Uranium Glass

[Alaskan]

Guys, are there anyone members who can help me understand how uranium glass glows green when UV light hits it? I've been searching the net and found some information, but have not hit upon the right search terms to find some good info regarding ground and excited states which cause the fluorescence, the width of its emission in nm and whether the light might be something we can collimate into a tight beam.

Anyone look into this before? I've found some reference that the light cannot be collimated by flashing a uranium glass rod with UV as we do with YAG rods using IR because the output is broadband light, but another web page stated it is 550 nm, not sure what the story is.

Chris

 

[paul1598419]

Almost everything that fluoresces is broad band if looked at with a spectrometer, so using it as a lasing medium seems unlikely to me. I haven't done a search, but you might have better luck using search terms like fluorescent materials, black light fluorescence, and such.


Edit: Just for you, Chris, I took out a uranium marble and a 405nm laser (defocused) and took a spectrometer reading of the output. There is a spike at 405nm and a large haystack waveform from about 480nm to 600nm. The two peaks on the haystack are around 512nm and 535nm. If you need to see it let me know and I'll post a picture of it for you.

 

[Alaskan]

Wow, appreciate your doing that for me Paul. A ND YAG produces a few lines, one strong at 1064, but this material a hay stack of fairly broad spectrum stuff, but I bet if you pumped it hard enough and used the right mirrors you could get a collmated beam, perhaps weak?

 

[paul1598419]

IDK, Chris, There weren't any transition lines like you would see from Nd:YAG. Just a huge haystack from ~480nm all the way to ~600nm. How you would pump that to get any coherent light is beyond my understanding of optical pumping. The only line was the one from the 405nm laser I used to get it to fluoresce.

 

[Alaskan]

OK, not enough power in a peak to gather enough of it together in phase with an HR and OC mirror but, I bet you could get a few milliwatts. IDK, some guys buy 1 mw output lasers, I bet I could get that if a narrow enough filter were put in a cavity, or narrow band mirror, some of that green has got to be coincidentally in phase if you build a cavity. The reason I ask is I found some nice 6 mm Corning 3320 uranium glass rods. I thought they would be cool to use with some small UV laser diodes to light up the rod as a decretive addition to the side of a laser pointer to make it glow a green color, but then I wondered if any amount of collimated green could be gotten in a cavity. I am sure if this were efficient enough it would have been done, nowhere can I find reference on the net to anyone having done so... that usually means you can't.. but then I'm also not finding much about the subject either, so maybe a small amount can be had. Maybe I'm way off base, that the kind of light we get out of this glass isn't anything like what we get from a ND YAG or ruby rod etc, just a broadband mish mash of green without a lot of in phase power at any one WL to work with, as your graph appears to indicate. I'd be happy to see you post your results here, or PM me, please do.

Thanks.

 

[paul1598419]

I'll have to print out the spectrum from my laptop I use only for this purpose and scan it into my laptop I use for everything else, but I will post a spectrum for you as soon as I can get it done. I haven't yet figured out a better way to do it. I'm sure there must be. I'd rather take a screen shot of what I am seeing when I take a spectrum, but I don't think that is possible.

 

[paul1598419]

Sorry for the double post, but I wanted you to get this right away.

 

[Alaskan]

Great, nice to see that beautiful graph. I see what you mean now. Maybe one day I will try to get some HR and OC mirrors for green with HR/HR for 405 nm, side pump it and see if I can get much green collimated light out, if any.

 

[paul1598419]

If you can do it, I'm sure it will be something to write a paper about. I would love to see something like that. I gotta say that finally having this spectrometer after wanting one for so long is really great and gives me the tools to do things I never thought I'd be able to do.

 

[Alaskan]

Nice, the more I want to do in this hobby (I corrected it, but accidentally typed jobby, which it is) the more I see the need for one.

 

[paul1598419]

Yeah, and if you need to, you probably will be able to sell it and get much of your money back. But, don't cheap out if you can help it.

 

[CurtisOliver]

Yep, Paul nailed it.

Nice spectrograph BTW. :beer:

 

[paul1598419]

Thank you, Curtis.

 

[diachi]

Thanks for posting the graph Paul!

Not only do you need to take emission spectra/transitions etc and pump absorption into account, you need to look at the physical properties of the material. Will it withstand the high intensity pump light? The heat produced?

 

[Alaskan]

Maybe not, I've had the same concerns.

 

[Laserbuilder]

Unfortunately, I will possibly disappoint everyone in this thread who hopes to get some laser light from the uranium glass. As far as I know from my old dusty books, _there_were_ solid state lasers _existing_ that utilized Uranium U3+ ions as an active medium. These ions were put into CaF2 or CaWO4 crystal matrix (like YAG for Nd ions). Actually this was the very_first laser that worked through the four level pattern. It could work only when cooled down with liquid nitrogen and does not work under normal room temperature. It had a very weak 2.5 um lasing line which is absolutely not interesting. I haven't seen any reports about any other lasing lines. This type of laser was not used in any practical applications, it was only an object of scientific research in the 60's, after ruby laser invention. When other lasing mediums were discovered, the "Uranium laser" was quickly forgotten...