Poor Man's Power Meter

[Draco]

I only posted it here because this was the lounge, and yes my doctor did know about, i should have used the term "blackhead" as that would have been more accurate, the heat from the beam melted the blockage to the sweat glands pore, since it was oil biased the heat facilitated it's coming out, my doctor wanted to dig it out with a tool and even that had failed, but to answer the question my doctor did indeed know about it

Sorry for the discretion of the laser as being "illigal" i won't do it again in the future

I deleted the post

[mixedgas]

When I first started into lasers, at 16-17, my pediatrician pulled me aside for a whole ten minutes. Never, Never, Never, and Never, a long list of "nevers". Some of which included, don't lase a mole, don't lase a wart, don't lase an eye etc.. Basically without a lot of training, you don't know what may be pre-cancerous. He had done a clinical rotation with laser surgeons, was quite up to date on this for the late eighties..

I kind of looked at him in Shock, as all I had was 0.1 mW at the time, HENE... Which was state of the art back then for beginners, laser diodes were something pulsed that existed only in textbooks.. But I listened..
.
RIP Dr. Hobansack, Medical Doctor Extraordinaire

Steve

[White-Light]

Bepanthen is supposed to be good for burns. However, you should use cream not ointment as ointment is oil based and can increase burning.

For severe burning, see a doctor obviously.

On the bright side, better a hand than an eye.

[Eidetic]

Sorry to hear about the damage to your hand made calorimeter. The worst similar thing I've done is try to measure a pulsed ruby output with a thermal detector. Worked fine with the ruby free running, but then my buddy turned on the Q-switch and POP, then smoke, then me comically trying to blow the smoke away from the optics. Nice ablation. Anyway, I'd try methanol for the goo on your OC. Alcohol often dissolves what acetone doesn't.

[planters]

Steve,
Maybe the "prospect" of a laser that could do what he warned you about actually got you more interested in them. I ordered that Molectron head...thanks.
The soft dressing is preventing any abrasion and the skin is not breaking down. God's dressing is the best.
The long wavelength, but not so long as to be absorbed by water is lucky as well.

I tried methanol with no luck. I examined the coating on the output side of the mirror and it has that concentric rainbow rings look that is typical of a damaged coating. My hand was only 8-10 cm from the mirror and the bright plume reached back to the mirror.

The mirror will still be usable for gross testing as the damage was not intracavity. And, this plano-plano cavity is going to be replaced by unstable cavity optics anyway. The divergence with such high gain in a stable cavity is too high. I am also going to need to think about optical enclosures. If an optic breaks as I keep increasing the energy from here, the risks of burning something or someone will become significant. Also, ANY dust on an optic and that's it.

[buffo]

10J/cm^2? And a 3 cm diameter beam? Holy death-star Batman!

The beam from this Goldenstar RGB plate that I've been fooling with is making just north of 8 watts, and at extreme distances (> 150 ft) the beam is diverged enough that it nearly fills the main area of my palm. (Call it 40 cm^2) So that's only 200 mw / cm^2 That being said, it is still *quite* warm and more than a little uncomfortable after just a few moments. At closer ranges it burns things like wood pallets and tree bark...

From your description it's clear that you were nearly 2 orders of magnitude hotter. No wonder you got branded! (Ouch)

Totally agree on the dry, sterile dressing. Although Lidocaine helps too... Hope you heal fast dude.

Adam

[planters]

To be clear, my estimate may be off. It actually looks worse than a typical 10J/cm^2 laser burn. On the other hand, to get to these fluences the medical lasers have to focus down to <1cm^2 and so there may be some recruitment with my burn because of the greater area to periphery ratio. On the other...other hand my hands are kind of tough and the thick dermis may be a little more resistant to the pulse.

After the expletive, I did smile because this IS so impressive. I am getting this energy at 2,500J input. The current capacitors will allow 5,500J and the monster in waiting will allow 24,000 J!

Earlier, the gain was so steep that I wouldn't want to think about what a full discharge would do (actually, I can't think of much else). I know from lamp testing that the pump output continues to increase with a slope greater than one but, as some researchers found, once you get up to output energy between 10 J and 100 J the thermal lensing caused by the the peripheral pump heating causes the output to saturate. The plano-plano optics cannot keep the laser within the tube and it is lost into the pump chamber. Unstable optics have been shown to be able to counter this and the power continues to grow. The divergence also drops one to two orders of magnitude as well.

Two kinds of unstable cavities are routinely used; positive and negative branch confocal resonators. There are some real crazy designs used for gas dynamic lasers, but the basic designs are relatively simple. In both of these the output beam emerges from around one of the mirrors. The annular output is spatial and both cavity mirrors are high reflectors. The advantage of the negative branch is that the optics are less custom and the alignment tolerances are greater. The disadvantage is that there is an intra-cavity focus and as the energy rises I suspect that I may need to consider air breakdown.

I just want us to be ready.

https://www.youtube.com/watch?v=kmO0WWtVt-M

[mixedgas]

Air breakdown looks scary, sounds scary, but is kind of timid as plasmas go...The plasma spot is really tiny. Of course at the powers your working at it may have a considerable shock wave.

Steve

[planters]

Of course at the powers your working at it may have a considerable shock wave.

I hope so. But, based on the demo Peter (krazer) gave at MIT, the effect would be to disrupt the wave front and prevent the cavity from lasing.

[Draco]

When I first started into lasers, at 16-17, my pediatrician pulled me aside for a whole ten minutes. Never, Never, Never, and Never, a long list of "nevers". Some of which included, don't lase a mole, don't lase a wart, don't lase an eye etc.. Basically without a lot of training, you don't know what may be pre-cancerous. He had done a clinical rotation with laser surgeons, was quite up to date on this for the late eighties..

I kind of looked at him in Shock, as all I had was 0.1 mW at the time, HENE... Which was state of the art back then for beginners, laser diodes were something pulsed that existed only in textbooks.. But I listened..
.
RIP Dr. Hobansack, Medical Doctor Extraordinaire

Steve

My doctor confirmed what the blemish was, he even tried to gouge it out, belive me my doctor did see the before and after, skin cancer runs in my family so he allways sees the oddites and has sent a few to the lab in the past, i really should have clarified that and for that i am sorry