Because it's a 2500 watt laser, if i didn't have laser safety curtains , the relections/etc could very easily blind someone at a fairly long distance.

The NOHD (nominal ocular hazard distance) is something like 10km (2500 watt laser, 0.06mm spot size, divergence is very very small). The actual hazard distance is shorter, but still, kinda crazy.

(as for why i have a laser welder - i got it cheap and besides the downsides above, it is very easy to weld ~anything without much skill. A person who has never welded in their life can weld sheet metal and have it come out basically perfect in 5 minutes)

2.5 kilowatts. It's called 2.5 kilowatts.

‹calms down›

2.5 kilowatts is how much power a tea kettle in the UK draws. It's an insane amount of power to pump into a 60 micron point.

Doesn't your microwave heat a cup of water in about the same amount of time as a tea kettle? And most tea kettles are bigger than one cup.

Now, think about concentrating the same amount of energy to heat up your eyeball. Or worse, concentrated into a tiny point on your eyeball.

Continental Europe uses 16A radial circuits so the current rating is higher there.

EDIT: Of course, you can't run two kettles on one radial, but you can on one ring.

Here in Singapore I think our pool pump uses three phase power, too. (Our plugs and outlets here in Singapore follow the British model.)

t = specific heat capacity of water * mass of water * degC deltaT / power

4.186 J/gC 1000g * 80C / 1800 J/s ~= 186 seconds

(I use mine mostly on the 90W or 180W settings, for defrosting.)

... but then i checked my eastern european kettle and guess what, it's ... 2.4 kW.

Almost all household appliances that heat (and specifically heat food or water) will operate at the limit of what your house can supply.

So that's about 1800 Watt in the US and about 3500 Watt in most of the rest of the world.

It's only natural that you see almost any (heating) appliance cluster around these numbers.

(I'm actually not quite sure where you would see 2500 Watt kettles. Perhaps some are deliberately neutered a bit, so that you don't blow a fuse in case you have anything else on that circuit?

Keep in mind that in the UK, but not in eg France or Germany, every plug also has its own fuse.)

Here in the UK, my home brew beer set up has a 3000w option - great for boiling 25 litres of water/wort - that said it came with a EU plug with some sort of 'fancy' UK plug convertor. After about 4 years the plug started to get so hot that it melted a socket or two - I found that inside the convertor the connection between the EU plug and the UK was really thin, which was causing it to heat up.

I cut off the end of the cable and rewired it to a heavy duty UK plug - it has been perfect since then - and no longer over heats.

South african plugs are rated 16A @240V. Thats a safe 3.5kW at each and every plug socket in the house.

Over here in NZ we get pretty similar ratings on the same style heaters, but the large room ones are 2400kW because we can get that from any socket.

Also with my hobby - sewing. A lot of people in North America talk about forgetting they left the iron on, but I switch it on and off every time because it heats up in 30 seconds - less if it’s been on recently.

That's eg common for electric stoves in your kitchen.

A lot of this comes down to wavelength. Some wavelengths get focused by one’s eye and can concentrate their power in a small spot on the retina. Other wavelengths will be absorbed before they get to the retina and will therefore deposit their power over a larger area and in less sensitive tissue.

It can also make a difference if the light is pulsed.

If you can't do this, you do need to panel or curtain the ceiling or use laser absorption coating or other things.

There are places that also just use reflection sensors that detect reflection on the ceiling and trigger (again, machines already support handling this). I have heard this works very well but have no direct experience with it.

All that said, reflection off ceiling is more uncommon for practical reasons (The angle at which you hold the gun to the piece, the fact that ceiling directed angles often become back reflection into the gun which it already detects, etc).

They already detect very high reflection as well.

For a makerspace, one of the issues you will have is that people will likely want to try to weld copper and aluminum a lot, both of which are highly IR reflective.

If you said "You can only weld steel and iron" you would eliminate a very high percent of reflection in the first place.

Here's a basic chart that looks right: https://www.researchgate.net/profile/Tomasz-Kurzynowski/publ...

For a 1064nm laser, you can see Al or Cu is going to reflect a lot of the energy, while steel/iron are still off the graph high in absorption

Here's a figure showing the quite stark difference. https://www.researchgate.net/figure/SEM-image-of-the-substra...

Agree with the post above, though. The safety setup for lasers is basically full isolation.

That is the only way to not blind your membership.

You absolutely, absolutely need this. Do not take chances. "Real estate is expensive" is not an excuse for a blinding hazard to members and visitors of your space.

I've worked with very high powered room-sized laser cutters before and they should all have a full room enclosure.

For others:

The NOHD is really a nominal distance. It's just the distance at which the beam falls below the maximum permissible exposure.

The 50% eye hazard distance (ED50) is 31.6% of this number. That is, if the NOHD is 100m, then at 31.6 meters you have a 50% chance of causing a medically detectable change to the eye. It's also worth noting - the beam power at this 31.6% distance is 10x, not 3x, what it is at the NOHD.

For laser welding, the spot beam is small (60um) which is one reason the NOHD distance is so high.

For reference, a laser pointer is like 1.5mm, so this is 25x smaller.

It also doesn't help that the lasers used are all ~1060-1070nm wavelength and so invisible as well :)

One of the fun parts when i lived in the bay area was that as companies got acquired, they didn't know what to do with the stuff they had before acquisition that isn't needed anymore, and it either sits in a warehouse, or gets auctioned off (or both!)

So for example, at one point, Google (after acquiring terra bella and some other companies) had like 5 or 6 very nice 5 axis VMC's sitting around collecting dust. Each was worth well over 250k. They already had plenty of VMC's in the machine shop, etc, and didn't need these, and it was not worth the trouble to sell them. At least back then.

In my case, I was able to get this welder for way less than half price.

The lightweld's have come down in price over the years, and that will keep happening.

They are pretty much the most expensive laser welders though, you can easily get one for 10k these days.

The truth is, however, if you go cheaper than this, what often what gets overlooked is safety. So some of them in the lowest price range don't even require you touch the gun to metal before letting you fire, etc.

All of them can weld the same, so if you go looking, look at other things too.

THe other thing - one of the nice things about laser welding is that it's improving very fast. So similar to fiber, running multiple types of lasers or optics in the cable is not particularly more difficult than running one. They just add more fibers (it's not quite the only issue, but you get the point).

Why does this matter? Because it means you can run another laser or something to monitor the weld and adjust parameters on the fly. Which lightweld and others are starting to do. So if you are moving the gun too fast/slowly, or got the power wrong or whatever, it will compensate automatically

This probably won't ever happen on mig/tig. The lasers are heavily computer controlled already, this just adds a feedback loop.

It also enables real time certification of a weld - see https://www.ipgphotonics.com/products/laser-weld-measurement for an example (this is a separate product, but you get the idea)

In any case, my take would be - if you want to play with them as a hobbyist, or have too much money, they are cool Otherwise i'd wait ~5 years and what you get will probably be 5-10x better for the same price.

Just from the top of my head: waymo develops their own lidars, akamai obviously needed a ton of machining for the kite, project loon probably had machined components. And those are just the flashy examples we heard about outside of the company. They can have ton of other projects which didn’t get to the point where we heard about them but required hardware prototyping.

I'm not saying that Google has machine shops purely for burning man. But I strongly suggest that when the idea has been floated in various locations, one recurring theme is "yeah let's! And let's get some lasers and propane burners!", and I also believe that some managers were thinking "great, this is the culture we want."

The register calls it "the chocolate factory" as a reference to Willy Wonka. Shame they descended into evil.

> I'm not saying that Google has machine shops purely for burning man. But I strongly suggest that when the idea has been floated in various locations, one recurring theme is "yeah let's! And let's get some lasers and propane burners!", and I also believe that some managers were thinking "great, this is the culture we want."

There was! It was the predecessor to the Garage. I suspect because the machine shop boys wouldn’t let them use the real toys.

Darn, we were trying to get a mill for the NYC office's makerspace. It was probably a safety issue and not a parts procurement issue, though.

Still, some of those little tracked tractors on TikTok are interesting. If I could somehow raise enough money to start importing them, I'm sure I could sell quite a few.

I'm black, but my wife did anoint me to the position of "honorary redneck" some time ago. Neighbor has stopped with the drone overflights of my property, but still, you're giving me ideas...

The materials cost is really not very high (no idea on the laser itself, but the rest is easily <1k. Probably <500.). The R&D cost was probably very high to start (but also coming down).

There were lots of mirrors and prisms and they has to calculate refraction off of them and stick carbon blocks everywhere that light transmission was less than 100% efficient so that no light could escape the system except via the target.

So after I got out I joined the National Guard.

How did that happen? Our MarDet would occasionally do live-fire training off the flight deck (CVN-65); they naturally pointed their weapons away from the ship ....

Or are you talking about hitting the hull of a different ship, e.g., one of the tin cans in plane guard, or alongside during an UNREP? Seems like that would ... get noticed by a lot of folks.

Also note how wide an angle "ship hull" represents both vertically and horizontally.

Not so 1 in a million.

Sure. That's why these safety officers exist. I think some other funranium posts state.that (paraphrased) "safety rules are written in blood."

That said, I suspect folks like that would tend to phrase the rule in a way to diminish the implied impact/likelihood, rather than enhance it or state as-is, as (afaict) the original did.

I thought the whole point of the Marines was to cause maximal amounts of damage. Are you implying there is a constraint on that?

But now I understand why the marines hate the navy: I had a buddy who'd been in the navy and he said they kept the kids busy by cleaning and painting everything but frequently they'd let 'em blow off steam by tossing cardboard boxes and stuff off the end the flight deck and shooting at them with the 50 cal machine guns.

We were good friends, attended MIT together, but if I thought the Navy would take many people like him I'd doubt their ability to fight a war. He was only in the navy because it would pay for school and AFAIK he managed to avoid getting any rank advancement at all. MIT requires, or used to, a lot of all nighters and he once said "I'm probably only sane with these all nighters because I did so much extra sleeping in the navy"

I hate to be pedantic, but technically the whole point is to expose the enemy to maximal amounts of damage. Whoever that is. Anything else is incidental.

I'm always happy to hear that there are people saying these sorts of things in the military. I'm sorry it wasn't fun at the time, but the Safety Officer really was looking out for you. You really don't want to be the unexpected cautionary tale, like Bob.

Somehow 3M was able to get out of compensating him for this workplace injury even though, if an ophthalmologist were to give him an eye exam (he tells me) they can literally read lithography writing (albeit backwards) burned in scar tissue on his retina. IIRC the prankster was never appropriately disciplined either.

Like OP it mostly affects/affected his peripheral vision and he just ignored it much of the time, but as he's gotten older his eyesight in general has gotten worse such that he can no longer compensate for it.

I swear they never used to be so commonplace.

Having worked nightclub lighting a long time ago I have a deep appreciation for laser safety haha

I would like to think that people would know today that laser pointers are weapons so this wouldn't happen, and that if it did happen, the schools' zero tolerance policies (the ones that you hear about used to stupidly expel someone for bringing a butter knife to eat their lunch with) would kick in, as school bullies literally damaging your body for life is completely unacceptable.

Often I would look at the ends of the fiber connectors to see if they were lit or if the light looked odd.

They were quite low in power but I'm surprised at myself that I didn't think of the risk.

edit: optics not options

Fiber used for long hauls is much more powerful but uses a wavelength that the human eye is very good at blocking (so your eye dissipates more of the energy but what does get through could damage your retina). There are systems that will decrease the power if the link is lost (cut or unplugged) to protect eyes. The light will still dissipate in free space (because there's no lens) so you should be safe from a distance. Single-mode fiber uses a more focused laser and more narrow fiber so it will spread less over a free space distance so don't get too close.

Always better to just use a light meter (or a phone camera) if you're unsure but also just holding the end of the fiber against some paper or your palm may reflect enough of the visible light to let you know the fiber is live.

The 1064nm exciter laser is pumped by an 808nm pump laser, and based on what I know about how inefficient lasers are, I can guarantee that those beams are way more powerful than the output beam! If those leak because the manufacturer cheaped out on filters, those lasers mat not visible, but they are still dangerous!

It's clearly a mostly true story that's been refined and polished over the years.

One of the current tenants there is Volvo Innovation Lab, which I imagine does laser testing. I have no idea if buildings need certain certifications for working with lasers, so I mention that tidbit.

As well, that office park has 16 buildings in it, by my count.

The pieces of this story very much so line up.

...or the guy was really called Bob.

Then again, occasionally real life really does happen unbelieveably, including when fudge-ups are involved.

Maybe what's most unbelieveable is that, to the extent the story tells, the only known injured person was the laser safety officer.

Presumably the safety person was partly in the loop on some other injuries, but maybe they're NDA'd on that, yet not NDA'd on mentioning the incident. Or, maybe an incident like that was kept very quiet by a company, and injured people never knew how they got injured.

Then there's this:

> It has been brought to my attention that I have never actually written this story down before, merely told it in person to many students for valuable lessons and also for laughs over cocktails.

Did they only give verbal reports and verbal depositions/testimony? Never wrote up a report for internal use or for professional publication?

"Laughs over cocktails" could mean finding humor in the ridiculousness of disaster, and taking a battle scar in stride. Could also be a hint that the entire story is a fabricated/embellished/appropriated story, like people often tell recreationally when drinking, and understood in that context for what it is.

I read that line as being in the context of the authors blog. As in “I’ve referenced this here before, and told the story to people in person, but never written out the story here on my blog.” Not literally saying that this is the first time in history any part of this story was committed to some form of the written word.

Or, the story might have started a bit like when grandkids ask grandpa how he got that arm injury, and instead of telling the troubling story about shrapnel in the war, or the car crash, he tongue in cheek tells a fantastic tall tale of fishing, when along comes a bear who wanted to eat his fish, chock full of lessons.

That could've been a goal with students: if one ran out of real-world case studies to drive home laser safety practices, a semi-plausible, if over-the-top, narrative of how a not-unlikely cavalier mistake could become a clusterfudge, with the story of course hitting all the safety practices they were just told about.

There would normally be verbal cues as to the kind of story, and there'd be the context of telling, both of which are lost in blog posts.

I know some places have poor safety culture, but this is a “laser company”. Basic laser safety should be drilled into them from day 1 and every day after. When I worked in an optics lab, we had interlocks on the doors that switched on with the power supply running the experiment and a sign outside indicating which wavelengths were operating.

1. How do you know if the guy trying to sell you something is the engineer. They will tell you in excruciating detail every flaw and design mistake in the thing and how they should have designed it better. Savor this moment, look past the terrible sales pitch and buy from them, for you have been gifted that elusive thing, the engineer.

I've also seen a different kind of engineer in sales, where they're paired long-term with salespeople. They sit in on sales meetings as a technical expert, and also do things like customizations and integrations. I suppose the presence of the salesperson helps suppress the engineer's inclination to start riffing on every flaw, but the pairing retains the engineer ability to help the customer be successful with the product.

You're walking it back a bit by saying you're a bit rough on sales, but what you actually wrote is engineers are bad at sales.

Sales engineer is a well-populated role, and they do their jobs as expected.

On average, an engineer will be worse at sales than a "pure salesman", but that's simply specialization in action. Can't get better at what you don't have an opportunity to practice. We all can do pretty much whatever we want if we put our minds to it.

In my case, that's exactly what they need. Sales people creep me out and make me want to hide under my weighted blanket. Sales engineers are the blessing that makes sales calls informative and bearable. I don't know how companies find and recruit them, but they make it happen and I'm very happy they do.

And sometimes you think what kind of shenanigans might happen and why it might be better to have complex safety interlocks that mate with entire automation cell controls...

Now would I do it? No... definitely not, as long as the demon on my right shoulder was being quiet that day.

But forgetting that, what are the core safety issues described? I get the direct exposure to unprotected eyes damage, but there's discussion of infra red reflections endangering nearby children + aircraft + casus belli with the US army.

“Could we use this to burn paint off the road” sounds exactly like the sort of question a person doing a demo might say “I don’t see why not, let’s try it” to.

While with deliberate thought about it, the fact that road markings are retro-reflective is obvious, but it’s not something you would necessarily consider immediately, since it’s called “paint” and almost all paint you encounter in the world is not retro-reflective.

For the rest of it, my reading of the story is multiple things happened here:

1) They initially aimed the IR laser at the paint on the ground. The paint being retro-reflective the laser damaged itself in about an half hour and stopped producing consistent results, just occasional spots of results.

2) The sales person rather than halting the demo to get someone else to take a look at what was malfunctioning continued to fire the laser after making various adjustments not realizing that because the laser had been damaged it was firing not at the ground anymore, but at the car a few spaces away.

3) They’d been messing with the laser after malfunctioning since before the VP parked their car, so there’s possibility they were sending lasers in the direction of the other building, so that’s one issue which would have been bad enough on its own but…

4) At some point the VP parked their car in the path between the laser and the building. As they continued to mess with the malfunctioning laser, they burned through the paint on the side of the car, exposing the bare metal underneath.

5) The bare metal is also highly reflective, but because it’s not retro-reflective the problem is now you had completely uncontrolled reflections. The ones that went backwards had nothing to stop them since there was only a fence and field between the lot and the school. And the ones that went up obviously also had nothing to stop them since they were outside.

6) Because of the unknown detections and quantity of reflection, in addition to getting all the potentially exposed employees and customers checked out, the company would also have to make advisory calls (at a minimum) to the school and the local airports and military installations.

Whether those schools and planes were actually in danger or not could not be said with certainty, but the point was less “oh know we’re terrorists now” and more “this was a huge screw up, and I need to impress on you why it was bigger than just breaking company property or not wearing your safety gear”

A good sales engineer knows a lot about the product within its normal operating envelope, but especially knows a lot about the boundaries of "normal operation". Bob's very first response to "can this thing do a thing [that Bob should know is outside of its normal operations]?" should have been to go ask the kind of engineer who is involved in defining "normal". And either the capability is investigated (and, if plausible, eventually a "safe" demo is put together, and maybe the definition of "normal" is expanded), or its revealed that it won't work, and that's that. In either case, the rest of the situation never happens, provided Bob is actually good at the engineering side of "sales engineer".

Should be, isn't.

I've heard of one place that had a class IV laser mounted on a robot arm in a public area, which turned itself off when the arm happened to flail in exactly the right way to hit its own emergency stop button.

The salesman, who deals with the business guys on the other side, the folks who will actually sign the check. The sales engineer, that deal with the guys who will actually use the product, is able to understand their requirements and come up with ways the product can fullfil those, provide Proofs of Concept, demos and initial training for those guys on the other side that will give the final ok to the business people: 'this will work for us, you can sign the check if you want"

The story sounds real.

[1] If all the bolted devices in the middle magically fall down, the laser would have hit my belly, not my eyes. So it's important to crouch looking away, just in case.

And with that kind of care, like turn everything off and still be very careful if you have to pick something from the floor.

Nd:YAG lasers always creep me out. I worked in a lab that had an Nd:YAG with two janky doublers: 1064 -> 532 -> 266 nm. The output energy was supposed to be a few mJ (IIRC), but it was basically zero. So the students operating it took off the second doubler and fired it at a bookend. Nothing (well, nothing visible). Took off the first doubler. After investigation, the zapping sound was the paint vaporizing off a computer at the other end of the lab, because the beam was actually scooting just past the bookend. 1064 nm is almost the worst wavelength you can work with. (Okay, 233nm is probably worse, but the available energy with a setup like this is much lower.)

I have a green laser pointer, and I made a point of buying a diode laser. It’s a slightly different color than 532, its battery life is better, but, critically, there is no way it could malfunction or be sloppily constructed to leak infrared light.

I just searched Amazon. There are plenty of green “diode” lasers, 532nm, ~100mW, for very little money. I don’t believe that for a second — those are surely crappy frequency doubled Nd:YAG lasers, probably unfiltered (that filter wouldn’t be cheap, and it might fail anyway under that ridiculous power level), and they will blind you when some funny reflection of the, I dunno, 500mW of stray IR light hits your eye.

Now that real name brand laser pointers are mostly gone, if you actually want green, get a 515nm laser or something along those lines. Stay away from 532nm!

Years ago when the hype wasnt really there he visited me and wanted to show off. I have 3 dogs and I really like this kind of tech but I forbid it to turn that thing on near me, especially in my flat. Even if they are directed away, the chance of unpredictable reflections is just too high for a bit of fun.

There are crystals that have nonlinear responses to high electric fields, and if you hit them with enough laser light, some of it comes out at half the wavelength. A lot of it also comes out at the original wavelength. Most 532nm lasers work like this, but other input wavelengths are possible, like starting at 532, doubling again, and getting 266nm.

This was a long time ago, and it wasn’t my project, so it’s possible it was slightly different, but I definitely remember the 532nm stage. And 266nm sounds credible for what the group was trying to do with the laser.

I'm just surprised that you were able to make a laser with such a short wavelength with frequency doublers (or triplers).

The lab I was in was doing this in 2000, and I suspect they got their frequency doubler from some other lab. It worked, but it certainly didn’t work well. The 1064nm laser was decently large (a couple J per pulse, from vague memory), and the expected UV energy was quite low. The laser was being used for some form of imaging at short range (fluorescence or absorption in burning gasses? Maybe Raman spectroscopy if everything got lucky?).

Fortunately I had the proper goggles on but was always terrified of catching a stray reflection and blinding myself. Now we live in a world of dirt-cheap high-powered diode lasers, and when I see all the stupid things YouTubers do with them with almost no discussion of proper eye safety, I wince.

Now I'm reminded of all the unregulated recklessness in some technical topics that I do understand, and realizing it's silly to assume.

I never thought about it before but you'r comment worries me.

The issue here I guess are malfunctions or rather cheap products with bad calibration. For total safety you'd have to get someone to measure input and output of the laser.

I'd love to reassure you about something like low input power, but at the end of the day with cheap products you don't know. If a higher powered laser was cheaper at the time of production, the extra milliwatts would probably be negligible compared to overall power consumption of the robot.

So the lidar is unlikely to immediately cause eye damage at a glimpse, but if your kid likes to chase the robot and thus might look into it for longer periods of time, maybe look into options of checking the laser's actual input power.

Also Yikes. Even with my low(ish) 1w-5w handhelds, it's self-evident that eye protection is needed when the beam travels less than a few yards.