How did lasers help create the first three-dimensional holograms?

Lasers were essential to the development of holography because they provide both high light intensity and a high degree of coherence, which conventional light sources lacked.12

To create a three-dimensional hologram, a laser beam is split into two identical halves. One half, the object beam, illuminates the subject, while the other half serves as a reference beam. These beams are recombined on a photographic plate, where they interfere with each other to record not only the intensity of the light but also its phase.432

This phase information is critical, as it captures the exact depths and heights of the object's contours. When the resulting hologram is later illuminated by a laser, the recorded interference pattern diffracts the light to reconstruct the original wave front, creating a three-dimensional image. While Dennis Gabor conceived the theory in 1947, the technology only became commercially feasible following the demonstration of the laser in 1960.3241