How does a beam splitter help create a hologram?

In holography, a beam splitter is essential for creating the interference pattern required to record a hologram. It functions by dividing a single coherent laser beam into two distinct parts.12

One part of the beam is directed toward the object, where it is reflected, scattered, and diffracted by the object's physical features before reaching a photographic plate. The second part, known as the reference beam, is directed onto the same photographic plate, often via a mirror.1

By splitting the beam, the system allows these two light waves to meet at the plate and interfere with each other. This interaction creates a complex pattern of interference fringes—a record of both the amplitude and phase of the light reflected from the object. This phase information is critical, as it enables the reconstruction of a three-dimensional image, which distinguishes holography from ordinary photography.134