What is a hologram?
A hologram is a 2D surface that can scatter light in such a way as to make 3D shapes outside the plane of the surface when they are suitably illuminated. In technical terms, a hologram reconstructs an image using the physical principles of diffraction.
What is diffraction?
The most familiar optical phenomena are reflection (light goes backwards, in a mirror) or refraction (light it bent, in water or a lens). Diffraction occurs when light hits and scatters off features that are about the same size or even smaller than the light (around 500 nanometres). Diffraction is a powerful optical effect that can replicate both reflection (Bragg diffraction) and refraction (Fresnel diffraction), which lead to two types of hologram: reflection holograms and transmission holograms.
What kinds of holograms are there?
There are two main types of holograms: Reflection holograms (Bragg diffraction) only need to be illuminated by a single bright light source such as a halogen spotlight. The light source is placed in front of the hologram that is reflected back to reconstruct the 3D shape. Secondly, transmission holograms (Fresnel diffraction) need to be illuminated by a laser that shines through the hologram, a bit like a lens, to reconstruct the 3D shape.
What is a digital hologram?
A digital hologram is a computer-generated hologram derived from a 3D graphics model that is printed using a holoprinter device. The holoprinter prints the 3D image as a series of small dots or holopixels. Digital holograms are reflection holograms that are full-colour and only require illumination by a simple spotlight.
What is a holoprinter?
A holoprinter is a holographic printing device that makes digital holograms. It uses red, green and blue lasers to write a series of dots or holopixels/hogels across a holographic medium. Each dot is encoded with a unique view of the scene from it's own perspective. The holographic medium is usually a polymer film that is subsequently laminated on to a hard plastic backing for rigidity.
Can you make a "hologram" of my favourite pop star, politician?
Nope, I'm afraid not. The famous Tupac reincarnation at the Coachella 2012 festival was not, in fact, a hologram. It's an age-old optical illusion known as Pepper's Ghost which basically reflects a 2D projection off a thin plastic film. This gives an illusion of a floating image behind the film. It is not a 3D image but if you are in a concert and located more than 10m away from the image then you basically can't tell the difference. The creaters, Digital Domain, have since gone bust. The upside is that this has increased awareness of real holographic technology and its potential for the future.
How large can you make a digital hologram?
The largest standard size is A1 (850x600mm) but larger custom sizes are possible. Depending on the holoprinter, we can produce holograms up to 1.0x1.5 metres. It is also possible to tile several holograms together. These would require a large bright light for illumination, such as a stage spotlight.
Can a hologram be viewed with a full 360 degree walkaround?
Yes it can! This is an option (horizontal configuration) which is popular with all kinds of designs and 3D models including machines, automotive, architectural plans and other layouts. Please contact us for more info.