How does a hologram work? (in 1 minute)
1. Interference fringes record the direction of light that was scattered by an object.
2. When illuminated, the recorded interference fringes act as diffraction gratings, which reproduce the direction of the scattered light.
3. By exactly reproducing the light field (i.e. both intensity and direction) that was scattered by the object, it is as if we see the actual object.
