First of all, the propagation of light does not need medium, and the farthest laser flashlight can illuminate it, some of which are 5000 meters or even 50000 meters. In that case, the children bought it to illuminate the flying plane. At present, the real and maximum power green laser flashlights, some reach 700mw-800mw, and some manufacturers reach 1000mw. Of course, the price is around three or five thousand, and the price of 1000mw is higher.
The green light range of 700mw is as far as 100mw with naked eyes, because no matter how far the laser is irradiated, your field of vision is limited.
If you look through a telescope, if the air quality is good, it should be in the range of 3000-5000 meters.
If the air is bad, the range will be closer.
The reason is simple: the air is bad and the sun can't be seen clearly in foggy days.