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Laserbuilder's homebuilt ruby laser

Laserbuilder

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Long time ago I have found a quite big (8*120 mm) ruby crystal from a pulsed holography setup and a couple of big 5 kJ flashlamps. So, I immediately decided to try to build a ruby laser.

At the first attempt I tried to put the lamp and the ruby crystal into a cylindrical glass reflector. I knew that the lamp didn't match the crystal by size and the performance would be very low. The reflector with the mounts, lamp and the crystal formed the "laser core" as I call it. The laser core I'v mounted on a metal base and attached the adjustable mirror mounts on the opposite sides. At first I tried to use a full reflection prism as a HR and a random OC mirror. I took it to the spectrophotometer and measured 45% transparancy on 694 nm wavelength for it.

The power supply was a very crude and unsafe pile of electrical circuitry including a 1000 uF capacitor bank, microwave oven transformer and a single rectifying diode to charge the caps, an induction coil with an ignition transformer connected in series with the flashlamp. The flash energy could reach 4.5 kJ, but I saw no lasing at all. Here are the pictures of the first version.
 

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Laserbuilder

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When the first version of the laser failed, I rebuilt the laser into the second version. I purchased two 2 kJ lamps that ideally matched the crystal. I had to remake the mounts for both the crystal and lamps. The resonator mirrors I left the same. I connected both lamps in series, which allowed me to use them with the existing power supply. Then I've built around the lamps a box from white bathroom tiles, thinking that they will be good as a diffusive light reflector. And, after aligning the mirrors I got first flashes of red coherent light! The laser was working. At maximum pumping energies and with focused beam it struck sparks from pieces of iron.

though the laser was already operational, it was quite bad. The lasing threshold was big (at least 2 kJ of pumping energy), the white tiles quickly were becoming grey from very intence light, the crystal overheated quickly -- each new shot decreased output energy until seizing.
 

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diachi

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That's frickin' cool, again! Thanks for sharing with us. Love your DIY pump chamber, not ideal, but good idea nonetheless! :D
 
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Laserbuilder

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And then, accidentally I had found a shiny sheet of chromium plated steel. Of course, I wrapped it around the lamps instead of those tiles. The lasing threshold fell to 1.5 kJ, maximum output increased to, possibly, 2-3 J of laser light. Metal sparked quite spectecularly, when hit with the focused beam. The output energy became more stable and decreased only with the crystal overheating. Waiting 5 minutes between the shots for the crystal to cool down made the energy stable)))
 

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Alaskan

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Very cool, I have some ruby laser rods I bought a couple of months ago from 50 to 80mm length. Want to build something with them someday, I could have bought longer rods but decided to stay at a lower energy level for the flash.
 

diachi

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And then, accidentally I had found a shiny sheet of chromium plated steel. Of course, I wrapped it around the lamps instead of those tiles. Th lasing threshol fell to 1.5 kJ, maximum output increased to, possibly, 2-3 J of laser light. Metal sparked quite spectecularly, when hit with the focused beam. The output energy became more stable and decreased only with the crystal overheating. Waiting 5 minutes between the shots for the crystal to cool down made the energy stable)))

How many "gillettes" of power are you getting with the upgraded pump chamber? :p

(For those out of the loop" "measuring pulse power in 'gillettes'– the number of razor blades the pulse could penetrate")

Really cool how you've cobbled these things together, and they still work well. Goes to show it doesn't have to take a whole lot of special equipment or materials to get a DIY solid-state laser going.
 

BowtieGuy

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Amazing, I'm continually impressed with what some of our nembers can do, with so little to start with!
Anyone remember MacGyver, I think we may have a few of our own here at LPF? :D

Great job Laserbuilder! :beer:
 

Laserbuilder

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I have been thinking for a long time about improving the efficiency of my laser, when decided to shoot it into black rubber. I saw a burn, which consisted of two close spots... Very interesting. It looked like it was lasing in a TEM10 single mode... I decided to replace the full reflection prism, which worked as a HR with a conventional flat HR mirror for 694 nm, which I found in the rubbish bin in the optics lab with a pile of other mirrors. It was in a quite bad state, with holes burnt in the reflective coating. I glued it to the place and aligned the resonator. It made great effect! Th lasing threshold dropped to 900 J and maximum output increase at least by 2 times! I estimated the output energy to be at least 4-5 J with 4.5 kJ of pumping. Shooting an unfocused beam in the rubber causes a 5 cm flame out of it, focused beam drills a tiny hole through 0.8 mm thick metal sheet in 2-3 shots with loads of sparks. Such an increase in performance can be explained in a way that the laser beam became multimode with much more energy. The burn spot is more or less round. But, unfortunately it cannot be focused as tightly as the singlemode beam.
 

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Laserbuilder

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How many "gillettes" of power are you getting with the upgraded pump chamber?
I didn't really try to do this. It is very tricky to place them in the focus without good mounts, but it did penetrate at least two of them from a single shot, so the output energy can be lower than I expect.
 

Alaskan

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Могу поспорить, вы не проводите эту монету
 

Rivem

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Another awesome DIY build Laserbuilder. Very impressive!
 

paul1598419

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I am constantly amazed at your ability to get these difficult to find parts for free. I am truly envious. I loved the capacitor bank in the first post of photos. Quite a large bank. And finding these mirrors in the trash...I wish I had access to your trash bin. Building a pulsed ruby laser for portrait holography is one of my dreams. It may still happen, but it seems you have one built mostly with culled parts. Incredibly.
 
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Laserbuilder

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I am constantly amazed at your ability to get these difficult to find parts for free.
This is due to economical situation in our country. It is very bad, and Science in Ukraine died first, because it doesn't recieve any financing from both government and private investors. It has a whole chain of consiquences -- without any financing, people that are smart enough travel abroad and stay there. Those who are not -- give up scientific career and start doing something else that gives stable income, but not science. So we lose brain potential. And when comes a moment when a new company or business needs some research for something, or needs improving technology of something -- nobody can do it. So this company has to find someone who can do this research abroad and even on cheaper prices. It is a closed circle -- no financing-->no work for scientists-->no scientists-->scientific instruments become outdated-->no financing... A lot of labs closed down, ENORMOUS amounts of equipment were sold for nothing, scrapped, recycled (this applies to instruments containing precios metals like gold or palladium). And lasers and laser parts are among them. In our University there was a big laser lab with any types of lasers you can concern. 40 to 50 people worked there. It had at least 3 or 4 lab spaces and a personal 2 MVAR substation! You can imagine what lasers they had, that they needed so much electricity. And then it all was gone. Well, not all but 90% of it. When I was a student I was a frequent guest there. And everything that they hadn't time to scrap came into my hands either for free or for simbolic price.

In all Ukrainian scientific establishments situation is the same. It takes a lot of skill, luck and time to find appropriate contacts, to sniff out something interesting in the laser area and then trade it out on a bargain price. The rest of my laser stuff is a result of this "work", I look for old russian lasers throughout the whole Ukraine and abroad. And sometimes when I'm lucky enough I succeed.

Well, probably this post is more suitable for the collection thread.
 
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jors

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Simply amazing. I've really enjoyed reading your post. many thanks for sharing!! :)
 

HydroSean

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This is due to economical situation in our country. It is very bad, and Science in Ukraine died first, because it doesn't recieve any financing from both government and private investors. It has a whole chain of consiquences -- without any financing, people that are smart enough travel abroad and stay there. Those who are not -- give up scientific career and start doing something else that gives stable income, but not science. So we lose brain potential. And when comes a moment when a new company or business needs some research for something, or needs improving technology of something -- nobody can do it. So this company has to find someone who can do this research abroad and even on cheaper prices. It is a closed circle -- no financing-->no work for scientists-->no scientists-->scientific instruments become outdated-->no financing... A lot of labs closed down, ENORMOUS amounts of equipment were sold for nothing, scrapped, recycled (this applies to instruments containing precios metals like gold or palladium). And lasers and laser parts are among them. In our University there was a big laser lab with any types of lasers you can concern. 40 to 50 people worked there. It had at least 3 or 4 lab spaces and a personal 2 MVAR substation! You can imagine what lasers they had, that they needed so much electricity. And then it all was gone. Well, not all but 90% of it. When I was a student I was a frequent guest there. And everything that they hadn't time to scrap came into my hands either for free or for simbolic price.

In all Ukrainian scientific establishments situation is the same. It takes a lot of skill, luck and time to find appropriate contacts, to sniff out something interesting in the laser area and then trade it out on a bargain price. The rest of my laser stuff is a result of this "work", I look for old russian lasers throughout the whole Ukraine and abroad. And sometimes when I'm lucky enough I succeed.

Well, probably this post is more suitable for the collection thread.
Sorry to hear about your country and its budget cuts in science, but lucky for you, you get a bunch of free and cheap stuff!
 




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