the root of what makes holographic movies possible. The basis of this technology is that one image printed on a plastic based composite can be rapidly erased and another three dimensional image rewritten in its place. [3] The composite is called a photoreactive polymer, a plastic coated with a material that converts light into electrical charges to store the image. The electrical charges imprint the optical data onto the material to produce a realistic, three dimensional image. This kind of fast paced rewriting technique has never been used before. The process of putting holographic images onto the plastic display starts with 16 cameras arranged in a semi -circle all capturing different vantage points of an object in the middle. Then a flash of safe laser light is blasted, much like the flash from light on a camera. This process is recorded digitally.
                After the image is recorded it gets transmitted via wireless or Ethernet cable to the display unit, where it appears on the photorefractive polymer. This kind of new technology could drastically improve telepresence, which can be thought of as a more physically realistic version of  Skype, Face Time, or Face Chat for Facebook.  Imagine someone seeming to be actually in the room with you instead of just a face on a computer screen. This has the potential to be “the next big thing” and can revolutionize business meetings, doctor-patient consultations, or military applications. Holography could have applications in spying, guiding weapons, or any number of other defense applications.
                As of now the refresh time of holography is around two seconds, already cut down from four minutes from previous experiments at the University of Arizona. Hopefully in the near future that time will be cut down to 30 frames per second, the standard refresh time for video.
                It is the chemical composition of the polymer that makes the whole system possible. The polymer is made by melting a composite between two glass plates. The structure and composition of the polymer is a copolymer with a polyacrylic back bone that was used to attach other chemical groups. A chromophore is added to the compound to make the end product able to absorb and emit visible light. This increases refractive index change, which in turn allows the information of the holographic image to be written. The hologram is written by successively recording approximately 120 holographic pixels, or “hogels,” side by side.  After this, a plasticizer is added aswell. The whole composite is chemically stable. Samples have been able to withstand use for months and hundreds of rewrites without degeneration occurring. [4]
                “This is mostly a materials advance,” says optical scientist Michael Bove of the MIT Media Lab. “The material is faster and more sensitive than what had previously been reported.” [1]
                Within the next several years it is hoped that researchers will have completed at least a prototype of a video quality moving hologram.

"It took us a while to make that first breakthrough, but as soon as you have the first element of it working the rest often comes more rapidly. What we are doing now is trying to make the model better,” says Nasser Peyghambarian, chair of photonics and lasers at the University of Arizona’s Optical Sciences department. [5] As for myself, I have a strong interest in the field of Optics and plan to attend the University of Arizona as well. And who knows, in the future I may take part in making this vision of holography possible.

820 words


1. Lisa Grossman, (November 3, 2010), Wired Science, Holographic Telecommuting May Soon be Possible, (www.wired.com/wiredscience.2010/11/holographic-video/)
2. Stewart Bland, (December 16, 2010), Materials Today, Coming Soon to a Screen near You, (www.materialstoday.com/view/14710/coming-soon-to-a-screen-near-you/)
3. P.A Blanche, A. Bablumlan, R. Voorakaranam, C. Christenson, W. Lin, T.Gu, D. Flores, P. Wang, W.-Y. Hsleh, M. Kathapeumal, B. Rachwal, O. Sklddiqul, J. Thomas, R.A. Norwood, M. Yamamoto & N. Peyghambarian, (November 4, 2010), Nature, Holographic Three-Dimensional Telepresence Using Large-Area Photorefractive Polymer, Vol 468, pages 80-83
4. Jayan Thomas, Cory W. Christenson, Pierre-Alexandre Blance, Michiharn Yamamoto, Robert A. Norwood, Nasser Peyghambarian, ( 2011), Chemistry of Materials, Photoconducting Polymers for Photorefractive 3D Display Applications, Issue 23, pages 416-429
5.Mike Steere, (October 7, 2008), CNN.com/technology, Scientist: Holographic Television to Become Reality, (http://articles.cnn.com/2008-10-06/tech/holographic.television_1_holographic-displays-hologram-technology?_s=PM:TECH)