January 24 Through February 4—TUCSON, ARIZONA: Annual show
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 Post subject: First simple experiment with laser - rethinking
PostPosted: Fri Mar 05, 2010 3:12 pm 
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Location: Hohe Tauern N.P., Austria
We tried a few laser shots on a big treated opaque Saphirre from SL.

I am Sorry, no pix, because we found out it´s not that easy to observe anything - the surrounding light conditions are influencing too much.

The Laser beam comes out in the discotheque after about 20 meters undergroound coming from the amplifierroom via glassfibre.

Where the original beam comes out, we tried to hold the crystal into the beam (the one that isn´t supposed to hit anybody´s eyes) and tried to observe flourescence reflection on the saphirre.

We ran Red, green and cyan and I think I saw a white reflection when the cyan Laser was on the crystal. But, the lasers atre in the Disco and it is impossible to make a proper measurement when there are so many different light sources on. The light of the beam is also much too concentrated, as DR. Bill said, our eyes are to protect, and so we decided to stop and rethink.

We will try this: guiding the laser around via our mirror system so the beam runs ziczac through the hall and is about 50 meters from source. There the beam is about 2 or 3 cm diameter (due to our hazers and the mirrors)and point it into a darkened Room or Box where we can take pics....

What I also observed was that the crystal was getting feelably warmer after a few seconds in the beam. Seems like the included opaque crystal absorbed a part of the light and heated up.


Here the specifications from the Laser´s Manual Book:
(Take twice since we have two of them running parrallel)
and I take a few shots of the laser system later tonight so you see that monster in action...

LOBO Electronic gmbh/Germany
Laserleistung: 4 Watt
Prüfklasse BGV-C1

but the documentation of a certified technician says:
Medium: Argon - Krypton
Typ: Purelight
Watt: 5,5
Ampere: 40
Hersteller: Coherent
Betriebsweise: CW
Laserklasse: 4


The System is water - cooled and needs about 16 liters per minute when active.

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PostPosted: Sat Mar 06, 2010 2:02 am 
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Nikolaus, that is a healthy "white light" laser system. Argon provides the violet and cyan and green. The krypton is also heavy on the blue and green, but it can be tuned to provides the red component necessary for "white" light. Way more power than I want to deal with, but you are doing the things I would do if I had to deal with the beast... very, very long path length increases beam diameter and decreases intensity.

As both the krypton and argon ion lasers produce several lines, probably your system has filters in place to allow only a few. Namely, 488nm (cyan, as you mention), 514nm (green), and 647nm (red). If I was going to focus my attention (ahem, pardon the pun), I would concentrate on looking at what can be done with the green. That should light up any chromium (without iron) gemstone bright red. It will also light up spessartine a nice orange color (different from the body color... um, more spectral orange). The cyan will also light up a spess, but isn't so good for the chromium gems.

Sadly, here is the downside to using lasers to light up gems. I have found that the intense laser light in the blue and green range can easily light up fingerprint oil! Insofar as every gem I test can glow red when I use the green 314nm light... and my laser produces one-fifth the green light yours does. To discount this fluorescence takes spectroscopic evaluation, but roughly any small glow you see is likely due to the fact that you touched the gem. My poor students have gone to great lengths trying to remove body oils from gems, only to be able to cut the signal but not remove it. So... any gem you touched is likely to show a slight red glow because of the body oil contamination.

A quick finale... if you see white, it isn't fluorescence. Also, at the power your laser(s) are dumping on the poor hapless stones, if all they do is "get feebly warmer," then count yourself lucky. I literally vaporize microscopic things with my 488nm beam (you can watch them start to boil from the inside out, if your camera is fast enough) that operates at one-fifth your power... but then also, my laser is focused about 100x, whereas yours is de-focused about ten times.


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PostPosted: Sat Mar 06, 2010 3:17 pm 
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Location: Hohe Tauern N.P., Austria
Thank you very much for sharing your experiences with me. Lasers are a part of physics education, but as soon as it comes to real experiments, most institutions lack the equipment. This Laser here will be under my control til end of may and I hope to get some experiments documented. The only thing is my gem collection is not witrh me and I have to send the particular stones to Ischgl first.

And I have permanent Virus problems, everytime I visit GO I get attracked by a confickr.worm. Sometimes in 5 min intervals. So still no pix to post from the beast and it´s beams. :oops:

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