lasers or spotlights for colored "sky lights" (project)
Mayor approved a project where we will shine few colored beams from a tower across our small town, we also got permission from the civil and military aviation bodies.
Right now the light source is an array of high power red, green and blue laser diodes. They are not scanned, but static beams so beam diameter and distance between each other is not as big of a deal as they will diverge into each other anyway.
My question is, is lasers perhaps not the best technology for this after all? Should we be maybe using poweful spotlights with filters? In my experience they can't be focused enough as lasers to be noticeable after 10 km (which is the goal) and lose too much brightness from filters but I might be wrong.
What do you think?