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As I said, I'm not interested in engraving, despite the original advertisement. DpSS sounds cool, but I have heard that if it's done improperly they can leak light in the driving frequency, which would mess up my fluorescence. I guess I could filter it to be sure. Anyway, I'm saving that idea...

Ah, yeah, that’s probably too shortwave anyway. Some things do visible-fluorescence there but I haven’t tested in that part of the spectrum.

Oh, it's not a problem, just shorter seems to be better from my LED experiments. For now, 405nm remains the plan. By the above conversation, the UV lasers are too fickle for my needs anyway, although I may test them out at some point. Huh, is dpss used at 405nm or shorter? I don't recall seeing...

True, although my tests with LEDs have shown that 365nm UV tends to work slightly better than 405nm. But my plan was to use 405nm. Remember, I stumbled on the above set by CHANCE. Yes, I do need a laser, because for one thing, lasers can excite fluorescence that can't be seen with LEDs, simply...

Hah, yeah "engraving" was a red herring. Fluorescence is the main point.

Please see my most recent post (we overlapped). I'm not using it for engraving.

Unfortunately, I probably do need the power. The application is laser-induced fluorescence photography on brick walls in the presence of streetlights (since the imaging has to be done late at night when people are out of the way). The laser will have a 30 degree Powell lens on it, which spreads...

I know (see username...) but I was looking for something more like 375nm. Someone put something like a 375nm on the board not long ago, but I couldn't recall what kind of diode it was.

Thanks, figures, it seemed too good to be true.

As seen on eBay (and I apologize if I have the wrong forum for posting this in, I'm still fairly new to the board here). I still can't post links, but here is the eBay item number: 324433789477 The title is, "1-W+ UV Handheld Laser Engraving Kit - GH04W10A2GC Diode - Extreme Ultra-Violet" by...

Thanks, this was very interesting.

You can buy a laser with a line lens? I'm not sure I'm imagining the situation you have in mind though -- could you post a diagram?

Even if you had made the hole while it is hot, it actually wouldn't matter -- if the hole is too big for a certain pressure and thickness, it WILL crack. You can actually calculate the radius where it will happen. It's not really a matter of how you make the hole, it's just that when a hole is...

Trying to incorporate an optical window in a piece of blown glass with no leaks and without having the whole thing just crack on you when you fill it with liquid is going to be a very tall order. I think the idea of polishing/grinding the glass to the necessary quality in a particular location...

Or shampoos.

Try putting olive oil on top of tonic water with a 405nm. Tonic water will be blue and olive oil is red I think.

I think quinine (tonic water) will fluoresce under 405nm?

Water's absorption spectrum looks like this in infrared: That's a logarithmic scale, and visible light isn't even on the graph, so you can imagine how low the absorption is in visible light compared to the 1500-1600nm range! The dotted line shows the transmission of the 980nm filter I used for...

So true! Here is what snow looks like between 1500-1600nm (taken with a camera with a germanium sensor, not silicon) in shortwave infrared: and 980nm (near infrared, taken on a silicon camera with blocking filter removed): and visible light (with iPhone):

Hi, welcome, I joined myself just day before yesterday. Don't look to me for great laser knowledge (it sounds like you know more than I do already) although I've got an excellent mechanical engineering background so if you ever have questions about fluid mechanics or thermodynamics, hit me up...