What are holograms?
Holograms are photographic recordings of light fields, of objects (or moments) viewed from many different angles. Photographs are images of moments captured from one angle. If you have a bankcard or passport, it will likely have a holographic print, which appears to move as you do. The print ‘remembers’ what the object looked like from more than one angle.
Check out angkimuttaqien‘s video of a holographic projection viewed from different angles:
How are holograms made?
Holograms are made by shining a laser towards an object and recording the light that bounces off it. A semi-transparent mirror splits this laser on the way to the recording medium (usually film). One half of the beam hits the film without interacting with the object. The other half hits the object before then hitting the film. The beam is then re-assimilated and burnt permanently into the film. In essence, we see bankcard holograms move because we see two impressions of the same light imposed on top of each other.
Projecting the future
We can capture images, we can project images onto surfaces, and, someday, holograms and hologram equipment, like cameras, like projectors, will be all around us. For now, free-standing holograms are still a staple of science-fiction (e.g. Star Wars, Back to the Future Part II, Vanilla Sky). Hologram Viewers can bridge the gap between centuries old magicians’ stagecraft – see Pepper’s Ghost – and the still-to-be-realised, picture-perfect moving representations of moments. In the right conditions, presented side-by-side, in our galaxy, in a future not too far away, it will be impossible to tell the difference between projected holograms of objects and the objects themselves.
Camera unobscurer
All in all, this series is just a brief look into the camera obscura and the devices that stem from it. If you’ve been inspired by any of these articles, why not develop your interest further, and check out IWOOT’s range of cameras, projectors and hologram viewers.
