Your two eyes each see a slightly different view of the apple. These different views tell you about the apple's depth -its form and where it sits in relation to other objects. But a laser shines light in a thin, intense beam that's just one colour. That means laser light waves are uniform and in step. Spread by lenses and bounced off a mirror, the object beam hits the apple.
Light waves reflect from the apple towards a photographic film.
The reference beam heads straight to the film without hitting the apple. The two sets of waves meet and create a new wave pattern that hits the film and exposes it. But all holograms are created with lasers -and new waves. Like many great ideas, Gabor's theory about light waves was ahead of its time. But for more than a decade, Gabor had only half the words.