Laser Products I Hate | Hacker News Reader

Laser Products I Hate

funraniumlabs.com

81 pointspareidolia61 comments

Site is inaccessible for me, Google cache link: https://webcache.googleusercontent.com/search?q=cache:Ylgqkr...

With CSS:

https://www.eternum.io/ipfs/QmNopFQyLda1PeMJsqqPXYSVZxq8i2Xk...

Consumer lasers will be the spray paint of the next century. One small segment of the population will see them as an overly expensive way to accomplish tasks slightly more conveniently than the alternatives, and another larger segment of the population will use them mostly to trash their environment, leading to all kinds of weird attempts at legal restrictions.

No one has mentioned the obvious terrorism related issues with lasers. The worst body counts won't be individual random "makers" with poor coding skills and their bystanders, or even the cops, it'll likely be, say, an entire stadium instantly blinded, or really any public location, such as interstate highway overpasses or airport security lines. I suspect we'll soon have discussion on the topic of "weapons of mass destruction" as applies to lasers. Based on past experience, if some Saudi citizens snuck something in to the stadium (drone delivered?) then blinded everyone attending the Superbowl, would we invade Venezuela conventionally or nuke Iran?

On that note, does anyone have good resources on building laser powered products? I figured it would make sense to start by reading an optics textbook. [1]

Something like Building Electro-Optical Systems by Hobbs. First problem is that I wouldn't even know which ones good.

The next problem I see and which the article touches on is that the wrong setting might cause irreparable tissue damage. Which by extension means that making sure that the variance is power must have a bunch of failsafe circuitry more so than the average meditation eeg startup.

I believe there are reliability test scenarios for electrical equipment in space, so i assume there's similar things for this use case. Would anyone be able to point in the right direction?

[1]: http://eu.wiley.com/WileyCDA/WileyTitle/productCd-0470402296...

I have Hobbs, and it's a great general book. But it may fall into that fine literary genre of "explanations for people who already understand things." Hobbs assumes a fairly advanced understanding of physics and electronics.

You might be able to learn how to make gadgets that work at the prototype level, but designing a potentially dangerous product is engineering. I don't know how you do that without working as an engineer for a long time.

Disclosure: I'm a scientist who works in laser product development, among other things, but not a licensed engineer.

On a related note- do you know of any books that cover diode laser safety? Specifically, I'm working on a FMCW laser rangefinder (hobby project to teach myself more of analog electronics) and would like to know what is the maximum optical power I should use.

There's actually a good quick guide to this in the article: stick to the laser pointer classification of less than 5mw.

I'm more interested in things like: if the diode is on for half the time (50% duty cycle), can I use 10mW? if I transmit a high frequency chirp with even less total duty cycle, can I use even more power?

Not that it really matters in my case: I will probably scrap the project when/if I make a good enough amplifier stage and phase detector for short range where 5mW should be enough.

Well, Hobbs is also the place to go for how to make that amplifier stage. He has some articles online for photodiode front ends, that are quite informative.

Admittedly I've never looked into those issues because the gadgets that I've helped design are all Class 1 -- the system is fully enclosed and interlocked.

Which regulations do you have to follow / which standards do you have to adhere to when it comes to proving reliability of the developed laser product?

Also if Hobbs is a great general book, what would be an example for something more specific? I'm particularly interested in near-infrared lasers.

In the US, lasers are FDA-regulated. This is true even if they're not used for medical purposes.

I work with lasers and we get a yearly security training on staying safe with lasers (the whole shebang, videos of cow-eyes exploding from diffuse scattering of a cutting laser, cutting pizza, photos of scars of accidents, post-trauma photos of retinas etc).

It is indeed terrifying to see how easily you can get tools that can cripple people without people being aware of the danger.

I've spent some time in a lab with an optical table and what was probably a 10 mW helium-neon laser. Doors locked when the laser was on, warning signs, protective eyewear and strict procedures during experiments. And then you go out and see drunk people at parties with lasers from eBay of unknown power pointing them at random people. The lab experience made me really paranoid about anything that involves lasers and I completely understand the author of this article.

Exactly. I've even seen 'party laser' products at dollar stores with moving diffraction gratings that project patterns on the walls, marketed like a kid's toy (and I think with a Class 2).

Even worse, the EU norm for lasers has been amended for incoherent sources. Previously, LEDs had to fulfill certain maximal radiance requirements to not need a laser sticker. They raised the radiance limit for LEDs by a factor of 100 (so if it was coherent it's about a Class 3 now). I treat bright LEDs/flashlights like lasers now at close distance.

Edit: (someone could classify a Class 4 diode laser array for heat treatment as an LED array now (given shitty M2) and avoid the laser norms altogether, despite the thing still being dangerous)

Interesting that he compares them to firearms, and all that entails. With power levels increasing, we may see a viable laser rifle soon, and with it, a need for a new regulatory structure (or adoption and expansion of an existing one, atf, etc.) They seem to have many of the same public safety aspects, but will someone popularize a legitimate 'Sporting Use' for these devices before they are sold as 'Death Rays to Blind Everyone and Set the World on Fire', And deemed unsutable for mere mortals to own? I hope so. I guess based on this article, you could sell a kit without much liability.

> we may see a viable laser rifle soon

We won't. It's been a while since I compared the muzzle energy of a rifle bullet and that of a relatively powerful laser, and I don't have the time to dig up the comparison again right now, but the tl;dr: is that we won't see an even theoretically man-portable laser that can put a hole through someone for a very long time, if ever. Setting things on fire and damaging light sensors, sure - but those tasks are absurdly easy by comparison with rearranging bulk matter.

A rifle has a muzzle energy of a couple kilojoules. So you're looking at lasers in the kW power range. I doubt that you could do comparable damage even if you could deliver comparable energy. Flesh doesn't conduct heat terribly well and vaporizing a centimeter of skin is not very lethal.

Sure, but who hasn't thought of turning their enemies into zebras?

Just throw an Arduino, some servo motors, a camera and some ML on it and you can keep the squirrels off your bird feeder.

edit: if it's not obvious this is a joke

I don't think so. Lasers are ineffective as lethal weapons (they are very effective as blinding weapons, which is probably worse and inhumane).

I don't know about you, but I'd rather be blinded than die.

I don't think you get a choice:

https://en.wikipedia.org/wiki/Convention_on_Certain_Conventi...

If I absolutely had to pick, and the choice was between 1) get shot and maybe survive; or 2) 100% chance of getting blinded - I'd pick the first one.

Why are you comparing a weapon that has to hit a whole person and misses to a weapon that has to hit a 5mm retina and somehow never misses?

It's not difficult to track eyes consistently using computer vision. It's not difficult to aim a laser beam using a mirror galvanometer. If you're struck in the eye with a UV laser beam, the blink reflex doesn't kick in - by the time you've noticed the pain in your eyes, it's already too late. The beam doesn't have to track with particularly high accuracy to cause certain blindness, especially if there's an array of beams.

A decent hardware hacker could build an area-denial laser turret in a long weekend with a couple of hundred bucks of parts. I hope to god that nobody ever does.

A UV-laser would be humane, since UV (and shorter wavelengths) will interact with the outermost portion of your eye - visible light or the near IR (up to 1500) is what your imaging system operates on and it's focused onto the retina.

Edit: Also, the blink reflex isn't fast enough to save you from damage if the Class is higher than Class 2 (and even then it's a roll of the dice, since there are some who don't have that fabled reflex).

Can you expand on why that would be humane?

Shorter wavelengths (UV, extreme UV) are absorbed at the surface of organic tissue (and many other materials) and lead to ablation or heat transfer at the surface. So with shorter wavelengths, it'll mostly scar the cornea, which can be reshaped again using short wavelengths with a LASIK.

It might also cause damage to the lens and lead to cataracts, which can also be partially compensated today by getting a lens implant.

These ways of damaging your eye are extremely more preferable than having your retina or your nerves damaged in any way, since for that, no method of remedy exists yet.

At a guess, it might be possible to at least partially fix the damage afterwards, by scraping off the damaged cells.

I wouldn't call that "humane", and it is a guess; it might not work at all. Nothing to do with war is 'humane', though.

You're right, my choice of words was poor there, I didn't want to imply that there are any humane weapons or ways to wage war.

I think what I was trying to say is that if I could choose the wavelength to hit my eye, I'd pick extreme UV.

A sufficiently powerful laser - over 0.5W - can cause blindness from diffuse reflection. A 100W laser fired into a room with white walls for a fraction of a second can permanently blind everyone whose eyes were open at the time.

cause

a) you can't see when you're being shot at b) it suffices if there is a sufficiently large (to you invisible) reflection within your field of vision c) you can automatically scan a whole field very quickly, invisibly, silently d) the laser spot gets larger at a distance, so the laser is not a pointer but a shotgun cone with 2m diameter

I think the thing is though that it doesn't. It just has to scatter off of something else in the wrong way, and boom.

Because lasers are usually continuous and even reflections are very dangerous.

I wonder how practical a portable laser gun would be, as I'm imagining a laser diode array would need to be amazingly powerful (I'm assuming much greater than the 40W version in the video?) and they'd require a very beefy power source.

It seems diode lasers are up to 60% efficient?

It looks like you can get extremely high power pulsed laser arrays though.

It's not so much the power as the total energy delivered that matters. So, in that sense, it will depend on the batteries (or whatever storage mechanism they use) as much as the lasers themselves.

Yeah definitely, I can't help but think the power source needed would be very heavy too.

Who makes you unable to help yourself? Say, one watt delivered onto the retina can do damage very quickly. One AA battery can easily supply that.

Sorry I wasn't thinking about a system capable of blinding people, those do definitely exist though. Also there are devices such as 'dazzlers' which are intended to cause non-permanent damage.

Yeah, we were talking about something really fun, like being able to melt a boulder or something. %^)

It's been researched in the 80s/90s. The best solution was a gas-dynamic laser with a Po-220 (the activity of U238 within its entire 10k years halflife packed into a time of two weeks) reservoir as a heat source.

Very interesting, I'd never heard of a gas dynamic laser before.

Edit: Is it the Stavatti device you're referring to? Apparently there are some claims that it was a hoax.

Oh thanks, I've looked into it again and it seems it's highly controversial. I mean, even if it wasn't a hoax, the design is pretty much infeasible if you need a heat source that you can only store for less than a week and that'll kill everyone within line of sight if its container is breached.

I also wonder how quickly damage occurs when using all 8 beams through to focusing lens.

What about 3D printed lasers?

I don't know, looks like an advertisement to me. Fun, dangerous, barely legal -- what's not to like?

Yeah, I don't really see the issue. People play with knives, operate firearms, use table saws, and cross the street in traffic all the time. The stakes are high in life, and if you're not careful you might poke an eye out with that thing, but what fun is a world where everything is engineered to be too dull to poke an eye out?

Because it's extremely easy to damage other people with lasers. Stray reflections can easily blind. It's one thing if you're in an enclosed space only able to hurt yourself, but most of the real world is not like that.

Agreed, and that's to say nothing of the speed at which blindness can occur. Then there's those pesky IR lasers which at the right class level can blind you in wavelengths you cannot see[0].

[0] Which to me has always been one of those "hard to believe things" and, indeed, I've never worked with an IR laser or tested this (nor would I be interested in doing so) but I can't think of something more terrifying (related to blindness, anyway) than walking into a room, looking at something, seeing nothing particularly interesting and then ... seeing nothing at all ever again.

> Stray reflections can easily blind.

To emphasize this point, since we're talking about a 450nm laser at either 500mW (maybe just barely low enough to hypothetically qualify as Class 3B?) or 800mW (probably Class 4?), any stray reflections could easily cause blindness before the eye can respond by blinking.

Any laser powerful enough to burn or cut is a "why did my eye make a popping sound"[1], risk, not the "blink oww! that's bright!" that we are familiar with.

[1] the sound is a spot on the retina explosive boiling after the laser heated it extremely rapidly past 100C

Here's a video of a public axe throwing contest with amateur participants, no backstop, and people directly behind it.

https://youtu.be/EeiMvKuXs0E

People endanger the public at large all the time, knowingly or unknowingly. There is no decent world in which acts which merely pose a danger to the public are illegal before they cause that danger.

People instinctively understand the risks of throwing things, even sharp and heavy things. People do not have an instinctive understanding of the risks of lasers. They may both be dangerous, but that does not mean the two levels of danger are the same.

Also animals like cats might actively try to catch it.

Because the selling point is public use: its not just dangerous for the operator, but goes out of its way to invite bystanders.

Public use? As in use in public spaces? Rooms with unclosed windows? Well sure, that's unsafe and you should tell your customers not to do it, but you'd be crazy to think that permission is what's stopping people from dangerously operating lasers these days.

And what about the bit where he says that it's "the wild west" (mythicized time when, in actuality, homicide rates were not really that high, especially for the time) or "mad max" (completely fictional Australian motor fantasy).

The things that actually prevent laser related injuries from being a common health problem are a) common knowledge about laser safety (usually explained thoroughly by manufacturers), and b) the relative obscurity and lack of particular interest in high powered laser devices.

Drop your butterfly knife, you might just hurt yourself. Knock over that Cubiio, you might blind your neighbor in the building next to yours.

Hmmm - one serious thought - 'makers' thinking of playing with 1+ watts should also seek out videos of what happens to normal consumer and better non laser grade optics when used as focusing or steering elements - I knew of a lab that basically had very fine powered optical glass blown into the nearby walls (it was empty during the test) - and one less serious thought, from the same lab where I first encountered this sign... "Do not look in the laser with your good eye" :-)

The Cubiio (which is at the focal point for this hard-to-browse article) also gets the AvE treatment here: https://www.youtube.com/watch?v=d7WmUXtizEA [video]). Not so good PR there, either.

I've got a 4x8 CNC router with a small 4W laser diode that I can add on for light engraving work. Discussions of safety, protective eyewear, interlocks, shielding are all very valid. the stray reflections cutting wood in open air mean that there is significant scatter. The other day I attempted to engrave cork and found the scatter to be terrible.

BUT, all of that can be managed with shielding, eye protection, and walls. When the laser is on, I've rigged mach 3 (CNC control) to turn on some lights at the top of my staircase so that nobody comes into the garage without protective eyewear. It is absolutely possible to be safe without also limiting all your freedoms. In general, safety standards and workshop use-cases are well aligned, and if safety is too much work then a lack of safety is not about freedom, it's about laziness.

AvE has also taken a crack at Cubiio, and I think it is worth repeating some of his points, and my own observations here.

1. Diode lasers for engraving are VERY sensitive to focal length changes. If my surface that I am engraving changes more than 1-2mm in height, I try to compensate for that in the engraving tool path. My minimum line width is .01" with the laser/lens combo I have, and if I am out of focus even .125" (3mm), the line width will probably double.

2. many materials reflect terribly while cutting. Especially pre-finished light colored woods like maple. There is practically no way to avoid this. If I cut those I'll often end up with uncut areas in the piece because 100% of the beam ended up scattered, and didn't manage to burn the piece at all.

3. the idea is very tempting. It would be very nice to have this functionality, but, for the average maker, I think you would be pretty unhappy with the power this can make. I frequently want a LOT more than 4W, this appears to be about 1/4 of that. Most commercial systems from Epilog start at 20-40w. The Cubiio would probably produce shallow, uneven cuts at very slow feed rates with really long run times to produce anything useably deep. If you ran it at faster feed rates it would probably produce a laser engraving so shallow that it would rub off.

4. I want their app. The ability to turn scanned art into vectors for G code is something I would pay for. AFAIK there is NO good commercial solution for this. I have tons of line art that I would love to laser engrave but have no way to produce simple paths from it.

Edit: this is the laser I have - https://jtechphotonics.com/?product=3-8w-laser-and-2-5amp-sa... - I can vouch that it is well made and the vendor is great to work with - he assembles these himself and takes safety seriously.

this guy uses an engraving laser with copper film to quickly make traces/PCBs https://www.youtube.com/watch?v=GEABTyNZv1k [french]

So in addition to the Class 1-4, there should be Class "What remaining eye?"

Reply on news.ycombinator.com