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Homebuilt Manganese Vapour Laser (MnVL)

Laserbuilder

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Dec 4, 2016
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So, I have been away making a new fully homebuilt laser.

It is a manganese metal vapour laser. The laser tube is fully homebuilt. It is a self-heated tube. The main part of it is a ceramic bore tube with 14mm inner diameter and 60cm long. This tube is sorrounded with a layer of ceramic wool and then inserted in a wide quartz tube. At the ends of this tube there are electrode mounts machined from aluminium castings. Both anode and cathode are inox steel inserts. The electrode mounts are fixed on the quartz tube with flanges and fire-proof vacuum sealing gaskets. From the outside the quartz tube is sorrounded by another ceramic wool layer and outer aluminium tube, which serves as a backward conductor. Manganese metal is placed in two quartz vials inside the bore. Both mirrors are flat, the HR is aluminium coated, the OC is a flat quartz window. Both are attached to electrode mounts and faced inside the tube, so this is a tube with "internal" mirrors. Argon and helium are used as buffer gases. From the anode mount the gas is evacuated with a two stage rotary vacuum pump, from the cathode mount the gas is leaked inside the tube through a syringe needle. Gas pressure is monitored with a precise vacuum gauge. The laser is powered with my CVL power unit, which is homebuilt too. The laser tube draws 1.8-2 kW of input power to warm up, the pulse repetition rate is 10-12 kHz. The laser is started and warmed up with 20 Torr of Argon, than, when the bore is dark-orange hot, I shut off the Argon supply and let Helium inside. Optimal Helium pressure is 15 Torr. Quite soon the laser tube reaches its operating temperature, Mn metal starts to evaporate and lasing begins! The visible lasing line is 534 nm, very close to "common" 532 nm wavelength. Also there may be present some IR lines simultaneousely with the green one. I estimate the output power of my laser about 1 Watt at least, as it can burn wood and cardbord when focused. Some photos are attached, more can be seen here https://vk.com/album31425290_262758604
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Anthony P

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Oct 7, 2018
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Thank you for posting. This is truly inspirational. It is rare to see anything besides diode lasers here at LPF. While diodes are great, there is a whole other world of lasers out there.
 

paul1598419

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I had thought you moved on from here. Had not heard from you in quite some time. This is an impressive build, which is saying a lot, coming from you. I have enjoyed all your builds for the past two years, but this one seems to be even more impressive than the others, if that is possible. It is great to see you back here. :)
 

paul1598419

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I believe it is entirely possible that you underestimated the output power of this laser. I think it is likely to be much more than one watt.
 

Laserbuilder

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Dec 4, 2016
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Today I've loaded this laser tube with lead. The buffer gases are the same, operating temperature is much lower. Optimal PRR is low too. I saw lasing on 722 nm, it is still quite visible. It is a bright red spot with magenta tint. Output power was quite low, possibly some tens of mW. It couldn't burn anything when focused. Lasing exists till Helium pressure that exeeds 100 Torr. Lead also sputters quickly throughout the tube making the OC dirty. Also it is quite difficult to make adequate pictures of the laser beam. The camera doesn't pass over the colour correctly.
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CurtisOliver

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Jun 12, 2015
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Very nice Laserbuilder. Yes, even 808nm is still visible. Just much fainter, and much more dangerous.
 

paul1598419

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If lead contaminated the OC mirror, are the mirrors toast now? Will you need to replace them?
 




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