Solution:

Our eyes?ensitivity peaks at around the wavelength of green light. So, you could have a red and green pointer, both with a power rating of 1mW, but the green one would look about 30 times as bright. Green light also scatters more in the atmosphere than red light does, which is why amateur astronomers often use green laser pens to point to features like planets or constellations in the night sky.
The eyes of pilots in an illuminated nighttime cockpit are most sensitive to greenish-yellow light (of wavelength around 500?0 nanometers, peaking at 555 nm). A blue or red laser will appear much dimmer?nd thus less distracting?han a green or yellow laser of equal power. For example, a 10-watt continuous-wave yttrium aluminium garnet laser at 532 nanometers (green) can appear brighter to the eye than an 18-watt continuous-wave argon-ion laser that outputs 10 watts of 514 nm (green-blue) light plus 8 watts of 488 nm (blue) light.