I took a trip down to the laser lab to get the scoop on my green laser pointer. The following video documents my journey:
The take-home message? Just because you can't see the infrared doesn't mean it isn't there. It can burn your eyes just as much as the green can. Just keep that in mind if you get your hands on a cheap green laser pointer.
For your reference, here is a chart of the electromagnetic spectrum, which shows where visible light is, and where infrared light is in relation to each other.
The three spots we saw in the video were the separated colors of light from my laser pointer. The left spot was green (532 nm), the faint middle spot was near infrared from the pump (808 nm), and the right spot was the infrared (1064 nm) that gets frequency doubled to green. Here is the picture in the video showing the steps taken to produce the green light:
In the video, I refer to an "infrared camera," but the tool I use is actually called an infrared viewer. The combination of the viewer with my camera, though, does imitate an infrared camera! So my verbal mistake wasn't too far off. Also, the video alludes to a nonlinear crystal that converts infrared light into green light. This is a fancy way of saying that the atoms in the crystal absorb reddish-colored light and emit green-colored light. This happens through a nonlinear process, and needs to happen because there are cheap materials that naturally can be used to make an infrared laser. Only recently has there been success with true-green emitting materials, as I report in my
3OH!3 post. I discussed a little about nonlinear processes in
Adding and Subtracting for those who want to learn more.
Take a look, and enjoy the cool things I demonstrate in the laser lab! And definitely ask me questions if you have any!
