Encyclopedia … combined with a great Buyer's Guide!

Sponsoring this encyclopedia:     and others

Beams of Laser Pointers: Visible in Air?

Posted on 2010-01-11 as a part of the Photonics Spotlight (available as e-mail newsletter!)

Permanent link: https://www.rp-photonics.com/spotlight_2010_01_11.html

Author: , RP Photonics Consulting GmbH

Abstract: It is explained why the beam from a green laser pointer is much better visible in air than for a red laser, even though the difference in output power is not that large. The main reason turns out to be the wavelength-dependent sensitivity of the human eye.

Dr. Rüdiger Paschotta

Ref.: encyclopedia articles on laser pointers, laser beams; article on luminosity functions

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 RP Photonics Encyclopedia.

Note that you can also receive the articles in the form of a newsletter or with an RSS feed.


If you like this article, share it with your friends and colleagues, e.g. via social media:

How do you rate this article?

Click here to send us your feedback!

Your general impression: don't know poor satisfactory good excellent
Technical quality: don't know poor satisfactory good excellent
Usefulness: don't know poor satisfactory good excellent
Readability: don't know poor satisfactory good excellent

Found any errors? Suggestions for improvements? Do you know a better web page on this topic?

Spam protection: (enter the value of 5 + 8 in this field!)

If you want a response, you may leave your e-mail address in the comments field, or directly send an e-mail.

If you enter any personal data, this implies that you agree with storing it; we will use it only for the purpose of improving our website and possibly giving you a response; see also our declaration of data privacy.

If you like our website, you may also want to get our newsletters!

If you like this article, share it with your friends and colleagues, e.g. via social media: