French presidential candidate Jean-Luc Melenchon is pulling out all the stops in the final days of the campaign season, beaming a holographic image of his far-left message to six cities across the country. There's only one problem with Melenchon's incredible technological feat: It isn't actually a hologram.
Melenchon used the same technique that brought Tupac back to life at Coachella in 2012 called "Pepper's Ghost". It's a trick that has been used since the 19th century by magicians and amusement parks alike. The trick essentially employs a special piece of glass that is both transparent and reflective, meaning that it's able to make a two-dimensional image appear to be floating in air when light is bounced off the glass at the right angles.
In the modern era, this type of image can be manipulated with powerful computers and projectors with extremely precise accuracy, making it appear that someone is standing in the room when they, in fact, are not. Although it's a neat trick to see in person — it isn't actually a hologram.
This isn't the same as a hologram because, by definition, a hologram is a three-dimensional image "reproduced from a pattern of interference produced by a split coherent beam of radiation (as a laser)". In essence, this means that a true hologram is an 3D image that can be seen without the aid of glasses or other intermediate optics like the wall of glass used in Melenchon's setup.
The modern definition of a hologram emerged in the early 1960s shortly after the advent of laser technology, when Soviet scientist Yuri Denisyuk and US scientists Emmett Leith and Juris Upatnieks developed primitive 3D hologram systems in tandem. According to Nature, Leith and Upatnieks "used a laser and an off-axis configuration" while Denisyuk used "white light as source" to essentially obtain the same results.
Both teams were among the first to use lasers to display 3D images of static objects without requiring any special glasses or other optics. Although early systems required high-powered expensive speciality lasers, newer systems are now taking advantage of mass-produced diode lasers like the ones used in DVD recorders. This technology isn't widely used right now, though new "volumetric displays" like the one we checked out at Looking Glass Factory could become more popular in the near future.
By contrast, if you were to stand really close to the Melenchon hologram setup you'd see that the image is clearly two-dimensional. It's a very long way from Princess Leia's hologram message in Star Wars: A New Hope.
Melenchon, 65, is using the gimmick to help himself stand out in a highly contentious French election that begins on Sunday. Melenchon is pitted against conservative Francois Fillon, far-right candidate Marine Le Pen, and moderate Emmanuel Macron. The polls still show that Macron is the favourite to win, but Melenchon is surging according to reports from the Telegraph and Reuters. We imagine this is in part to appealing shtick like his fancy, albeit fake, "hologram". Let's see if voters still find it impressive once they know they have been duped by a 19th century magician's trick.