Activator
Activators are puzzle elements that accept laser light of a specific color and then activate other puzzle elements within a given radius without the need for direct connections. Specifically, they cause nearby gates to open and cause other nearby activators to activate.
Like receivers, each activator accepts only light of a specific color. However, an active activator will activate any nearby activator regardless of the secondary activator's color.
Puzzles
For a list of puzzles that contain activators, see Category:Puzzles with Activators.