Note that if you are buying a laser projector -- for a disco, for example -- the same projector may be available with many different laser options:
The lowest cost version will have a single color beam, usually green or red.
If blue is available, it will be at a higher cost and/or lower output power. This is because it is more difficult to produce blue laser light.
There may be a mixed-color version that uses two lasers, green and red. By mixing these, orange and yellow can also become available.
A full-color version uses red, green and blue beams.
-- The least expensive full-color projector will have 7 colors produced by simply turning on or off each of the RGB beams. The colors are: red, yellow, green, cyan, blue, violet and white.
-- Top-of-the-line full-color projectors allow shades of the individual RGB beams, so that just about any color or intensity can be produced. Be careful that the colors are well-balanced.
Sometimes, the green overpowers the other two colors, so that the laser's "white" light is more greenish.
Laser powers and visibility
A laser beam is only visible if there is particulate matter in the air, such as dust, fog and smoke.
The power of a laser beam is measured in watts and milliwatts (1/1000 watt).
The minimum power needed for a laser light show in a dark, medium-sized room (like a hotel ballroom) is
about 500 milliwatts to 1 watt. Somewhere between 5 and 20 watts is typical for indoor use.
In large arenas and outdoors, 10 to 80 watts is common.
Wattage alone does not determine how visible the beam will be.
For example, a 1 watt green laser beam can appear as bright as a 3 watt red beam, since the eye sees green light better
than red or blue.
Therefore, when deciding how much laser power to use for your show, there are many factors the laser company will consider.
Audience safety: In many parts of the world, the audience is scanned with laser beams.
The beam power and divergence must be sufficient that the beam and scanned effects are visible, but that there is no eye hazard.
One solution is to have the beam be at full power when above the audience, but at a lower power when scanning the audience