The laser pointer is the best and convenient size

The laser pointer is the best and convenient size and does not require hands-free operation.
Astronomy
Green laser is the only color, should consider the astronomy.The number of required power vary depending on the person you will use.As a general method, the more people you and strong laser energy.Usually a 15 MW 35 MW is sufficient.As pointed out by hand and a laser pointer is the ideal.For installation in a telescope, a laser with a hands-free medium size is the best.
Combustion
For the combustion of common, such as lighting a match, cutting electrical tape, broken balloons, 95 - 125 MW power is more than sufficient.If the money is not a problem, you want to smoke, burning clothes and melt the plastic, you will need at least 150 - 200 megawatts of electricity.
Color is not a problem, because of high power laser can only be green.
Pointing out the door
A beam is clearly visible, in direct sunlight in a long distance, at least 55 MW power is wise.For some applications, such as alignment, laser and an on / off switch and efficient radiator is ideal
Non-lethal deterrence
For maximum effect and influence, at least 200 megawatts of power would be the ideal.Higher power will make the laser to stop people faster and longer range.In the tactical environment, laser portability is a problem and smaller as Sparta series is ideal.