 Yeah, my name is Sarah. I come from the region here. I live in the region of Karlsruhe. I work with lasers in my work and I developed things like this. This is an industrial laser system for marking pieces of metal, pieces of plastic in a line where products go through. In my free time, as she mentioned, I am in the FabLab Karlsruhe where we developed or built the laser saw, which is an open source project. So I have two laser sites, one at work and one in my free time. So I did an experiment with the CO2 laser in the FabLab. I wanted to know what happens when the beam goes on the skin. I went to a butcher and bought a piece of pig skins, five, six millimetres thick. And I put it on the laser and switched on the fume extraction and said, OK, I don't know where to start. This I come to later. And I ended up with this. On the top, you see 10% input power. At 1,000 millimetres minutes, writing speed. Second line on the top left is 50% of power and the third is 100%. When you look closely, you can see that the O's and zero's, the meat, the skin was lasered out and fell down. So then I was scared. I was really scared. It smelled like hell. I was close to vomiting. And I thought, wow, didn't expect this. And the second on the left hand side, the three rows, where with 8,000 millimetres minute marking speed. I don't want to have this on my skin or in my eyes. Definitely not. This I can't describe. I can't imagine the pain and the consequences, the medical consequences. So therefore, you are responsible for what you do with lasers. You everyone is personally responsible to wear the safety goggles to take care that no beam goes goes out of the compartment. So whenever you hurt yourself, don't take me reliable for it. Oh, Sarah didn't warn me about this and that. No, absolutely not. You are responsible. So read the standards. Read more, read some other literature. Think about what you're going to do. Seriously, think about what you're going to do. It is so dangerous or can be dangerous. And, yeah, obviously, before you switch on the laser system, please switch on your brain. This is vital. This is really important. So by the way, this was done with a CO2 laser at 10,600 nanometres. And I don't know the output, the optical output power, but the input power was maximum 100 watt. So I guess 60, 70 watts output power optical. Not nice. I came across some on preparation to this talk. I came across some some nice pictures and some nice stories I want to share. Especially what is very vulnerable is the eyes, obviously. Skin you can repair, you go to the hospital emergency room and you get fixed up with the eyes. It's more difficult, especially in the visible range of light. The top left image, there was a guy who had a setup at home. A one watt laser, a blue laser system. And it was standing on a chair. And he wanted, he did something. I read the story was very vague, but he wanted to switch it off. So he got off his chair where he was sitting to tinker with the system. And he stumbled upon a cable and the whole laser setup from the other chair fell over. And somehow he got the beam through his eye. This is one year after the accident. And I mean, imagine you have this huge spot where you see nothing. I mean, the brain can adapt. But I mean, such a black spot on one eye, you can't ignore this. You look someone in the face and you see black spot. You look on the traffic lights, you see black spot. So this was a very, very bad mishap. On the right, the right image is less energy with the near infrared laser. This is a typical YAK laser, 1,064 nanometers. That's a wavelength I work with at work. That was a short pulse. And this is something you might recover from, not that the retina recovers, but that your brain adapts to, yeah, take away this. I ignore this spot. I interpolate the image. I did the laser talk in autumn in in Darmstadt at the MIMCD. And I haven't had the CO2 laser at that time. I just had my laser from work. So I did the same experiment. I got from a butcher this piece of pig skin, placed in the focus area and said, OK, 20 watt, full throttle. Let's see what happens. And after one minute of marking a rectangle on the skin, I saw nothing. Well, I mean, I put my power meter, so 20 watts. So everything was right. Then I took my thermal imaging camera and so, wow, this is getting hot. Um, the the left you see on the on the left image, the range goes to 57 degrees. You don't see anything, but it goes into the tissue and heats up from the inside. This must be very painful. I don't want to to do it. I'm sometimes I'm tempted to go through the beam, but I'm I'm not going to do it just to to see the sense of the sensation. On the right hand side on the on the bottom, the this big red, this glowing blob was two, three minutes after marking this, what you see on the left hand side. And maybe you can read it, what I've what I've written below. This is hallowed hallowed world. You see nothing on the skin, but you can see it in the in the thermal image. Um, I find this very impressive and shows even with lower with lower energy, you can do a lot of damage. And this gives at that wavelength, this gives a lot of damage inside the tissue. Imagine you have you have your magnifier glass in summer and you you have the sun in the focus and you have your skin. This this starts burning and this is only minimum power. You have whatever how big the magnifier is. I don't know, give it a shot. It's it's very easy. It's very easy. You take you take a pot, pour in some water, put it on the on the oven, on the on the cook, on the cooker, heat it up and hold in your hand and then a thermometer and see when when the pain starts to become unbearable. So 60 degrees. So the question was at which temperature? I think. Yeah. Anyway, so this painful, I don't want to do it. I want to show you now. I talked about the danger of the optical radiation. We have we have two more two more dangerous sources of danger. One is when you handle a gas laser like a CO2 tube or different, different gas mixtures, you need to have a high voltage. The laser at the lab wants to have 3000 volts and we give them 30 milliamps. This is deadly. Simple. This is deadly. You touch it, you die mostly. The other thing is what happens when you apply a lot of energy, thermal energy onto whatever material it evaporates. And sometimes the the molecules, the bonding of the molecules break and then you have quite some funny things. I'm at a video with the with my laser at work. This is 1064 nanometers on a special cardboard, which is painted with a luck to to see if the geometry is right, if the pulses are right and so on. But what you see as well, I switched off the the fume extraction system, which you can see at the right hand side, the hose. The smoke that's coming up, this smells bad. And when you do, let's say, five to ten markings on this cardboard, you feel a bad feeling in your in your tummy. Now, imagine you have some other materials, you have plastics, which is a mixture of different, different elements and molecules and they break up and suddenly you have some some delicious things like cyanide, furans, dioxide, chlorine, formaldehyde. Not for me. So I don't want to smell this. I don't want to have this in my system as well. When you do do metal marking, you need to have a fume extraction when when you you mark on on stainless steel, for example. So it's not just iron, it's it's other metals as well. And it's in a lot of different metals. So it splits into the elements like nickel, chromium, manganese, cobalt, niobium, beryllium, lead and so. And when you take ceramics, you have the same yummy delicious content. So a fume extraction system is very, very important, very vital. If you do something in the in the region of material marking when you want to change the material. So if you just have a laser pointer and you chase your cat, so this this doesn't apply. This is only if you do something with the material. So there's mentioned standard. E N 11 50 11 5 3. This is I will come to standards later. This is a first introduction into the standards. A lot of things around lasers are standardized way of length to to energy and which class it gives. And so on. How think a protective material has to be how the the the glasses have to be to be made of, which answer quite a lot. I will come to this later. I'm going to talk about laser glasses now. Should now, not yet. Some funny things you shouldn't do on the top left side. Top left image. This was last year on in the hack center. I want to apologize to the to the check space to the Stuttgart hackers because we projected some some images at the wall above them. And I was a bit. Is it OK? OK. So I'm sorry for that. What you see is a four hundred four hundred milliwatt blue laser are standing on the on an empty seed DVD box on a on a bistro table, which was standing on the normal table. So it was about this height. And then we had to power supply and then we had to galvanometer control. And so we could deflect the beam. So if someone pushes it just a bit and everything gets misaligned so and someone walks by or doesn't realize it has a blue laser in his eyes. So remember the first first images of the eyes and gives a nice black spot. The image below I found in a book. Playing with the lasers. I was in the library and collecting my materials and I came across this image as no way. The subtitle was please don't look on to reflecting materials. In a book, you could buy officially for the youth to tinker with lasers. I mean, this is one of the most stupid ideas and I will tell you later why this is one of the most stupid ideas has to do with laser classes. And what you see on on the other side on the right hand side. I want to go to vacations. Excuse me. I wanted to go to vacations and I had quite a lot of work to do. Programming FPGAs on my laser system. So this is the internal of my laser system and this is at home. Because I'm a profane professional trained laser person. I thought, well, I have my safety goggles. I chase a cat away, close the window blinds and I did my programming work and every now and then I had to switch on the laser and to see if everything goes well. So the laser head, this is the gray box on on top. There the laser beam goes in there to go van meters with mirrors and then it goes through a lens onto the material where things where the magic happens. And this this brown thingy is a loud speaker. And what's round it round is a fiber reinforced tape. On the on the right hand side, you see an oscilloscope. I don't say which brand, but it's crap. No, it makes no fun. And what you see in front is the big box. There there happens magic electricity in light out and the rest is controlled electronics. So I had to to do some work at home. And if you don't know what you're doing, so don't do it, please. If you know exactly what you do, maybe you can do it. Talk to other guys and maybe you better stay alone in that room. Not to to harm anyone else. Right. Laser classes. Basically, there are less laser classes which are interesting for you. We have the latest classes you can see. But for you, as hackers, I think there are two, three laser classes interesting. One is laser class one. I don't know what the old school audio CD players have as as a class. But laser class one is you take your laser pointer and stare into it. And when you bought after half an hour, you switched off and nothing happens. This laser class one is interesting for for high powered lasers as well. I come to it later. Class two is what you have. What do you see here? What you tell the laser you chase your cat. It comes with something that's the called the eyelid reflex, eyelid closing reflex. So the theory is that when you get hit by this class two laser beam, your eye will close fast enough to avoid any damage. And that's a weak point of this theory. There was a big examination, a big test that had a thousand seven hundred people. And they were sitting on a chair and and wanted the face was monitored with a high speed camera. And there was a line, a laser line and coming down. And they measured the time between laser hitting the eye, coming onto the retina so you could see the laser beam. And to look away, you close your eyes, whatever. And only 20 percent of the people closed their eyes within these two hundred fifty milliseconds, which the eye, the closing reflex talks about. So 80 percent don't be are not in time. So there were people even who who needed one second to realize, oh, laser beam closing eye or looking away. And in that time, there can be some damage. So even this crap here, this pointer is not safe for the eye, even if you can buy it everywhere in a Photoshop or at a supermarket, whatsoever, be careful. Then we have class three. So there is a difference. The class is one and two, they have the M as well. And one is you can stand to it with a magnifier glass and everything is safe. And the other one is you can't use any optical instruments to be safe in that class. Class three is, yeah, it's a bit less dangerous than class four. It is that they talk about five times more energetic than class two. What's really funny is class four, everything up from 500 milliamps to megawatt, gigawatt. So this is you. This is a class you shouldn't have open like I did on my desk. But you can make it safe. You can have this gigantic health fire, which you have in a fusion reactor as a class one laser. You just encapsulate it. That makes sure that no laser beam goes out. Then you have a laser class one system. So the class is as well. This is according to the wavelength. We have the vision, the visible system, the visible wavelength. And you can see it goes up on the right-hand side where you can see that you have a higher region, which is safe within this laser class. This is region of the eye safe region, which is about 1500,000, 800 nanometers, something. I forgot the number now. We have also different damages on the skin in the eye, according to the wavelength. UV, you know, you are in the sun for too long or you like your tanning studio too much. You get burns on your skin. And when you have a UV lamp, you have your glasses, your goggles. So you have different types of photochemical reactions, of reactions of the skin, especially with the eyes. The UV, you have damage of the cornea. And the longer the wavelength, then you have, in UV, you have the damage of the lens. And then you have the damage of the retina. And the longer the wavelength goes, it goes back to damaging the cornea. So when the cornea is damaged, it's stupid. It's bad. But you might be able to fix it or the doctor might be able to have a new lens. But this is nothing you want to have, seriously. So, standards are very important. You can do, at home, you can do whatever you want. Buy your 50 watts, 100 watts, CO2 tube at the Chinese web shop, they are cheap. You lock your doors, you do what you want if no one else is in the room. As soon as other people are involved, you should read the standards. Which say, for example, the EN 6,825, number one, part one, has the safety things about a laser system. You have to have a proper housing. You have to monitor any openings. And when you open something, the beam has to be interrupted. And so, and you need to have, up from class, laser class three, you need to have a key switch for access control or magnetic card or whatever RFID system. In the lab, we want to set up an RFID system for the dangerous machines. So this would satisfy this standard. I could talk one week about these standards. They're very complex. They're very worth to read. You can read them. You can't, as far as I know, you can't copy them at the universities which have a technical department. So you go there, you ask for the standards, you ask in Germany, you ask for Dean EN, whatsoever. And the British, you ask for BS, EN, whatsoever. And so you can read them. And, well, it makes no sense to go through the standards. We can talk about it later in the HAC Center, if you like. If you design a laser system, there's some things you should look at. You should monitor every opening, every door. You should have an emergency system. It is a must-have, seriously. And you need to decide if you want to have an emergency shut-off or emergency stop. There are different ideas behind. You need to have a shutter, which interrupts a beam. You need to have some excess control. You need, very important, as we saw before, you need to have a fume extraction system. You don't want to have in your space all the chromium and burned wood smell. I mean, if we, before we had a filter system in the lab, when we cut wood, you could smell it hundreds of meters away, half a kilometer, you could smell, oh, in the lab there, burning wood. You need to do a risk analysis. What happens if something goes wrong? What happens if the laser source doesn't respond on, please shut off? And this and that, it's a long process of thinking. It has to be taken seriously. There's literature. You should take it seriously. You should document your project. And unfortunately, there is someone who has to sign for what you do, who's reliable for this. Finally, who can operate? I think on Hacker Spaces, who's allowed to operate the laser. So we will have a few short minutes. You will find me, if you want to have some questions, if it can help you with your laser design. I'm here, I'm at the hack center at the fail overflow. It's you come into the hack center very far at the right for the most corner. If you have questions, then we can discuss your issues, with lasers, no problem. I'm delighted to do so. Otherwise, please wear safety goggles. And if you have any questions, we have how many minutes? We are done. I'm sorry, hack center. Thank you very much.