1: You mean the page turning laser pointer, applicable to Windows 7 or 8 system.
2: Not frequency, but power. Indicates that the power is 5mw, and the usually written power is less than a certain nominal power.
Why does the laser pointer beam illuminate the sky with a certain length, and there is a beam nearby but not far away? Why does the farther the beam shines, the larger the spot
The large spots in the distance are due to the laser's divergence angle. Although it looks condensed, it is slanted. The farther the distance, the greater the divergence and the larger the spot.
The laser beam seems to disappear from a distance, because 1 means that the range of the laser itself is limited. The farther the distance, the weaker the brightness. In theory, it can be seen that the light spot disappears when it reaches a certain node.
It is difficult to see and judge the node with the naked eye. Therefore, the light beam disappears where the human eye can see. If you use a telescope, if the power of the green laser pointer itself is high and the beam range is beyond the visible distance of the human eye, you can use the telescope to view the further beam.
Will playing with a laser pointer cause blindness?
Neither high-power lasers nor low-power lasers can illuminate the eyes. Occasionally, I saw children hurt their eyes by laser in the online news. Without exception, they looked at the laser for a moment. Understand the potential hazards of the optical laser pointer, don't do it, and use it correctly, there will be no problems. This is a case of misuse.