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Moving 3D images may be inching toward real-life use

Nov. 3, 2010
Courtesy of the University of Arizona
and World Science staff

Re­mem­ber the Star Wars scene in which R2D2 pro­jects a three-di­men­sion­al im­age of a trou­bled Prin­cess Leia de­liv­er­ing a call for help to Luke Sky­walker and his al­lies? 

Sci­en­tists now claim that the science-fiction con­cept of 3D mov­ing pictures is ap­proach­ing real­ity, thanks to a break­through in 3D hol­o­graph­ic im­ag­ing tech­nol­o­gy.

A re­search team led by Uni­vers­ity of Ar­i­zo­na op­ti­cal sci­ent­ist Nas­ser Peygham­bar­ian has de­vel­oped a de­vice that al­lows the pro­jec­tion of a 3D, mov­ing im­age with­out the need for spe­cial glass­es or oth­er aux­il­ia­ry de­vices. The tech­nol­o­gy is likely to take ap­plica­t­ions rang­ing from telemedicine, ad­ver­tis­ing, up­dat­able 3D maps and en­ter­tain­ment to a new lev­el, the de­vel­op­ers pre­dict. 

A holo­graph­ic im­age of an F-4 Phan­tom Jet crea­ted on a pho­to­re­frac­tive poly­mer at the Col­lege of Op­tic­al Sci­ences at the Uni­ver­s­ity of Ari­zona. (ga­rgasz­pho­tos.com/U. Ari­z­ona)


The jour­nal Na­ture chose the tech­nol­o­gy to fea­ture on the cov­er of its Nov. 4 is­sue.

“At the heart of the sys­tem is a screen made from a nov­el pho­tore­frac­tive ma­te­ri­al, ca­pa­ble of re­fresh­ing holo­grams eve­ry two sec­onds, mak­ing it the first to achieve a speed that can be de­scribed as quasi-real-time,” said Pierre-Alex­andre Blanche of the uni­vers­ity, lead au­thor of the Na­ture re­port. A pho­tore­frac­tive ma­te­ri­al is one that can have var­y­ing light-bend­ing prop­erties de­pend­ing on the light hit­ting it.

The pro­to­type de­vice uses a 10-inch screen, but Peygham­bar­ian’s group is test­ing a ver­sion with a 17-inch screen. 

The im­age is recorded us­ing an ar­ray of reg­u­lar cam­er­as, each of which views the ob­ject from a dif­fer­ent per­spec­tive. That in­forma­t­ion is then en­cod­ed on­to a fast-pulsed la­ser beam, which in­ter­feres with anoth­er beam that serves as a ref­er­ence. The re­sult­ing in­ter­fer­ence pat­tern is writ­ten in­to the pho­tore­frac­tive pol­y­mer, or plastic-like mat­er­ial, that cre­ates and stores the im­age. 

Each la­ser pulse records an in­di­vid­ual “hogel” in the pol­y­mer. A hogel, short for hol­o­graph­ic pix­el, is the three-di­men­sion­ ver­sion of a pix­el, the bas­ic un­its that make up the pic­ture.

The ho­lo­gram fades nat­u­rally af­ter a cou­ple of min­utes or sec­onds. It can also be erased by re­cord­ing a new 3D im­age, cre­at­ing a new dif­frac­tion struc­ture and de­let­ing the old pat­tern.

“Let’s say I want to give a pre­s­enta­t­ion in New York,” Peygham­bar­ian ex­plained. “All I need is an ar­ray of cam­er­as here in my Tuc­son of­fice and a fast In­ter­net con­nec­tion. At the oth­er end, in New York, there would be the 3D dis­play us­ing our la­ser sys­tem. Eve­ry­thing is fully au­to­mat­ed and con­trolled by com­put­er. As the im­age sig­nals are trans­mit­ted, the la­sers in­scribe them in­to the screen and rend­er them in­to a three-di­men­sion­al pro­jec­tion of me speak­ing.”

More­o­ver, he added, “as you move your head left and right or up and down, you see dif­fer­ent per­spec­tives. This makes for a very life-like im­age.”

The work is a re­sult of a col­la­bora­t­ion be­tween the university and Nitto Denko Tech­ni­cal, a com­pa­ny in Ocean­side, Ca­lif. The sys­tem is a ma­jor ad­vance over com­put­er-gen­er­at­ed holo­grams, re­search­ers said, which place high de­mands on com­put­ing pow­er and take too long to be gen­er­at­ed to be prac­ti­cal.

Cur­rent­ly, the sys­tem can pre­s­ent in one col­or on­ly, but Peygham­bar­ian and his team say they have ex­pe­ri­men­tally dem­on­strat­ed mul­ti­-col­or 3D dis­play de­vices ca­pa­ble of writ­ing im­ages at a faster re­fresh rate, ap­proach­ing the smooth tran­si­tions of im­ages on a TV screen.


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Remember the Star Wars scene in which R2D2 projects a three-dimensional image of a troubled Princess Leia delivering a call for help to Luke Skywalker and his allies? Scientists now claim that this science-fiction concept is close to becoming reality, thanks to a breakthrough in 3D holographic imaging technology developed at the University of Arizona. A research team led by optical scientist Nasser Peyghambarian developed a new device that allows the projection of a three-dimensional, moving image without the need for special eyewear such as 3D glasses or other auxiliary devices. The technology is likely to take applications ranging from telemedicine, advertising, updatable 3D maps and entertainment to a new level, the developers predict. The journal Nature chose the technology to feature on the cover of its Nov. 4 issue. “At the heart of the system is a screen made from a novel photorefractive material, capable of refreshing holograms every two seconds, making it the first to achieve a speed that can be described as quasi-real-time,” said Pierre-Alexandre Blanche of the university, lead author of the Nature paper. The prototype device uses a 10-inch screen, but Peyghambarian’s group is already testing a version with a 17-inch screen. The image is recorded using an array of regular cameras, each of which views the object from a different perspective. That information is then encoded onto a fast-pulsed laser beam, which interferes with another beam that serves as a reference. The resulting interference pattern is written into the photorefractive polymer, or a material that can have varying light-bending properly depending on the light hitting it. This polymer creates and stores the image. Each laser pulse records an individual “hogel” in the polymer. A hogel, short for holographic pixel, is the three-dimensional version of a pixel, the basic units that make up the picture. The hologram fades away by natural dark decay after a couple of minutes or seconds depending on experimental parameters. Or it can be erased by recording a new 3D image, creating a new diffraction structure and deleting the old pattern. Peyghambarian explained: “Let’s say I want to give a presentation in New York. All I need is an array of cameras here in my Tucson office and a fast Internet connection. At the other end, in New York, there would be the 3D display using our laser system. Everything is fully automated and controlled by computer. As the image signals are transmitted, the lasers inscribe them into the screen and render them into a three-dimensional projection of me speaking.” Moreover, he added, “as you move your head left and right or up and down, you see different perspectives. This makes for a very life-like image.” The work is a result of a collaboration between the UA and Nitto Denko Technical, a company in Oceanside, Calif. The system is a major advance over computer-generated holograms, researchers said, which place high demands on computing power and take too long to be generated to be practical for any real-time applications. Currently, the telepresence system can present in one color only, but Peyghambarian and his team say they have already experimentally demonstrated multi-color 3D display devices capable of writing images at a faster refresh rate, approaching the smooth transitions of images on a TV screen.