It is very important that the laser light is in a good visible color spectrum as well as the diodes have a very low divergence. The beam diametre at aperture is normally not relevant, especially over longer distances.
The laser beam should have a round beam shape in all colors, so all colors match 100% and give a perfect white.
The scan speed should fit the requirement (the more complex the application, the faster scanners are needed)
The laser output power should fit the application (use our Laser4U tool to select the right laser)
A professional laser display system should be computer controllable (and should be controlled by computer)