'Peppers Ghost' was first demonstrated in 1862 (although it is first mentioned during the Tudor era, in 1558), and used a large sheet of glass at an angle between the stage and the audience, with a hidden performer playing 'The ghost'. When light was shone onto the hidden performer they would be reflected onto the glass, where they would appear as a transparent figure against the stage.

Our holoprism works on a similar, though much smaller principle. The object, in this case a tankard, is reflected off the holoprism at an angle, while allowing the background to be seen through it, creating a ghostly effect.