Uploaded December 2024 | Updated September 2026, 1 hour ago

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Have you ever wondered how holiday laser light displays work? These laser holiday displays project hundreds of laser beams, but how can so many lasers fit into such a small package? You might be surprised to know these laser displays only need a single laser. They use something called diffraction gratings to diffract the one beam into many.

Diffraction is the property of waves that allows the bending around corners. It’s a result of the waves getting bent from obstacles and edges they encounter. This can be seen when placing small obstacles like a strand of hair in the beam of a laser. The diffracted waves at the obstruction’s edges interference, creating complicated patterns of light. When small line structures are placed side by side, they form a diffraction grating and can generate multiple beams even if the structures themselves are transparent like glass or plastic.

By stacking multiple diffraction gratings in a row in different orientations, a dynamic pattern of beams is created.