The Really Big Dye

[planters]

Dan,

This used to be a joke, but it is remarkably accurate...now. I might not even need to make my own video. The concept of a frozen singlet state was one of the avenues I actually pursued for a while, but 4 nsec to 6 nsec isn't worth it. I also tried to use that refrigerated system to cool the dye to around 3C to take advantage of the unique property of water that completely eliminates thermal lensing. It works, but the efficiency is quite low; not worth it despite the incredible beam specs.

I have holes in numerous targets... and a few non-targets as well including one healed hole in my hand. That was sure stupid, but encouraging .

I am not going to continue to upgrade this system despite the ease of doing so. The optics will simply not permit it without going to really exotic coatings. That is just too expensive.

[Vidal Wolf]

Im very interested to see this video as well.
Your work is so amazing to look at.
My work looks like a dumpster fire compared to what you craft / create.

[krazer]

Also excited to see some of your results!
That's a shame about blowing out the coatings, optical damage is usually what limits the output energy even in the big government funded lasers. Even at the NIF they can't get above 20J/cm^2 (for their few-ns pulses) even though their amplifiers are good for something on the order of double that.

[danielbriggs]

Eric... you need some of these mirrors! (1m diameter, from a 1PW Laser (soon to be upgraded to 10PW)
They weigh 3.5 tonnes each.

[norty303]

Beam diameter looks crap on that Briggs, you'd never get it on the scanner mirrors

[Diachi]

Beam diameter looks crap on that Briggs, you'd never get it on the scanner mirrors

Maybe if you used some fairly large 3 phase motors for galvos.

Looking forward to seeing more on this!

[planters]

Eric... you need some of these mirrors!

It's a start. But, the problem that arises is that the laser becomes ever more efficient as the dye cell diameter is reduced (assuming you have a really good, highly reflective pump chamber). It is the intensity of the beam within the cavity that kills. Even with a low reflectivity output coupler the interactivity intensity is still very high. One method I might investigate, if the mood hits me, is to use two folding mirrors, operating at a grazing incidence to spread the beam in one dimension and reduce the intensity on the cavity mirrors. So far, it is these and not the AR coated windows within the system that keep getting burnt.

[kecked]

How about a one axis spread with cyl lens through the dye to increase surface area and reduce peak power in the media followed by a second optic on the way out to put the beam back the way it was. They do that in the national ignition lab solid state lasers.

[planters]

I'm not sure exactly what you mean, but I think you are suggesting a telescopic arrangement (in this case, one axis). Here is the problem. The smaller the dye cell diameter, for a given pump energy, the higher the conversion efficiency, the lower the thermal lensing and the lower the divergence. The media in the case of these flash lamp dyes is pretty immune to optical damage and probably won't saturate much below 10MW/cm^2. Photo bleaching (as in mode locking, occurs at yet, much higher powers and much, much shorter durations). At these intensities, the first surface that might be used to expand the beam to ease the load on mirrors, filters, gratings etc, gets burnt in a single shot. I can produce truly huge pulses...once. The next is divergent, asymmetrical and lower power due to the ruined optic. The best results are with MgF2 coatings and moderately high energies.

[kecked]

r

I think this was the drawing I saw. Different purpose but the objective was not the special filter but to spread the power over the optics. The only other way I see is medium flow to take the inverted away and offer a new fresh solution. Flowing dye I think is the term. https://www.osapublishing.org/as/abs...ri=as-30-3-362

I wonder if you could do it by using a compression wave in the cell to move the dye around. A standing wave from a transducer. If the spot size was small enough it might move the dye in and out of the beam offering fresh solution while letting the used dye recover. Purely made up idea. I vote pump or stir bar. No idea how fast the dye recovers or how fast the dye breaks down and pollutes the cell.

Why does a smaller cell work better? Would seem to work worse. I know very little about these lasers but they have fascinated me since I was a kid reading SciAm.

Looking forward to some pictures. Are you going use it for a projector?