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How I got my laser eye injury

funraniumlabs.com

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Re: How I got my laser eye injury

#271

Post by brianpan »

sebastiennight wrote: post #249
cwillu wrote: post #247

Earlier quoted context omitted.

‹twitches in metric prefix› 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.

This seemed like a wild claim (2500 watts for a tea kettle!? As much as a microwave oven in full blast?) so I looked it up. Wow.

The back of the envelope comparison isn't difficult. The energy in different forms are doing the same thing.

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.

Re: How I got my laser eye injury

#272

Post by cyberax »

amluto wrote: post #239
cyberax wrote: post #183

Earlier quoted context omitted.

> (Okay, 233nm is probably worse, but the available energy with a setup like this is much lower.) How do you get 233nm lasers?!?

Excellent question. You frequency-double 532nm and make a typo. I meant 266nm. 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 gett…

I understand the frequency doubling (/me points at my own eye damage).

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

Re: How I got my laser eye injury

#273

Post by xeromal »

mhb wrote: post #193
SkyPuncher wrote: post #95

Earlier quoted context omitted.

I agree with you. It's also pretty easy to figure out what you're talking about from context.

It's the second post in which he did this. And how should anyone know whether it's important to know what it means without knowing what it means?

I'm of the opinion that the guy or gal is giving us valuable information so let him rip instead of asking him to change stuff. If we can't google a simple acronym with the right context which we already know, we're on the wrong site.

Re: How I got my laser eye injury

#274

Post by nayuki »

cwillu wrote: post #247
oh_my_goodness wrote: post #224

Earlier quoted context omitted.

If it's a 1-micron wavelength laser with a 60 micron radius spot, the divergence can't be much less than about 5.7 mrad half angle. What makes eye safety tricky is just that 2.5 million milliwatts is a lot of power. Even when you spread it out some.

‹twitches in metric prefix› 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.

60 micrometres. "micron" is a deprecated irregular word that is unlike every other scaling of the metre.

Re: How I got my laser eye injury

#275

Post by chickenbig »

wbl wrote: post #262
porknubbins wrote: post #250

Earlier quoted context omitted.

Brits don’t mess around with tea I guess. I believe they’re mostly on 240v even for residential there. Correct me if I’m wrong but I don’t think it would even be possible to heat water that fast in the US on 120v.

They have a man watch the telly to hit the button to turn on the power for all the teapots going on. https://www.youtube.com/watch?v=slDAvewWfrA

That poor operator probably gets an adrenaline rush (and finger twitch) every time he hears the Eastenders theme tune.

Re: How I got my laser eye injury

#276

Post by beAbU »

ruined wrote: post #257
sebastiennight wrote: post #249

Earlier quoted context omitted.

This seemed like a wild claim (2500 watts for a tea kettle!? As much as a microwave oven in full blast?) so I looked it up. Wow.

british household AC is wild, it's like they've got a full-power american range plug for every outlet

Not just UK, the whole world except North America and Japan.

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

Re: How I got my laser eye injury

#277

Post by bleakenthusiasm »

somat wrote: post #42
relaxing wrote: post #7

Earlier quoted context omitted.

The sales guy set up the entire rig on his own? And no other engineers in the lab stopped to ask what he was doing? 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 indic…

The guy was listed as a "sales engineer" which on first glance is the worst sort of oxymoron, everybody knows engineers make terrible salesmen[1]. But perhaps it could work, just take your sleaziest engineer, put them through an intensive indoctrination in chicanery and lies and you get a salesman who almost knows what he is talking about. 1. How do you know if the guy trying to sell you something is the engineer. Th…

I've worked with a few sales engineers by now because I'm the person they try to sell to. I always saw sales engineers as the result of companies realizing that by now they often have to deliver sales pitches to engineers and not just manages managers and procurement folks.

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.

Re: How I got my laser eye injury

#278

Post by voidUpdate »

techstrategist wrote: post #205
voidUpdate wrote: post #114

Earlier quoted context omitted.

Even better is when the dancefloor wants UV lighting, so they just buy some cheap UV-C bulbs

What are the implications of that choice? Safety?

UV-C light is used for disinfecting, because it's very good at killing biological things

Re: How I got my laser eye injury

#279

Post by bleakenthusiasm »

sersi wrote: post #146
N_A_T_E wrote: post #109

I worked in a laser lab for a few months early in my career. After the safety training I fear lasers getting near my eyes in situations most people don't care about. I even look away from barcode scanners at grocery stores. Sometimes I wonder about lidar being shot in all directions from those self-driving cars around SF.

Should I be concerned about the lidar in my dreame robot vacuum (L10s ultra) and my 3 years old whose head is closer to the ground than me? I never thought about it before but you'r comment worries me.

So going by what they aimed for in building the laser: No. The nominal power and wave length of all of these appliances is less harming to the eye than going outside on a sunny day and forgetting your sun glasses.

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.

Re: How I got my laser eye injury

#280

Post by swiftcoder »

sebastiennight wrote: post #249
cwillu wrote: post #247

Earlier quoted context omitted.

‹twitches in metric prefix› 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.

This seemed like a wild claim (2500 watts for a tea kettle!? As much as a microwave oven in full blast?) so I looked it up. Wow.

I recently bought a 3500 watt electric kettle out of the bargain bin in LIDL, for around 20 euros. Europeans do not mess around when it comes to hot beverages
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