How can full-colour holograms be made with red green and blue lasers?

Full-colour holograms are achieved by leveraging the principles of holography to record and reconstruct the optical field of an object using three primary colours.

Because a hologram records both the intensity and phase of light, it is possible to superimpose three separate holograms onto a single recording plate. To create a full-colour image, three distinct holograms are recorded simultaneously—one each using red, green, and blue laser light.12

Even though the resulting hologram plate itself remains black-and-white, it contains the encoded information for all three colours. When the hologram is later illuminated with the same three laser colours used during the recording process, the interference patterns act as a diffraction grating. This reconstructs the original light waves, causing the three images to combine and produce a three-dimensional representation of the object in its natural, full-colour spectrum.1