- #1
elemental09
- 42
- 0
I was setting up a 2.0 mW, unpolarized 543 nm (green) He-Ne laser today when I discovered something odd. I was using an iris diaphragm (like these: http://www.thorlabs.com/NewGroupPage9.cfm?ObjectGroup_ID=206) to align the beam parallel to the laser table. I found that if I placed a white cardboard sheet behind the iris, whose aperture was slightly off the beam axis, and closed the iris just enough so that no green light was visible on the white cardboard, a faint purple/violet glow remained. I drew a crude diagram, see:
http://img560.imageshack.us/i/lasery.png/
Note that the shape of the purple/violet glow on the paper was not exactly as pictured. It seemed roughly parabolic, with the glow fading in intensity.
What's happening? I can't explain it.
http://img560.imageshack.us/i/lasery.png/
Note that the shape of the purple/violet glow on the paper was not exactly as pictured. It seemed roughly parabolic, with the glow fading in intensity.
What's happening? I can't explain it.