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Optics

Tridimensional image

3D TV prototype does away with special glasses

JOSÉ LUNAZZI / UNICAMPTridimensional (3D) television technology is one of the major attractions of the World Cup in South Africa for those who were unable to travel and watch the matches in the South African stadiums. Twenty-five of the Cup’s matches – including the three in which Brazil played in the first stage of the competition – were transmitted in 3D, the same technology that won over millions of spectators around the world with the movie Avatar in the cinemas. As in this superproduction directed by James Cameron, the spectator must use special glasses to see the matches with tridimensional images, which create the feeling of depth and relief. However, experts believe that in the future 3D technology will no longer be hostage to this bothersome device that generates discomfort, visual tiredness and headaches for some people – not to speak of the hygiene issue involved in sharing glasses with other people in the cinema. In many countries, there is research under way to create tridimensional TV without special glasses. In Brazil, this technology is gaining shape in the studies of researchers from the State University of Campinas (Unicamp). Led by professor Jose Joaquin Lunazzi, they have developed several prototypes of a 3D TV set that produces holographic images. Holographs are tridimensional images formed by a film, called a hologram, on which laser beams cast upon a person or object are recorded. Lasers or white light are used in the reproduction.

“Our technology, which we have called Holo TV, plans to get rid of the glasses and offer full visual comfort. It bears no resemblance to any system in the world, even in terms of prototypes”, explains Lunazzi. “It consists of images that are projected onto almost transparent screens, in which the absence of the vision of the support generates a ghost-like figure that is similar to a holographic image. The filmed scene can be seen without glasses with the same smoothness and naturalness of a hologram”, he says. One of Brazil’s pioneers in the study of holography, Lunazzi began his research into the creation of a 3D TV set back in 1984. Ten years later he obtained FAPESP support and acquired a movie camera, a projector, holographic film, a laser device and photographic lenses. With these tools, he set up a system for generating and reproducing holographic images. In 1988, he presented the first prototype of his holographic 3D TV set.

Off the screen
Just like the devices that offer traditional 3D technology and that require special glasses, holographic 3D TVs also project images beyond the screen, but they still need adjustments before they can be launched. Research centers such the Massachusetts Institute of Technology (MIT), high technology enterprises such as Holografika (a Hungarian company) and the large manufacturers of electronic devices are all working on the construction of commercial models. Last year, Philips, the Dutch firm, carried out trials with a 3D TV set that did away with the glasses, but that required viewer to sit in a fixed position in front of the set to avoid seeing jumbled images. Because of this limitation, development was suspended. The device used a technology known as autostereoscopy in which the lenses of the set’s screen create multiple regions in alternation in front of the screen itself. This very same technology was used by Samsung, the Korean manufacturer, in a prototype shown to the public in January of this year at the Consumer Electronics Show (CES) 2010, the world’s largest electronic fair, held in Las Vegas, United States. More recently (last April), a Japanese firm, VMJ, presented at a Tokyo technology fair a 65-inch TV that showed 3D productions without requiring glasses. This prototype has a sort of film full of slits over the screen. This causes the eye to see a different image, creating the feeling of depth. The technology was successful, but it must still overcome obstacles in order to become commercial, including lowering production costs and eliminating the need for the viewer to sit in certain positions relative to the screen in order to see the image properly – the same barrier that the Philips models encountered.

078-079_Info_TV3d_INGLESThe technology created at Unicamp, according to Lunazzi, does not present such difficulty. “The person can change positions as much as he or she wants without losing the 3D illusion”, he guarantees. This is due to the discovery of an optical principle called codification-decodification of depth by light diffraction. “I developed this principle when I returned from a holography exhibition in Germany in 1984 and it was divulged in an article in the journal Optical Engineering in 1990. Ever since, nobody has applied it. Our research is advancing, but to date we have only managed to create monochromatic 3D images, with no color or brightness”. Early last year, along with three colleagues in his group, Lunazzi wrote a new article in the journal Optics Letters, describing the system that they have created, which has a 30 cm by 60 cm screen. One important detail of the technology is that the screen, which is transparent and made out of photographic film with high-resolution silver salts, is lit obliquely, sideways – unlike the conventional screens, which are lit from behind or in front. This is a fundamental aspect, according to the researcher, for the process to occur and the viewer to enjoy freedom of movement without losing the images 3D illusion.

Lunazzi has already presented his technology in congresses in Japan, China, the United States, South Korea and European countries. “Holo TV has an experimental, prototypical character. It is useful to encourage research around the world and to show that we can engage in cutting-edge research in Brazil”. In its current stage, it could be used in the large promotional stands of companies at fairs. In 2008, Samsung researchers visited Lunazzi’s laboratory at Unicamp’s Physics Institute, to become acquainted with the new holographic technique by double diffraction of white light without the intermediation of the lens, used in Holo TV. However, no agreement was signed. The researcher believes that the commercial viability of his tridimensional TV will require partnership with a major global producer of electrical and electronic goods interested in investing in this research.

The project
Generating tridimensional figures and images (nº 93/02501-1); Type Regular Research Awards; Coordinator Jose Joaquin Lunazzi – Unicamp; Investment R$ 23,874. 65 (FAPESP)

Scientific article
LUNAZZI, J.J. et al. Holo-television system with a single plane. Optics Letters. v. 34, p. 533-35 (2009).

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