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The Photonics Spotlight

Beams of Laser Pointers: Visible in Air?

Dr. Rüdiger Paschotta

Ref.: encyclopedia articles on laser pointers, laser beams; Wikipedia article on Luminosity function

I have two laser pointers: a small red one, and a larger green one (see the figure).

laser pointer

Figure 1: A green-emitting laser pointer, containing a tiny diode-pumped frequency-doubled solid-state laser.

When I take the green laser and shoot into the night sky, I very clearly see the beam in the air over a large distance. When I do that with the red laser, however, hardly anything is seen.

There are three reasons for that remarkable difference:

In combination, one should expect that the visible brightness of the scattered light from the green laser is much larger than for red light. And this perfectly fits to the experimental experience!

This article is a posting of the Photonics Spotlight, authored by Dr. Rüdiger Paschotta. You may link to this page and cite it, because its location is permanent. See also the Encyclopedia of Laser Physics and Technology.

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