Science
How does a hologram work?
A hologram works by recording not just the brightness of light from an object but also the way its light waves interfere. Shining laser light back through that recorded pattern recreates the object's light field, so the image looks fully three-dimensional.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how a hologram works.
Step by step
- 1A laser beam is split into two: one lights the object, the other is a reference beam.
- 2Where the two beams meet they interfere, and that pattern is recorded on film or a plate.
- 3The pattern stores the light's phase, not just its intensity — the key to 3D.
- 4Shining light back through it reconstructs the original waves, so the scene appears to have depth.
- 5Shift your viewpoint and you can see slightly around the object, just like a real one.
Frequently asked questions
- How is a hologram different from a normal photo?
- A photo records only brightness and color from one viewpoint; a hologram also records the light's phase, so it reproduces depth and parallax.
- Are the floating 'holograms' in shows real holograms?
- Usually no. Most stage 'holograms' are clever reflections (like the Pepper's ghost trick), not true interference-based holograms.
- Why do holograms need lasers?
- Lasers produce coherent light — waves marching in step — which is required to create the stable interference pattern a hologram records.