Question about TRUE white lasers

[Low-Q]

Hi,

I have almost all om my life wondered why it is impossible to make a TRUE white laser by using one single laser unit.

I have allways been told that lasers operates in one single wavelength only - end of story. But I still wonder why it is impossible to make a broad spectrum laser which is covering any wavelength between, say deep ren and purple blue.

I have looked at these TEA lasers which is using a spark in normal air pressure to make the laser. The spark is bright bluish white, but only one waveleght, 370nm, is coming out of the laser. Why??

Br.

Low-Q

 

[Cyparagon]

I have allways been told that lasers operates in one single wavelength only - end of story.

That's only true of direct injection lasers HeNe lasers, and perhaps a few more types. Most lasers emit a few wavelengths. White-light lasers are ion lasers with argon and krypton as lasing mediums. They give at least 4 wavelengths, and upwards of... 15?

The spark is bright bluish white, but only one wavelength, 370nm, is coming out of the laser.

The spark emits many different wavelengths, but only one is amplified by the cavity.

It's analogous to any gas laser. Try this experiment: Look at a bare HeNe tube through a diffraction grating. You'll see many different colors (even blue!), but the laser dot is only one color - the wavelength selected for amplification (by the coatings on the mirrors).

 

[artix]

jamilm9 has a picture of one in his sig

 

[Things]

Like what was said above, there is such thing as single-unit white lasers, but they are usually always gas lasers. Whitelight gas lasers cost an upward of >$7000 or so for a small unit.

There is also Free Electron Lasers (FEL), which can be tuned to any wavelength, but are wayyyyyyyyyyyyyyyyyyyyyyyy out of the price range of almost any laserist. They also dont tend to be very high power.

 

[Switch]

usually always

jamilm9 has a picture of one in his sig

In his avatar...but then again, he has a picture of his avatar in his sig.

 

[jamilm9]

here i am and yes its in my avatar and sig

 

[GooeyGus]

As cyparagon mentioned, argon/krypton ion lasers lase throughout the blue/green/red spectrum and can have a white output. This is your best bet for high power white light.

There is also a metal vapor laser which has 24 different lasing lines throughout the spectrum and lases white. I'm referring to the "Helium Selenium" laser. These can actually be made without too much hassle (Dont get me wrong, it is a TON of work, but it's not so complex that it's impossible for a dedicated laser hobbyist)