Re: Is there a way to alter the color of a laser after it left laser cavity?

Erik,

The answer to your first question, "Is there any way to change the frequency and ultimatly the color of a red laser after it has left the laser cavity" is yes. But because you are using an ordinary red laser pointer, I think you would find that doing this would be far too costly to be worthwhile. Let me describe to you two ways I know of changing the wavelength of a laser, post-cavity...

The first example I know of is actually down in my laser laboratory. We have an Argon laser which exits its cavity and is then angled through a special Beta-Barium Borate (BBO) crystal. BBO crystals are nonlinear optically, so the result is that the Argon wavelength is halved from 488 nm to 244 nm which is in the ultraviolet. This type of laser is sometimes referred to as a "frequency doubling" laser. Unfortunately, even the tiny crystal in my laser (it's about 3 mm x 5mm) is many thousands of dollars. Probably not what you're looking for?

The second example is something I only recently learned about from NASA. NASA has developed a multiwavelength laser which only requires a single laser cavity. The way this works involves a special laser cavity which has its output modulated through the rate at which the laser material is pumped. The beauty of this method is that the wavelengths are switched electronically, rather than mechanically, so separate cavities are not necessary. But unfortunately, I don't know the details of the special cavity that is needed to do this (you'd have to ask NASA!) and I'm sure it would still involve you taking apart your laser pointer.

I hope that helps!
Amber