We really need the diy hacker scene to come up with an open source design using pvc pipe, mirrors from old harddrive platters, and brass plumbing fixtures!
Check my other tutorials: - How to make nitroglycerin at home: th-cam.com/video/INUZdoGdF68/w-d-xo.html - How to hack your Sodastream: th-cam.com/video/rPGaBA_MUxs/w-d-xo.html - How to make concentrated sulfuric acid at home: th-cam.com/video/sJs31qK2ClM/w-d-xo.html - How to make concentrated nitric acid at home: th-cam.com/video/dIWXU520vnE/w-d-xo.html - How to brass plate and copper plate at home: th-cam.com/video/qIz58GGCbk8/w-d-xo.html - How to make a ball mill for black powder: - How to make a spectrum analyzer at home: th-cam.com/video/qVlI7pl02Ec/w-d-xo.html - How to make a robot that learns how to crawl: th-cam.com/video/F-kNXAFeffs/w-d-xo.html - How to intelligently solve a Rubik's cube: th-cam.com/video/2-UyZ9wnh7s/w-d-xo.html
@@edgardsalas8269 Calculating the power for this kind of application is tricky. Generally, a transformer AC to AC at 60Hz can achieve a pretty good efficiency of 95%, which you can approximate as 100% for simplicity. This means the power you put in the 220 V will be the same as the power that you get for the 5000 V. Now, how much power do you need? It will depend on the exact length of you laser tube and the exact pressure of the gas. Calculating it involves some theory of plasma which currently is not well understood, or for which we don't have good models yet. Also, the efficiency of a CO2 laser is about 20% if I remember well, so this means that you should supply an electrical power that is 5 times greater than output power of the laser that you want. Typically, you will want an output power for the laser between 50 W and 120 W. Once again, making calculations for such a system is not trivial, and you may just want to simply measure what you get.
@@edgardsalas8269 No, that wouldn't work for several reasons: - A CO2 laser operates at high voltages, typically in the range of several kilovolts. PVC is an electrical insulator, but not as effective as glass in this context. The high voltage could lead to dielectric breakdown of the PVC, causing electrical discharge or arcing, which could damage the tube or create safety hazards. - CO2 lasers generate significant heat during operation, both from the electrical discharge and the laser itself. Glass, is chosen for its excellent thermal resistance. PVC, on the other hand, has a much lower melting point (around 100-140°C) and could easily deform, melt, or release toxic fumes under the operating conditions of a CO2 laser. - A CO2 laser tube contains a mixture of gases, including carbon dioxide, nitrogen, and helium. PVC is chemically reactive with some of these gases, particularly when exposed to high-energy discharges. Over time, the PVC could degrade, releasing chlorine gas and other harmful byproducts, which would not only damage the laser but also pose serious health risks. In addition, the first achievement in building a homemade laser is to be able to generate a continuous discharge in the tube. You want to be able to see it before moving to the next step that consists of making it lase by aligning properly the mirrors. Using glass is not a big deal. I made mine out of old fluorescent tubes. I cut them by using this technique: th-cam.com/video/DBbTJqoNPUo/w-d-xo.html
Awesome video! One of the few I've actually found helpful! I do have a question though: what specifications do you have regarding the partially-reflective germanium mirror (aka, how much is "partially reflective"?)? And do you know any good sellers for these kind of mirrors?
I don't know, actually. I didn't do any search for these, I simply used mirrors that were available in my lab at the university. They were simply labeled as "germanium total reflective" and "germanium partial reflective".
So, a few questions: first, what happens as the laser tube's diameter increases to, say, an inch (worse performance, more output, more power required, etc.)? Second, will increasing the input current increase the laser output power (and if not, will raising the voltage increase output)? Thanks for any help you can give, this was an amazing video!
I don't think that increasing the tube's diameter can make the performance worse. However it is not clear it will make it better. What determines the laser beam is the geometry of the cavity, that is to say the mirrors' curvatures and the distance between the mirrors. So the requirement is that the mirrors' diameter must be greater than the beam's width. A formula for the beam's width can be derived, I don't know it by heart, I have it in my notes in my lab, but I don't have access to it due to confinement. Now increasing the tube's diameter obviously increases the number of atoms, and we might expect the number of excited atoms to increase as well. However, for these extra atoms to contribute to the intensity of the beam, they need to be on the path of the beam, which means that they need to move to the location of the atoms that just emitted. And the question is whether they will still be excited by the time they arrive inside the beam (otherwise that may emit spontaneously with a random phase in a random direction, and therefore have no contribution to the laser beam). For your second question, the problem is that there does not exist yet a satisfying theory that describes reliably the physics of discharge. So the best thing you can do is to measure the intensity of the laser beam, and increase the current and see which current gives you the most power. There will be a saturating value up to which keeping increasing the current will start to decrease the output power. And for your last question about increasing the voltage, the result will be the same as for the current: Voltage and current are not independent. If you use a current source that delivers the current that you set, the device will automatically increase the voltage until a current that has the value that you selected runs through the tube. You will end up with a function V=f(I) where V is the voltage and I the current, and f some function that is characteristic of the tube. If instead you use a voltage source, you will get the current I that depends on V with the inverse function f^(-1). The only practical difference is that it is safer to use a current source instead of a voltage source. The reason is that the impedance of the tube decreases once the discharge is initiated and the medium get ionized. That means that at constant voltage, the current may start to increase exponentially and blow up your tube. Typically you would have to increase the voltage until the discharge occurs, then quickly reduce the voltage to a value that is sufficient to maintain the discharge without blowing up the tube. With a current source, you don't have to worry about this. Simply set the current that you want and the source will automatically adjust the voltage in order to maintain that specific current.
@@andersdoverud9046 I'll have to measure it because I don't remember, but it's about 0.6 inch for the discharge tube (it was an old fluorescent tube that I cut). The cooling tube is about 2 inches (also from an old fluorescent tube).
Great video! Though i still have some questions. Is this important to use glass as inner and outer housing(or any dielectric will do)? What temperatures are normal for inner housing(should it be normal glass or temptress resistant one)? What actually determines the power of the laser(the current drawn by him at a given voltage)? Is there any fluctuations of a wavelength(does it radiate only one?)? Also i would be grateful if you could point out literature that is related to this topic.
I guess that any dielectric can be used, but the advantage of using glass is that you can instantly check if the discharge is occuring or not. I simply use regular glass coming from old neon tubes.
Thank you for giving answers for almost every question. I read them all and everything got much more clear for me. You are a real scientist ! Can you give me an advise, please. I want to build a laser for cutting metal 2-3mm thickness, what power of laser is needed for that? And is it possible to cut metal using such laser as you made? Just by increasing input power?
Is there a book I can read about this? Wondering about the principles, so I can figure out what would happen if you made the tube shorter without asking
I don't know about any book specific to lasers. I simply applied Maxwell's equations from "Introduction to Electrodynamics" by Griffiths to the particular case of a cavity formed by two spherical mirrors. The calculations are a little bit tough, but the result is the so-called "Gaussian beam", so you may want to search for that expression. Basically, the distance between the mirrors and their curvature must satisfy a certain relationship for the laser cavity to be "stable".
I built all the metal pieces myself using a lathe, and cut the glass tubes out off old fluorescent tubes. I found the mirrors in the lab at my University, so I'm not sure where to get them. For the failures, I either used a glue that was too hard, or my metal pieces didn't have enough gap to allow expansion, so the glass broke after a while when it got too hot.
@@BlueMoonshine Thks for the reply, It seems straight-forward but I don't really have a lathe for the end-caps: Basic Home-Built CO2 Laser Information www.repairfaq.org/sam/lasercc2.htm Homemade CO2 Laser Tube th-cam.com/video/5zpbXpHWSB0/w-d-xo.html
I think it would still work, but adding N2 makes the laser more efficient. The reason is that it is easy to excite N2 to its 1st excited state with a discharge. This energy state is almost equal to the upper energy state of CO2 from which the photons we are interested in are emitted. Thus, the presence of nitrogen helps to invert the population of CO2.
@@Reebox32 After stimulated emission, the CO2 is in a lower energy state, but not in the ground state. It remains in this lower energy state for a long time. During this time it cannot be excited again by the discharge because of the selection rules. Helium has an excited energy level that is nearly equal to the lower energy state of CO2. This allows CO2 to easily transfer its energy to the helium, and relax into the ground state and be ready to be excited again. This increases the performances.
It will work without helium, but laser intensity will be lower. Helium helps the CO2 to relax in the ground state once it has emitted a photon, so that the discharge can make it re-enter the excited state and be ready for a new emission.
I honestly don't know for sure. If there was a hard vacuum, then the electrons would hit the anode with an energy (q*V, with V=5000 volts) that is about the energy of an x-ray photon (E=hc/lambda, with lambda=1Å). But since there is some gas, they lose energy in it before hitting the anode. Probably some of them still make it to the anode without hitting the gas, but I believe that the fraction is small.
You need to use mirrors that are suitable for 10.6 micrometer wavelength. I used germanium mirrors that are suitable for low to medium power. For high power, you may want to use zinc-selenide mirrors, but these are more expensive.
No, it depends on many parameters, like the length of the cavity, the exact composition of the gas, the pressure, the alignment of the mirrors, the discharge current... And there is currently no theory of discharge allowing reliable calculations. The most reliable way of determining the power is simply to measure it, which I haven't done yet.
According to your observations and tests how to you estimate the power? Is it sufficiently powerful to penetrate into the thin plexiglass for instance or wood?
@@teximum I haven't been able to perform many tests yet, as the tube got cracked (the glue that I used to seal the aluminum caps might have been too hard, and the dilation of the aluminum cracked the tube when it got too hot), but the wooden shield that I used to prevent the beam from getting out of my optical table got burned. So it can definitely go through wood, especially if you use converging lenses (I didn't have any).
Yes, germanium mirrors are necessary (or zinc selenide mirrors) for the transmission mirror. For the total reflection mirror I read that simply using the disk of a broken hard drive works, but I haven't tried.
Interesting. Are there safety issues and risk of arcing from the high voltage side? The Chinese laser tubes look like a chemistry set on the inside and I always assumed that the spiral tube inside of those and the outer glass jacket was to allow gas expansion from when the inner tube heats up to prevent the tube from breaking. I’d be curious if the dimensions of this design and whether such risks exist from the aluminum caps getting hot.
As long as no conducting object is brought nearby the electrodes, it won't arc, even if the tube were leaking or broken. The voltage is enough to create the arc inside the low pressure gas, but not enough to arc across the oustide normal pressure air. The threshold electric field to generate an arc in normal pressure air is 3 million volts per m. Here the length of the laser is 50 cm, so we would need 1.5 million volts applied on the electrodes to generate an arc outside the cavity.
Yes, but the video for it will have to wait. As I was experimenting burning wood with it, the tube cracked. I believe that the resin I used to seal the aluminum caps was too hard, so the dilation of the aluminum due to the temperature increase put too much pressure on the glass. So I have to build another tube and use a different resin.
I would say that the laser wouldn't be lasing at all if the mirrors were not aligned. When you say that it emits two beams, do you mean two beams that are splitting apart from each other, or do you mean the superposition of two Gaussian modes?
@@letsfixit1594 I still believe that it wouldn't be lasing if the mirrors were misaligned. So maybe there is some dirt on the front semitransparent mirror that is causing some extra feedback to the cavity. Have you tried to clean it with alcohol?
I hope some one has not asked this question but I was wondering what the mirrors that are used in C02 cutting lasers are made of? They dont look like standard mirrors.. is it a silver polished coat?
awesome! If you would also teach us how to make ultraviolet or X-ray laser we would be able to cut glass/metal and be completely happy for the rest of our lives
What is the electrode made of is there any specific geometry for the tip of the electrode , wouldn't the rubber o-rings burn ? Why do manufactured CO2 tubes have three glass tubes , one in the middle is the gas tube which is inside the liquid jacketed tube and that's inside an even larger diameter tube that I don't know what its for, also why is the liquid tube spiraled around the its self. which parts of the whole tube create the most heat? And which parts are susceptible to heat damage . So many questions.
CO2 laser tubes don't require heated electrodes, so you can just use aluminum which has the advantage of being very easy to mill. The shape of the electrodes doesn't really matter, as long as you can raise the voltage high enough to initiate the discharge. Using pointy electrodes lowers the minimum voltage needed because it increases the electric field. Silicone rubber can withstand temperatures way above 200°C without deforming. I don't know why manufactured CO2 tubes have three glass tubes, but I suspect that one is meant to force the circulation of the gas, which leaves it time to go back to the groundstate from which it can be excited again. The population of the CO2 gas cannot be inverted if the atoms are not initially in the groundstate. The reason why the liquid tube is spiraled is probably to increase the surface of contact with the hot gas. I don't know much about all this, this is just a craft laser that works, but that is not optimal.
I believe the commercial glass tubes have three layers and the spiral tube inside for the following reasons. This is just my best guess. I believe the outer tube is connected with the inner tube and filled with the same gas and that when the gas in the middle heats up that it expands. I believe the spiral tube at the end (some lasers have it at both ends) is to increase the distance for the ionization path to prevent the arc from going outside of the center tube. I think the reason some tubes have the spiral at both ends is for redundancy in case the glass weld at one spiral breaks.
There is no focus lens in this design. If you want to add one, you can get some high power lenses here: www.ebay.com/i/172402335637?chn=ps&var=471231335423&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=471231335423_172402335637&targetid=474173460669&device=c&mktype=pla&googleloc=9025147&campaignid=6469981107&mkgroupid=79220281122&rlsatarget=aud-622524041198:pla-474173460669&abcId=1141176&merchantid=101737028&gclid=CjwKCAiA5o3vBRBUEiwA9PVzao9AMlA5loMkmSRwX1fwbwShxRGMqGdKQCvId4h4euG1IF248UUkNxoCUQYQAvD_BwE
Nice video, I was looking for a while for a description like that of the individual parts for this kind of tube. One question: what is connected to the water/gas inlets and outlets?
For the water, either you can fill up the tube and then seal the inlet and let the outlet open (to avoid cracking the glass because of water dilation), or for better cooling you can connect it to a bigger water tank and a pump to allow a constant circulation of water. For the gas, the outlet is just there to allow the air to go out as you fill up the tube. Where you believe that all the air has been pushed out by the gas, you can seal the outlet. Then, from the inlet, use a vacuum pump to adjust the pressure.
You can also use Gallium Arsenide, or Zinc Selenide which is more expensive but better for high power. I'm not an expert, so you may want to do some search about this.
@@BlueMoonshine how does one know what kind and type of mirrors to use ? they cannot be normal glass mirrors you find at home like broad band second surface ?
@@TheRainHarvester I read that they work pretty well for CO2 laser from small to medium power. However, you still need a one semi-transparent mirror, and the cheapest type is (I think) germanium, also suitable for small to medium power.
I didn't pay for anything, since I made it out of old fluorescent tubes, cut them myself, and used a lathe to build the metal parts. The only things I would have had to purchase were the mirrors, but I got them for free from the optical lab of my university. So I really can't give you a price.
I guess you meant "laser pointer". The principle is the same, an optical amplifier enclosed between two mirrors. In that case the optical amplifier is a crystal that is excited by running a current through it. I don't know the details about these types of lasers.
The glass is obtained from old fluorescent tubes. I cut them by winding a metal thread around them, then running a current across it to heat it. It just splits into a clean cut. There are some TH-cam videos on how to cut glass using different methods. For the metal parts, everything is made of aluminum that I cut and shaped using a metal lathe and a mill. The only parts that I didn't made myself are the mirrors, which I obtained from university lab's repository.
Thank you! But, some dimensions would help :-) (Length of the tubes etc. - cavity length? Maybe 3D model attached?). Can you explain the curvature (always see that the mirrors are flat). Power supply AC? If someone try to build it will it work? Power? Wave length?
Cavity length is specified at the end of the video: 50 cm between mirrors, each mirror with 1m radius curvature. Mirrors seems to be flat because they are small, but they are just a small part of a 1m-radius sphere.
Not for such a laser. Keep in mind that the length of the laser, typically 50 cm, is much larger than the emitted wavelength. Because of the spectral width due to the finite lifetime of the excited state, it is always possible to fit an integer number of wavelengths along the cavity length. This means that the cavity, whatever its length is, will always allow standing waves. However the cavity length must be suitable for the radius of curvature the mirrors, as specified at the end of the video.
@@BlueMoonshine ok this is something i never understood,why do they always refer to the wavelength as oppose to the distance between amplitudes? are these always the same in a sinusoidal wave? if you took a radio wave that has a long wavelength surely its distance between positive amplitude and negative amplitude is much smaller no? or am i not thinking this the right way? i always thought for example the smallest pin hole you can make in order to allow photons through must be the same size as the amplitude distance and not the wavelength or are these the same in light waves? so in what case does a laser cavity length need to be specific,only for small semiconductor diodes? and if the mirrors are plano? i heard curved mirrors are easier to align but are these curves based on sphere or parabola?
Hello, Nice co2 laser build! But how do you know the output power? We like to build 600wat co2 laser, but what i have read is that it will be connected with severral tubes off 200watt output power each.
The output power of a CO2 laser is typically 20% of the input power. With the size given in the above video, you can expect 100 watts of output power. 600 watts is a lot. I'm not an expert, but for such a power you may need to consider using transverse electrodes all along the tube (instead of the two longitudinal electrodes) and use a longer tube.
I used a 500 watt input power, but I didn't have time to measure what the actual output power was. The tube was on for a few minutes, then it cracked and blew up. That was a prototype that didn't have the large tube with water to cool off the lasing tube. I'm currently building a new laser following the design in the video.
Oke nice, We will do also some experiments and hope it will luck. Thanks for sharing the information and i will follow you when you put new things online! Thanks
Simply fill the tube to atmospheric pressure by connecting the source to the tube with a rubber hose to the inlet, and leave the outlet open for a while so that the air gets pushed out. Then seal the inlet and connect the outlet to a one-way fitting (letting gas out but not in), and use a vacuum pump to lower the pressure.
Helium is very important. It is used to (i) depopulate the energy levels of carbon so that it can re-enter the excitation process, and (ii) to transfer heat from the carbon to the surrounding in order to avoid overheating. The laser might still work without Helium, but not with optimal power.
@@BlueMoonshine , you are very knowledgeable! Where can I read about this gas mixture chemistry? Are there any good books on practical methods for making lasers?
@@TheRainHarvester The only thing I actually know pretty well about lasers is how to derive the Gaussian solution to the Maxwell's equation in a cavity. For the rest, you may find this PDF useful: www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=2ahUKEwik7q-JtNbjAhUIXKwKHfhwCzgQFjAAegQIABAC&url=https%3A%2F%2Fwww.boconline.ie%2Fen%2Fimages%2Fabout_laserline_tcm674-78853.pdf&usg=AOvVaw3Qcot98Q6J276ZbOHeWl8C
@@riksteen4933 I only did a quick Google search, but it seems that if you contact this company, your can order customized gas mixtures: www.alibaba.com/product-detail/High-quality-wholesale-calibration-gas-mixtures_62295050871.html?spm=a2700.7724857.normalList.37.46d02cefHat4ow
I'm not a specialist on that matter, but I would say yes. However, since energy does not come out of nowhere, you would have to deliver a higher voltage to generate the discharge. An alternative way is to make use of transverse electrodes all along the tube that allows to use a lower voltage (but higher current).
@@ARCSTREAMS Then the extra power will simply be wasted by exciting extra states instead of inverting the population. Those extra state will simply produce spontaneous emission of unwanted frequencies and increase the heat produced.
If you don't have a high voltage power supply, you can make one yourself. You'll have to build a transformer. Do a Google search, there are some tutorials.
@@shashanksingh8151 can, can't, the performance. do you need a pure gass? how long will it last? many details are a part of making a laser. it's not about buying a tube with a driver (that i'm almost certain came as a kit together) and hooking them up together
@@BlueMoonshine i don't remember putting this comment on this video, it was another video. where a dude had bought a completely ready laser kit. nvm this
Iam going to make one and I am impressed by your knowledge...I read most of your replies... Great job please give me your WhatsApp so that I can ask more questions regarding laser tube
So....to build a diy homemade laser, order the component parts of a laser and assemble it in your home? ....... BRILLIANT!!! Why didn't anyone else think of that?!? This click bait title is as bad as those 'diy build your own sensor' tutorials whos steps consist entirely of 1) buy premade sensors from amazon 2) plug into raspberry pi 3) flash this image to sd card. Literally nothing is learned. And even less was DIY'd.
We really need the diy hacker scene to come up with an open source design using pvc pipe, mirrors from old harddrive platters, and brass plumbing fixtures!
I'm actually working on it.
upped it and did not articulate on : 1) .5 m 1 m 2) germanium mirror 3) gas mixture and vacuum leaks 4) power and how to add lasers
Check my other tutorials:
- How to make nitroglycerin at home: th-cam.com/video/INUZdoGdF68/w-d-xo.html
- How to hack your Sodastream: th-cam.com/video/rPGaBA_MUxs/w-d-xo.html
- How to make concentrated sulfuric acid at home: th-cam.com/video/sJs31qK2ClM/w-d-xo.html
- How to make concentrated nitric acid at home: th-cam.com/video/dIWXU520vnE/w-d-xo.html
- How to brass plate and copper plate at home: th-cam.com/video/qIz58GGCbk8/w-d-xo.html
- How to make a ball mill for black powder:
- How to make a spectrum analyzer at home: th-cam.com/video/qVlI7pl02Ec/w-d-xo.html
- How to make a robot that learns how to crawl: th-cam.com/video/F-kNXAFeffs/w-d-xo.html
- How to intelligently solve a Rubik's cube: th-cam.com/video/2-UyZ9wnh7s/w-d-xo.html
Was absolutely great.
Thank you very much , good effort .
Hi, thank you very much gor the video. I will try to build. A consult, should I take care with the manipulation of the gases?, exists some danger?.
No particular danger that I'm aware of. I know that some companies sell bottles with the mix of gas ready to be used.
Thank you very much, last question, could the flayback be of 220v to 5000v a.c.?...but what power?, how I calcule it?.🤔
@@edgardsalas8269
Calculating the power for this kind of application is tricky. Generally, a transformer AC to AC at 60Hz can achieve a pretty good efficiency of 95%, which you can approximate as 100% for simplicity. This means the power you put in the 220 V will be the same as the power that you get for the 5000 V. Now, how much power do you need? It will depend on the exact length of you laser tube and the exact pressure of the gas. Calculating it involves some theory of plasma which currently is not well understood, or for which we don't have good models yet. Also, the efficiency of a CO2 laser is about 20% if I remember well, so this means that you should supply an electrical power that is 5 times greater than output power of the laser that you want. Typically, you will want an output power for the laser between 50 W and 120 W. Once again, making calculations for such a system is not trivial, and you may just want to simply measure what you get.
Other consult, could i use pvc pipes instead glass pipes?, would it works?
@@edgardsalas8269
No, that wouldn't work for several reasons:
- A CO2 laser operates at high voltages, typically in the range of several kilovolts. PVC is an electrical insulator, but not as effective as glass in this context. The high voltage could lead to dielectric breakdown of the PVC, causing electrical discharge or arcing, which could damage the tube or create safety hazards.
- CO2 lasers generate significant heat during operation, both from the electrical discharge and the laser itself. Glass, is chosen for its excellent thermal resistance. PVC, on the other hand, has a much lower melting point (around 100-140°C) and could easily deform, melt, or release toxic fumes under the operating conditions of a CO2 laser.
- A CO2 laser tube contains a mixture of gases, including carbon dioxide, nitrogen, and helium. PVC is chemically reactive with some of these gases, particularly when exposed to high-energy discharges. Over time, the PVC could degrade, releasing chlorine gas and other harmful byproducts, which would not only damage the laser but also pose serious health risks.
In addition, the first achievement in building a homemade laser is to be able to generate a continuous discharge in the tube. You want to be able to see it before moving to the next step that consists of making it lase by aligning properly the mirrors.
Using glass is not a big deal. I made mine out of old fluorescent tubes. I cut them by using this technique: th-cam.com/video/DBbTJqoNPUo/w-d-xo.html
Awesome video! One of the few I've actually found helpful! I do have a question though: what specifications do you have regarding the partially-reflective germanium mirror (aka, how much is "partially reflective"?)? And do you know any good sellers for these kind of mirrors?
I don't know, actually. I didn't do any search for these, I simply used mirrors that were available in my lab at the university. They were simply labeled as "germanium total reflective" and "germanium partial reflective".
Visit my webpage for more DIYs:
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So, a few questions: first, what happens as the laser tube's diameter increases to, say, an inch (worse performance, more output, more power required, etc.)? Second, will increasing the input current increase the laser output power (and if not, will raising the voltage increase output)? Thanks for any help you can give, this was an amazing video!
I don't think that increasing the tube's diameter can make the performance worse. However it is not clear it will make it better. What determines the laser beam is the geometry of the cavity, that is to say the mirrors' curvatures and the distance between the mirrors. So the requirement is that the mirrors' diameter must be greater than the beam's width. A formula for the beam's width can be derived, I don't know it by heart, I have it in my notes in my lab, but I don't have access to it due to confinement.
Now increasing the tube's diameter obviously increases the number of atoms, and we might expect the number of excited atoms to increase as well. However, for these extra atoms to contribute to the intensity of the beam, they need to be on the path of the beam, which means that they need to move to the location of the atoms that just emitted. And the question is whether they will still be excited by the time they arrive inside the beam (otherwise that may emit spontaneously with a random phase in a random direction, and therefore have no contribution to the laser beam).
For your second question, the problem is that there does not exist yet a satisfying theory that describes reliably the physics of discharge. So the best thing you can do is to measure the intensity of the laser beam, and increase the current and see which current gives you the most power. There will be a saturating value up to which keeping increasing the current will start to decrease the output power. And for your last question about increasing the voltage, the result will be the same as for the current: Voltage and current are not independent. If you use a current source that delivers the current that you set, the device will automatically increase the voltage until a current that has the value that you selected runs through the tube. You will end up with a function V=f(I) where V is the voltage and I the current, and f some function that is characteristic of the tube. If instead you use a voltage source, you will get the current I that depends on V with the inverse function f^(-1). The only practical difference is that it is safer to use a current source instead of a voltage source. The reason is that the impedance of the tube decreases once the discharge is initiated and the medium get ionized. That means that at constant voltage, the current may start to increase exponentially and blow up your tube. Typically you would have to increase the voltage until the discharge occurs, then quickly reduce the voltage to a value that is sufficient to maintain the discharge without blowing up the tube. With a current source, you don't have to worry about this. Simply set the current that you want and the source will automatically adjust the voltage in order to maintain that specific current.
@@BlueMoonshine Do you know that the optimal diameter is?
@@andersdoverud9046 No, I don't know.
@@BlueMoonshine Ok, thanks! :) What diameters have you seen been used?
@@andersdoverud9046 I'll have to measure it because I don't remember, but it's about 0.6 inch for the discharge tube (it was an old fluorescent tube that I cut). The cooling tube is about 2 inches (also from an old fluorescent tube).
Great video! Though i still have some questions. Is this important to use glass as inner and outer housing(or any dielectric will do)? What temperatures are normal for inner housing(should it be normal glass or temptress resistant one)? What actually determines the power of the laser(the current drawn by him at a given voltage)? Is there any fluctuations of a wavelength(does it radiate only one?)? Also i would be grateful if you could point out literature that is related to this topic.
I guess that any dielectric can be used, but the advantage of using glass is that you can instantly check if the discharge is occuring or not. I simply use regular glass coming from old neon tubes.
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Thank you for giving answers for almost every question. I read them all and everything got much more clear for me. You are a real scientist !
Can you give me an advise, please. I want to build a laser for cutting metal 2-3mm thickness, what power of laser is needed for that?
And is it possible to cut metal using such laser as you made? Just by increasing input power?
Very good illustration and good background music.
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Is there a book I can read about this? Wondering about the principles, so I can figure out what would happen if you made the tube shorter without asking
I don't know about any book specific to lasers. I simply applied Maxwell's equations from "Introduction to Electrodynamics" by Griffiths to the particular case of a cavity formed by two spherical mirrors. The calculations are a little bit tough, but the result is the so-called "Gaussian beam", so you may want to search for that expression. Basically, the distance between the mirrors and their curvature must satisfy a certain relationship for the laser cavity to be "stable".
@@BlueMoonshine Many thanks!
Thks,
?What was your successes/failure with the DIY laser tube?
If you were overall successful, ?Where can I find a list of parts & sources for them?
I built all the metal pieces myself using a lathe, and cut the glass tubes out off old fluorescent tubes. I found the mirrors in the lab at my University, so I'm not sure where to get them. For the failures, I either used a glue that was too hard, or my metal pieces didn't have enough gap to allow expansion, so the glass broke after a while when it got too hot.
@@BlueMoonshine Thks for the reply, It seems straight-forward but I don't really have a lathe for the end-caps:
Basic Home-Built CO2 Laser Information www.repairfaq.org/sam/lasercc2.htm
Homemade CO2 Laser Tube th-cam.com/video/5zpbXpHWSB0/w-d-xo.html
Amazing, interesting. I have a question. Would the laser work without Nitrogen? If not why not? Why is Nitrogen important? Thank you.
I think it would still work, but adding N2 makes the laser more efficient. The reason is that it is easy to excite N2 to its 1st excited state with a discharge. This energy state is almost equal to the upper energy state of CO2 from which the photons we are interested in are emitted. Thus, the presence of nitrogen helps to invert the population of CO2.
www.linde-gas.ru/en/applications/laser_technologies/laser_gases/index.html
@@BlueMoonshine Why Helium?
@@Reebox32 After stimulated emission, the CO2 is in a lower energy state, but not in the ground state. It remains in this lower energy state for a long time. During this time it cannot be excited again by the discharge because of the selection rules. Helium has an excited energy level that is nearly equal to the lower energy state of CO2. This allows CO2 to easily transfer its energy to the helium, and relax into the ground state and be ready to be excited again. This increases the performances.
What is replacement for Helium gas , or will it work without hellium ??
It will work without helium, but laser intensity will be lower. Helium helps the CO2 to relax in the ground state once it has emitted a photon, so that the discharge can make it re-enter the excited state and be ready for a new emission.
Can this laser emit x-rays ? i am trying to build one, but i am scared that this might happen since they work with high voltage and vacuum ?
I honestly don't know for sure. If there was a hard vacuum, then the electrons would hit the anode with an energy (q*V, with V=5000 volts) that is about the energy of an x-ray photon (E=hc/lambda, with lambda=1Å). But since there is some gas, they lose energy in it before hitting the anode. Probably some of them still make it to the anode without hitting the gas, but I believe that the fraction is small.
Nice explanation and clarification. I have a question what kind of mirrors are used for the laser
You need to use mirrors that are suitable for 10.6 micrometer wavelength. I used germanium mirrors that are suitable for low to medium power. For high power, you may want to use zinc-selenide mirrors, but these are more expensive.
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Good job!
Do you know what is the power of the output laser beam?
No, it depends on many parameters, like the length of the cavity, the exact composition of the gas, the pressure, the alignment of the mirrors, the discharge current... And there is currently no theory of discharge allowing reliable calculations. The most reliable way of determining the power is simply to measure it, which I haven't done yet.
According to your observations and tests how to you estimate the power? Is it sufficiently powerful to penetrate into the thin plexiglass for instance or wood?
@@teximum I haven't been able to perform many tests yet, as the tube got cracked (the glue that I used to seal the aluminum caps might have been too hard, and the dilation of the aluminum cracked the tube when it got too hot), but the wooden shield that I used to prevent the beam from getting out of my optical table got burned. So it can definitely go through wood, especially if you use converging lenses (I didn't have any).
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Is it necessary to use germanium mirror? Can it be done by ordinary mirrors?
Yes, germanium mirrors are necessary (or zinc selenide mirrors) for the transmission mirror. For the total reflection mirror I read that simply using the disk of a broken hard drive works, but I haven't tried.
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Interesting. Are there safety issues and risk of arcing from the high voltage side? The Chinese laser tubes look like a chemistry set on the inside and I always assumed that the spiral tube inside of those and the outer glass jacket was to allow gas expansion from when the inner tube heats up to prevent the tube from breaking. I’d be curious if the dimensions of this design and whether such risks exist from the aluminum caps getting hot.
As long as no conducting object is brought nearby the electrodes, it won't arc, even if the tube were leaking or broken. The voltage is enough to create the arc inside the low pressure gas, but not enough to arc across the oustide normal pressure air. The threshold electric field to generate an arc in normal pressure air is 3 million volts per m. Here the length of the laser is 50 cm, so we would need 1.5 million volts applied on the electrodes to generate an arc outside the cavity.
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hello, are there any tests of such a homemade laser?
Yes, but the video for it will have to wait. As I was experimenting burning wood with it, the tube cracked. I believe that the resin I used to seal the aluminum caps was too hard, so the dilation of the aluminum due to the temperature increase put too much pressure on the glass. So I have to build another tube and use a different resin.
@@BlueMoonshine I hope everything went well, it will be interesting. 👍🏻
Hi I have a laser tube emitting 2 beams i guess this is due to the internal mirror alignment, is there any way to realign them?
I would say that the laser wouldn't be lasing at all if the mirrors were not aligned. When you say that it emits two beams, do you mean two beams that are splitting apart from each other, or do you mean the superposition of two Gaussian modes?
@@BlueMoonshine It burns 2 seperate dots on the first mirror (on tape) they look about the same power level and are about 5mm apart.
@@letsfixit1594 I still believe that it wouldn't be lasing if the mirrors were misaligned. So maybe there is some dirt on the front semitransparent mirror that is causing some extra feedback to the cavity. Have you tried to clean it with alcohol?
@@BlueMoonshine I cleaned it but not with alcohol, i can send you a video if your interested.
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I hope some one has not asked this question but I was wondering what the mirrors that are used in C02 cutting lasers are made of? They dont look like standard mirrors.. is it a silver polished coat?
Germanium mirrors for small to medium power, or zinc-selenide for high power.
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awesome! If you would also teach us how to make ultraviolet or X-ray laser we would be able to cut glass/metal and be completely happy for the rest of our lives
The CO2 laser can cut metal!
Will you teach me how to make a laser tube ??
See my email.
I love the time we live in
Does your statement have any relationship with the present video?
What is the electrode made of is there any specific geometry for the tip of the electrode , wouldn't the rubber o-rings burn ? Why do manufactured CO2 tubes have three glass tubes , one in the middle is the gas tube which is inside the liquid jacketed tube and that's inside an even larger diameter tube that I don't know what its for, also why is the liquid tube spiraled around the its self. which parts of the whole tube create the most heat? And which parts are susceptible to heat damage .
So many questions.
CO2 laser tubes don't require heated electrodes, so you can just use aluminum which has the advantage of being very easy to mill. The shape of the electrodes doesn't really matter, as long as you can raise the voltage high enough to initiate the discharge. Using pointy electrodes lowers the minimum voltage needed because it increases the electric field. Silicone rubber can withstand temperatures way above 200°C without deforming. I don't know why manufactured CO2 tubes have three glass tubes, but I suspect that one is meant to force the circulation of the gas, which leaves it time to go back to the groundstate from which it can be excited again. The population of the CO2 gas cannot be inverted if the atoms are not initially in the groundstate. The reason why the liquid tube is spiraled is probably to increase the surface of contact with the hot gas. I don't know much about all this, this is just a craft laser that works, but that is not optimal.
I believe the commercial glass tubes have three layers and the spiral tube inside for the following reasons. This is just my best guess. I believe the outer tube is connected with the inner tube and filled with the same gas and that when the gas in the middle heats up that it expands. I believe the spiral tube at the end (some lasers have it at both ends) is to increase the distance for the ionization path to prevent the arc from going outside of the center tube. I think the reason some tubes have the spiral at both ends is for redundancy in case the glass weld at one spiral breaks.
I just made this quick video to explain what I perceive the glass design features to be: th-cam.com/video/DfpFbkrb_lk/w-d-xo.html
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Thanks for the info.
Laser 2suply problum baar baar kyo aa rahi h laser dena band ho ja rahi h kya problem ho skti h
good morning doctor ,geranium mirror is same reflect lens and focus lens at laser machine?
There is no focus lens in this design. If you want to add one, you can get some high power lenses here:
www.ebay.com/i/172402335637?chn=ps&var=471231335423&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=471231335423_172402335637&targetid=474173460669&device=c&mktype=pla&googleloc=9025147&campaignid=6469981107&mkgroupid=79220281122&rlsatarget=aud-622524041198:pla-474173460669&abcId=1141176&merchantid=101737028&gclid=CjwKCAiA5o3vBRBUEiwA9PVzao9AMlA5loMkmSRwX1fwbwShxRGMqGdKQCvId4h4euG1IF248UUkNxoCUQYQAvD_BwE
@@BlueMoonshine I am Thai people thank you share knowledge if you have time in Thailand please contract me thank you I am studying your vdo moretime
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Nice video, I was looking for a while for a description like that of the individual parts for this kind of tube. One question: what is connected to the water/gas inlets and outlets?
For the water, either you can fill up the tube and then seal the inlet and let the outlet open (to avoid cracking the glass because of water dilation), or for better cooling you can connect it to a bigger water tank and a pump to allow a constant circulation of water.
For the gas, the outlet is just there to allow the air to go out as you fill up the tube. Where you believe that all the air has been pushed out by the gas, you can seal the outlet. Then, from the inlet, use a vacuum pump to adjust the pressure.
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If i can't get a germanuim mirror what should i use instead of it ? By the way awsome video
You can also use Gallium Arsenide, or Zinc Selenide which is more expensive but better for high power. I'm not an expert, so you may want to do some search about this.
Maybe "France" mirror! .. ok sry for the bad joke 😁
@@BlueMoonshine how does one know what kind and type of mirrors to use ? they cannot be normal glass mirrors you find at home like broad band second surface ?
@@BlueMoonshine , would old harddrive platters be good for surface reflecting mirrors? They look incredible in the visible spectrum.
@@TheRainHarvester I read that they work pretty well for CO2 laser from small to medium power. However, you still need a one semi-transparent mirror, and the cheapest type is (I think) germanium, also suitable for small to medium power.
How to make nitroglycerin at home: th-cam.com/video/INUZdoGdF68/w-d-xo.html
About how much was the cost of the laser. I want to make it but am wondering about the cost
I didn't pay for anything, since I made it out of old fluorescent tubes, cut them myself, and used a lathe to build the metal parts. The only things I would have had to purchase were the mirrors, but I got them for free from the optical lab of my university. So I really can't give you a price.
Hey have u made d product ??
I did a long time ago.
What about laser point ? How it’s work ?
I guess you meant "laser pointer". The principle is the same, an optical amplifier enclosed between two mirrors. In that case the optical amplifier is a crystal that is excited by running a current through it. I don't know the details about these types of lasers.
Valéry Rousseau can you help me to make laser project ? I am looking to make laser pointer 1 km distance.
@@samofeelings7245 I'm sorry but I don't know anything about laser pointers.
Valéry Rousseau thank you so much
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where can you buy all the parts to build this. and can you list all the parts used in the video.
The glass is obtained from old fluorescent tubes. I cut them by winding a metal thread around them, then running a current across it to heat it. It just splits into a clean cut. There are some TH-cam videos on how to cut glass using different methods. For the metal parts, everything is made of aluminum that I cut and shaped using a metal lathe and a mill. The only parts that I didn't made myself are the mirrors, which I obtained from university lab's repository.
Thank you!
But, some dimensions would help :-) (Length of the tubes etc. - cavity length? Maybe 3D model attached?).
Can you explain the curvature (always see that the mirrors are flat).
Power supply AC?
If someone try to build it will it work? Power? Wave length?
Cavity length is specified at the end of the video: 50 cm between mirrors, each mirror with 1m radius curvature. Mirrors seems to be flat because they are small, but they are just a small part of a 1m-radius sphere.
Power supply can be DC as well as AC.
@@BlueMoonshine but isnt the length have to be precise in order to have standing wave resonance according to the wavelength or freq of emission?
Not for such a laser. Keep in mind that the length of the laser, typically 50 cm, is much larger than the emitted wavelength. Because of the spectral width due to the finite lifetime of the excited state, it is always possible to fit an integer number of wavelengths along the cavity length. This means that the cavity, whatever its length is, will always allow standing waves. However the cavity length must be suitable for the radius of curvature the mirrors, as specified at the end of the video.
@@BlueMoonshine ok this is something i never understood,why do they always refer to the wavelength as oppose to the distance between amplitudes? are these always the same in a sinusoidal wave? if you took a radio wave that has a long wavelength surely its distance between positive amplitude and negative amplitude is much smaller no? or am i not thinking this the right way? i always thought for example the smallest pin hole you can make in order to allow photons through must be the same size as the amplitude distance and not the wavelength or are these the same in light waves? so in what case does a laser cavity length need to be specific,only for small semiconductor diodes? and if the mirrors are plano? i heard curved mirrors are easier to align but are these curves based on sphere or parabola?
what is the program that you use ?. i wanna make laser but on my computer 3d
POV-Ray, Ubuntu Linux version.
Hello,
Nice co2 laser build!
But how do you know the output power?
We like to build 600wat co2 laser, but what i have read is that it will be connected with severral tubes off 200watt output power each.
The output power of a CO2 laser is typically 20% of the input power. With the size given in the above video, you can expect 100 watts of output power. 600 watts is a lot. I'm not an expert, but for such a power you may need to consider using transverse electrodes all along the tube (instead of the two longitudinal electrodes) and use a longer tube.
Thanks for the info.
So you used 500watt input power to reach 100 watt output (20% off 500=100)?
I used a 500 watt input power, but I didn't have time to measure what the actual output power was. The tube was on for a few minutes, then it cracked and blew up. That was a prototype that didn't have the large tube with water to cool off the lasing tube. I'm currently building a new laser following the design in the video.
Oke nice,
We will do also some experiments and hope it will luck.
Thanks for sharing the information and i will follow you when you put new things online!
Thanks
So why this laser is so expensive ? ;-)
Cause they are rare and are not in day to day use
How to put gases in a co2 laser tube
Simply fill the tube to atmospheric pressure by connecting the source to the tube with a rubber hose to the inlet, and leave the outlet open for a while so that the air gets pushed out. Then seal the inlet and connect the outlet to a one-way fitting (letting gas out but not in), and use a vacuum pump to lower the pressure.
Why glass? and why Helium?
is helium important If i can't get wath can replace
Helium is very important. It is used to (i) depopulate the energy levels of carbon so that it can re-enter the excitation process, and (ii) to transfer heat from the carbon to the surrounding in order to avoid overheating. The laser might still work without Helium, but not with optimal power.
@@BlueMoonshine so it also makes it a visible death ray too
@@BlueMoonshine , you are very knowledgeable! Where can I read about this gas mixture chemistry? Are there any good books on practical methods for making lasers?
@@TheRainHarvester The only thing I actually know pretty well about lasers is how to derive the Gaussian solution to the Maxwell's equation in a cavity. For the rest, you may find this PDF useful: www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=2ahUKEwik7q-JtNbjAhUIXKwKHfhwCzgQFjAAegQIABAC&url=https%3A%2F%2Fwww.boconline.ie%2Fen%2Fimages%2Fabout_laserline_tcm674-78853.pdf&usg=AOvVaw3Qcot98Q6J276ZbOHeWl8C
Are co2 lasers more powerful than ruby lasers if you use the same amount of power input
Where can I get the gas mixture
Ready-to-use mixtures can be purchased online. I don't have any link to provide, as my university took care of ordering some for me.
@@BlueMoonshine thank you i have search online but can not find it
@@riksteen4933 I only did a quick Google search, but it seems that if you contact this company, your can order customized gas mixtures:
www.alibaba.com/product-detail/High-quality-wholesale-calibration-gas-mixtures_62295050871.html?spm=a2700.7724857.normalList.37.46d02cefHat4ow
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Can you help me ? I start project laser tube mfg.
I don't know much more than what I put in the video, so I don't see how I can be of much help?
@KRONOS 1957 Were you expecting me to make a video in which I teach you how to make a laser by just snapping your fingers?
Tnx man
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Amazing
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THATS GREAT BUT CALIBRATION IS MISSING
Just tighten the screws to align the mirrors. It's an easy process for this type of laser.
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what about power of laser?
With this size of laser, and 500 watts input supply, you can expect roughly 100 watts output.
@@BlueMoonshine if I were to increase the size of the gas tube, would that make the laser stronger? In terms of wattage
I'm not a specialist on that matter, but I would say yes. However, since energy does not come out of nowhere, you would have to deliver a higher voltage to generate the discharge. An alternative way is to make use of transverse electrodes all along the tube that allows to use a lower voltage (but higher current).
@@BlueMoonshine wow 20% efficiency,not bad,,but what happens if you simply put more power in the tube without changing the volume or design?
@@ARCSTREAMS Then the extra power will simply be wasted by exciting extra states instead of inverting the population. Those extra state will simply produce spontaneous emission of unwanted frequencies and increase the heat produced.
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how can i get say 5000 v
If you don't have a high voltage power supply, you can make one yourself. You'll have to build a transformer. Do a Google search, there are some tutorials.
fuck, why do people keep calling these home made. they are purchased and assembled.
making a laser, includes MAKING THE FUCKING TUUUUUUUUUUUUUUBBBBBE
U can use an old tube light for that
@@shashanksingh8151 can, can't, the performance. do you need a pure gass? how long will it last? many details are a part of making a laser.
it's not about buying a tube with a driver (that i'm almost certain came as a kit together) and hooking them up together
Precisely, I made the tube with old fluorescent tubes, and used a lathe to cut the metal parts. What makes you think that this laser was purchased?
@@BlueMoonshine i don't remember putting this comment on this video, it was another video. where a dude had bought a completely ready laser kit. nvm this
@@darthnegativehunter8659 Ok! Thanks for watching! :)
muito bommmmmmmmmmmmmmmmmmmmmm.
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Iam going to make one and I am impressed by your knowledge...I read most of your replies... Great job please give me your WhatsApp so that I can ask more questions regarding laser tube
I'm sorry, I don't have WhatsApp!
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😎
Há! My 1K like!
Thanks!
@@BlueMoonshine From Brazil. Just to know. :)
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So....to build a diy homemade laser, order the component parts of a laser and assemble it in your home?
.......
BRILLIANT!!! Why didn't anyone else think of that?!?
This click bait title is as bad as those 'diy build your own sensor' tutorials whos steps consist entirely of 1) buy premade sensors from amazon 2) plug into raspberry pi 3) flash this image to sd card. Literally nothing is learned. And even less was DIY'd.
Where did I say that I bought the components of a laser? I built the tube from old neon tubes, and manufactured the metal parts with a lathe!
Just buy one.... They cost like 100 you would spend over 1000 to build one yourself and you have to be very good at this stuff
But for all their smug science and Greek letters they still don't have a fusion reactor that works.