Lean one way and you watch hordes of men in sandals and tunics race across a plain. Lean the other way, and you "can see up Brad Pitt's skirt", jokes Helen Maguire, as he leaps sideways in full Troy costume, seemingly right before you.

If the last hologram you looked at was something that came as a prize in a Christmas cracker, Maguire has something for you.

The director of Reverse Perspective, an Irish company representing the work of London holographic firm Colour Holographics, Maguire thinks that holograms are the perfect advertising vehicle for a population indifferent to television ads and seeking something with more oomph.

"People are so bombarded with information these days. They can screen out TV ads," she says. With nearly 80 per cent of sales accounted for by impulse purchases, Maguire says: "Point-of-sale campaigns are the most effective approach. Holograms are unique and quite magical."

Maguire, whose company is based in the Digital Hub in Dublin, says interest so far is keen in what she calls "hybrid holography" or "interactive colour holographics" - in other words, large, poster-sized holograms that marry 35mm film footage, computer graphics and holography.

The result is a gigantic hologram that contains enough 35mm film frames to show real action, and such detailed 3D effects that a glass being filled by a steadily pouring bottle of Jameson whiskey seems to hover in mid-air, a tantalisingly short grasp away.

Now, advertisers as varied as Nike, Sony, Ericsson and Gossard are fans of the technique, with the Nike advertisement, showing life-sized French footballers kicking a ball, proving a show-stopper for crowds on boulevards in Paris.

"Nike said it was the best point-of-sale campaign they've done," says Maguire.

So many people stopped on Oxford Street to sway back and forth and watch a giant holographic camera phone flip over and open, that the police had to be called in to move the crowds along, she says.

How did Maguire end up flogging holograms?

"I've loved them since I was a child," she says.

While working in the advertising industry in London, she came across the work of Colour Holographics and says she somehow wangled what she considers a dream job, selling the virtues of their large sheets of hologram-covered tri-acetate film to corporate clients.

Colour Holographics is the only company in the world making the giant holograms for this purpose after the company's two founders, hologram fan Michael Medora, and film-maker Nigel Robiette, accidentally stumbled on the technique that allows the manufacture of large-scale, long-lasting images.

"They joined forces seven years ago and literally came up with this in their garage," says Maguire.

The secret lies in a stable, silver halide crystalline emulsion for locking in the image.

They were experimenting and found a blend that was both stable and long-lasting - a feat that is "nearly impossible", she says.

A master hologram is made by coating a piece of glass or tri-acetate film with the emulsion, which reacts to laser light.

A typical three-dimensional hologram is made up of 80 separate frames of 35mm film, which gives three seconds of motion. Computer-generated animation, a still image, or a specially-filmed holographic shoot can also be used.

To create the hologram, the laser beam is split in two, with one beam going to the film or animation files and ricocheting back to join the other beam.

"The interference pattern as they rejoin goes to the plate," says Maguire. The pattern creates the hologram.

"If you smash a hologram, every part of the hologram is in the fragments," she adds, clearly delighted at the idea.

A special holographic printing press can duplicate the master hologram to tri-acetate, which can either be mounted on a plexiglass plate - lighter than glass and less fragile - or suspended from a wire and lit from above.

"You can see through them, which is a positive if you want to show off items set around them, such as mobile phones," says Maguire.

They can also be free-standing, or in a frame surrounded by "branding" - a corporate name and logo or products.

New techniques have allowed a combination of computer graphic imagery and holography to produce deep-perspective 3D images that seem to project a foot or two out towards the viewer - an effect that is startling and compelling.

People actually move backwards to avoid "hitting" the generated image, says Maguire, or reach toward it to touch what turns out to be empty air.

Film studios were quick to see the advantage of a product that could catch an audience's attention in a theatre foyer - an audience that might wait for film trailers to end before bothering to take their seats.

So far, holographic displays have been used to advertise films like Troy, Lord of the Rings - among the first commercial holograms, she adds "they are beautiful works of art" - Harry Potter, AI, Oceans Eleven, The Matrix and Scooby Doo.

Other clients include Guinness, Cadbury Trebor Bassett, Sainsburys, Budweiser, Thomas Cook and Pirelli. Maguire is talking to several potential Irish clients as well, ranging from bars and clubs to corporations.

A special passion at the moment for Maguire is organising the world's first holographic art display for an Irish show, which will include work by over a dozen artists, all with an Irish connection.

Called The Cathedral of Life, Maguire hopes to interest companies in brand sponsorship for the show, and would love "a crazy philanthropic millionaire" to donate the €100,000 to €200,000 that would kickstart the exhibit.

"I'm passionate about holography. I think the medium has this special quality and it's begging for creative exposure," she says. "It's got loads of power as an advertising medium, but has loads of other applications."

Don't get her started on the other realms in which holography might figure.

Research has suggested our brains may store information holographically, she says with enthusiasm, arranging it in a non-linear, multidimensional fashion. Seen one way, holograms might actually be our normal mode of perception.

Seen another, they are just plain fun - and not a bad way to give Brad a good once-over.