Hacker News Reader

Comment by BenoitP | Hacker News Reader

> efficiently converts optical power to electrical power

Damn, I thought it was just a copper pair going along the fibers. I hope they provide some thick safety glasses with that.

I don't know if it'd come out as laser light, but 600 mW puts it into class 4 (eyes are damaged at a few 100m distance):

https://www.lasersafetyfacts.com/resources/FAA---visible-las...

View on HN

That chart is for collimated lasers. There is nothing especially inherently dangerous about laser light, and 1.5W or so of light is common (your average household ceiling light is in that ballpark). A fiber break is a point source (more dangerous especially at very close range) and is a bit focused, but it’s not going to burn holes in your skin or cornea at any appreciable distance. If it’s a wavelength that penetrates to the retina, then maybe the fact that it’s a point source will make it more dangerous if it’s in focus.

You know, in some places there are warning signs that read: Do not look into laser with remaining eye (https://qph.cf2.quoracdn.net/main-qimg-1482f39eeb7fe2a2abc36...).

Anyway, common sense says you don't look with your unprotected eye through a fiber endpoint.

What does looking at a laser have to do with being safe from a class 4 laser? You could be two rooms over and be blinded by it if there are specular surfaces (which there usually are).

You probably still shouldn't look into the laser with your remaining eye, though.

Most fiber/transceivers you commonly find in a datacenter won’t cause eye damage:

https://www.nanog.org/news-stories/nanog-tv/top-talks/tutori...

(slides 79-84)

This is definitely not a most common transceiver, which is the point of all the commentary.

I'd refuse to buy this thing unless there was some national security reason for doing so, and then there would have to be interlocks on the room to de-energize it when anyone entered.

Disclaimer: I recommend you don't look at lasers as a standard practice.

For more context, an SFP+ 10G LR 10km module is Class 1 (completely harmless during normal use).

Same with a 100G LR4 type module.

The ZR type modules that run 100+km are also Class 1.

Pretty much any optical module you plug into a router or a switch is Class 1.

Where you should definitely be cautious is:

- Around optical amplifiers, where things can get into Class 2 and 3.

- DWDM setups where each module may be a Class 1, but the sum of their light adds up into something harmful.

They are class-1 only because the system is designed to not have any light visible during normal operation. Interlocks can be the only difference between a class-1 and a class-4 laser.

You dont have to look at the laser at all, scattered beam can be dangerous as well. Note: class 4 lasers have no upper bound, they are just hazardous.

Have these ever been weaponised?

You betcha. I remember in the late 90s an anti sniper technology that could detect lenses at long distances and fire a laser at them.

The idea was to mess up scope optics, but human heads have lenses too. It was not Geneva Conventions friendly.

Wow that’s pretty amazing. Wonder why I’ve never seen it in a film or tv show.

I’d love to read more about this. Especially the part about the Geneva Convention.

I’m guessing it was the Protocol on Blinding Laser Weapons.

https://en.m.wikipedia.org/wiki/Protocol_on_Blinding_Laser_W...

Experimentally, sure: https://en.wikipedia.org/wiki/Laser_weapon?wprov=sfla1

Big pewpews require big power and it's not super practical yet

US Navy has a few deployed and in use

https://en.wikipedia.org/wiki/AN/SEQ-3_Laser_Weapon_System

Wikipedia says that one is just one unit on one ship (moved to another ship). Has it seen more widespread production since then?

The end of the article mentions another system, HELIOS, but didn't have much more information, and that was only two units, I think?

I believe you, just wondering how widespread these are relative to traditional projectile weapons.

I think they are still in the testing phase but they are being deployed. The Marines do this all the time with all kinds of tech.

I've read that the main reason they like it is more about the incredible long range optics and not the laser, tbh.

It's against the Geneva Convention to use blinding weapons.

Sadly it's not against it to use killing weapons.

Has the Geneva convention ever stopped anyone? They can only arrest you if you lose the war, and people don't tend to plan for that.

General rule of thumb: if it's been banned, it's useless for the signatories. Ex: chemical weapons, but also biological weapons, land mines, and cluster munitions. Note that land mines and cluster munitions are still actively being used, especially in Ukraine, and the countries that signed onto the ban largely got rid of those systems well before the ban was signed.

It has. That's why countries don't have real chemical weapons anymore. They are easy to make (for an industrialized country), but they don't provide any real advantage when both sides in a war have access to them. They just increase misery for everyone involved.

Blinding laser weapons are in the same category.

That's not really the Geneva convention though, chemicals weapons are just not effective for any actual warfare (aside from committing atrocities).

I'm sorry but that is totally incorrect. Being able to clear out a building without damaging its capacity to provide cover is enormously useful.

Chemical weapons are incredibly useful, just awful.

The argument I've seen against their usefulness is that they only work against static militaries that don't have NBC training, and a modern military can already defeat threats like that without paying the political cost of using them.

https://acoup.blog/2020/03/20/collections-why-dont-we-use-ch...

> Chemical weapons are incredibly useful

They're not. They're effective against an unprepared adversary. Any real military will have anti-chemical-weapons tactics and protection.

So this happens: you douse a building with a gas, and then walk inside and get shot by defenders in gas masks. And by the way, you also will have to wear a gas mask yourself.

https://en.wikipedia.org/wiki/Dazzler_%28weapon%29?wprov=sfl...

They're "intended" to cause only temporary blindness

The application would be more civil than war-alike, if it existed.

That's even harder to prosecute, pretty much no one is starting a war over what rulers are doing to their own citizens.

Still need a major supplier both the laser emitters and esp. the optics. The weapons will be a lot more expensive compared to conventional weapons, or any anti-riot weaponry.

Aside the sci-fi vibe, I could imagine James Bond esque - still quite hard to use, has to aim for the eyes, scatter can cause collateral damage, doesn't work in fog, rain, etc.

They are called direct energy weapons, more like a sci-fi, though.

It'd be a rather short range weapon, that's not easy to aim, require a line-of-sight, can't penetrate armor... or goggles, or fog/dust.

I’m pretty sure high powered lasers penetrate goggles by just vaporizing them.

True but how would you deploy high powered ones and keep line of sight?

Use an X-Ray laser, as Larry Niven liked to use as a MacGuffin in a few of his stories

“Common sense”?

Never had one of those toys…

https://images.app.goo.gl/nFwVrEe26vkxxJWLA

I find these tremendously helpful https://i.etsystatic.com/13650636/r/il/617182/2062686717/il_... as popularized by AvE

What does that mean? I read it as people who have already lost an eye shouldn’t risk their only remaining eye, but I think I’m missing something.

It's tongue-in-cheek, implying that many people working with the stuff already lost an eye to it.

It's part joke and part telling people "hey, this stuff is really dangerous, take it seriously or you'll lose an eye, or both". I don't think I've seen a single lab with high-powered lasers that didn't have a variant of this sign.

A similar popular sign for chemical labs is "Carol Never Wore Her Safety Goggles. Now She Doesn't Need Them", depicting a blind woman with sunglasses and a white cane. (https://knowyourmeme.com/memes/carols-safety-goggles)

I think part of the joke is that damage is instantaneous so if you’re not prepared you can’t take evasive action.

On top of this, we can't see 800 nm light. That's well into the Infrared band so "invisible lightsaber for your eyes" is an exaggeration, but helps visualize what you could be dealing with.

I think that sometimes when humor is added, in this way, it is to make you pause first.

At least in my mind when I encounter something oddly said/written my mind starts suggesting contexts and I can clearly "see" myself going blind by doing me like things.

It emphasizes that you will only notice there's something dangerous around after you are already blind.

It's a very well worded warning, that spread because it's effective. The official warning saying that you must take precautions even if you don't see anything wrong just doesn't work well.

Yeah it's provocatively funny

Thanks. I must be awake too early because it didn’t occur to me the sign is a joke.

The joke being is that's not a joke.

It's a quantum joke

"Danger: Not Only Will This Kill You, It Will Hurt The Whole Time You're Dying"

Looking up the specs, the actual laser is 1.5W, the converted output power is 600mW.

The chart you linked suggests that it'll start fires if you accidentally break the fibre.

I have several lasers in that category somewhere in the depths of the electronics stuff i accumulated from hoarding and reselling it for years, including a surplus fiber laser i auctioned myself into owning. They can certainly start fires under the right conditions, but that requires the fiber end to be polished VERY well, otherwise, the beam isn’t focused enough to deliver the needed energy, bundled up on one spot. Still way enough to make you blind before you notice tho, nothing to skimp on in any case.

Probably the power would stop when the fault is detected.

800 nm (NIR) does present hazards. Most people can't se it until the intensity is very high, so you blink reflex doesn't protect you.

Having said that, it is probably highly divergent out of the fiber (depends on type). There's no risk beyond a few cm. Don't stick the fiber it up against your eye though.

To answer someone below its unlikely you could get burned except right at the fiber tip. You can stick your hand in a 1.5W beam as long as it isn't tightly focused.

Agreed. A 40W 1550nm laser I used in grad school would burn post it notes readily and slowly burn black painted objects. It gave me a little burn once too (Was like touching a hot stove). 1.5W focused to 100 um would be a zinger, but at 4 mm would be not super dangerous thermally.

The main risk is you couldn’t see it so no blink reflex to help from even specular reflections.

Regardless, it would be reckless to expose this to people without eye protection.

Could a fiber break in the wall ignite the sheath? What if the Sheath broke as well and it is up against the cardboard backing of drywall? Worst case, cellulose insulation?

Cellulose insulation is in fact very flame retardent. But to your question yes if the broken fibre was stuck against something flammable it could slowly ignite it.

I think your laser was 40mW. A 40W laser can engrave steel.

Beg your pardon, but I think I would know (PhD in experimental AMO physics).

It was one of these: https://www.ipgphotonics.com/en/products/lasers/low-power-cw...

Guy's name is literally rubidium!

Depends highly on wavelength and pulse length. IIRC the vast majority of laser engraving lasers are pulsed (the cheaper ones are probably qswitched) so 40W actually gives you peak powers much higher than 40W.

Igniting something is actually quite different from cutting or engraving. Lasers are often so good at cutting because they don't deliver enough energy to set things on fire, but enough inatantaneous intensity to rip molecules apart (have a look at comparisons between femtosecond and nanosecond laser cutting for example).

Judging by the fact that they mentioned being in grad school at the time and that the laser was infrared, I imagine engraving steel isn't too far off from what they were using it for.

But they mentioned it would slowly burn black painted objects.

It's all about absorption spectrum. 40W at 10600nm will burn clean through a few mm of wood but could only maybe lightly etch brass and be utterly useless on aluminum. 40W of energy is being delivered, what happens to the thing it's being delivered to is entirely dependent on absorptive potential.

Agree on the 3 orders of magnitude difference. 40W soldering iron will inflate post-it notes, 40W laser steel/stone engraving/cutting area.

"it is probably highly divergent out of the fiber"

Those of us in the styropyro discord have found that to almost never be the case. WEAR EYE PROTECTION AT ALL TIMES.

What types of fibers are you talking about?

Single-mode, multi-mode, etc. All fibers. Let's use my LASER marker at work as an example. Divergence in that fiber happens AFTER two things happen - first the photons need to leave the fiber,then they have to cross-over their 'hip' (where the collimated beam is tightest) THEN they diverge.

That's how fiber LASER markers work. I'm the operator of them where I work (I do everything outside of SMT - x-rays, LASER marking, high-voltage testing, etc.) Every LASER coming out of that fiber hits focal point about 2 feet past the fiber, where it begins to diverge.

Do not trust a LASER coming out of a fiber to be unfocused or not have enough power density to blind you. Period.

That's fine safety guidance but on the facts this is not correct.

For single and multimode fibers if it has a smaller focal spot some distance the fiber than at its tip you are talking about an assembly that includes the fiber plus an optic.

This is unambiguously true for single mode fibers. Multi mode one will diverge less

I could see there being some exception for a strange fiber which has a multi-emitter output, was nanostructured, tapered, etc..

"For single and multimode fibers if it has a smaller focal spot some distance the fiber than at its tip you are talking about an assembly that includes the fiber plus an optic."

A properly-shaped and polished fiber tip is already the optic. That's literally how it's fed into the galvo in a fiber-marking LASER. I'm also responsible for the maintenance on all equipment in the facility so I've had those machines apart more than once.

When you say most people, are there in fact people that can see this at low intensity?

Most (all?) IR lasers leak visible light too. Look into any 1310nm SFP module and you'll see red light even though 1310nm is well outside the visible range.

And no, this won't burn your eyes out. Despite what the clipboard warriors claim, a laser that's designed to couple to fiber will not magically focus itself at the exact distance where your eyes are located. Instead the beam will diverge as if the 1mW laser was a 1mW LED.

I can see 780 nm (rubidium laser cooling light) specularly reflected from an index card at maybe 100 mW, if memory serves.

> a copper pair going along the fibers

I learned the other day that this is actually a thing one can buy. Direct bury hybrid fiber copper, up to looked like 2 OS2 strands and 2 12awg copper conductors. It's fantastically expensive but might be worth it for certain applications, like cameras that are beyond PoE distance limits and also don't have power available.

I wish this was a broadly supported and mass manufactured standard and the industry had gone more that way ages ago. Optical for data and still have a couple plain strands of copper (no need for shielding, twisted pairs etc) for power. There isn't any particular reason it should be fantastically expensive beyond lack of mass manufacturing and standards. Ah well.

Honestly it probably only helps installation costs, and not by much. There are no code issues with running standard direct bury copper in the same trench as direct bury fiber, nor are there any code issues (iirc, I am not an electrician) with running them in the same conduit even. Plain direct bury OS2 and 12/2 or 12/3 copper is dirt cheap and the fancy cable they use for generators that has 12/3 plus additional current sense conductors isn't that much more expensive.

With 12AWG, depending on the cable type and rating, you can bring 20-30A (90C rated) of power to go with your fiber in the same pull. The cable might be expensive but I’m sure the use case is great for when you don’t want to spend $10,000 on bringing a service trunk and meter to where your network equipment is being installed.

OM4 fiber is rated at 10GB up to 500m or ~1800ft, and the amount of current that 12AWG copper could carry at that distance with acceptable voltage drop is pretty low, so you'd probably still need to be stepping the voltage up and down on each end. I looked into this recently daydreaming about building a small office in the woods.

> With 12AWG, depending on the cable type and rating, you can bring 20-30A (90C rated) of power to go with your fiber in the same pull.

Wire size is calculated off the 75C column of the ampacity table (NEC 310.16) so #12 wire is only good for 25A.

The reason being, there are almost no circuit breakers rated for 90C, the terminals/lugs are only rated for 75C in nearly all cases.

Forum thread w discussion: https://forums.mikeholt.com/threads/90-degree-or-75-degree.2...

For residential, yes, but commercial is a different story. Schneider will happily sell you 90c rated equipment beyond the wire. They provide excellent guidance: https://www.productinfo.schneider-electric.com/0110db9901wir...

I don’t think anyone needs shared fiber and 12ga cable in a home setting anyway.

The NEC also defers to UL and similar bodies for installations being cleared so the complexities go beyond the basic NEC guidance, especially for the exotic stuff out there.

I’m a commercial electrical project manager and I’ve never seen a spec call for 90C rated breakers. I bought dozens of panelboards last year from multiple manufacturers, including Square D.

You also need equipment lugs/terminal blocks/wire nuts rated for 90C.

I’m not saying 90C rated parts don’t exist, it’s just uncommon enough that you select wire based on the 75C column by default, even in a commercial setting.

Sounds perfect for long runs requiring repeaters/boosters or whatever kind of inline equipment that could be necessary

And power the network gear at the end of the fibre run at the same time

Even for remote connections requiring a data line, seems like supplying power via solar/battery. Otherwise, you'll get some asshat that plugs in their microwave and/or kettle and ruins it for everyone else.

Electricians hate this one trick!

> It's fantastically expensive

Right now you can buy 50m USB3 cables made of 'Active Optical Cable' which is a fiber data link with two copper wires for power.

Options start at ~$100 for 50m https://www.aliexpress.com/item/1005004105594973.html and prices go up to https://www.lindy.co.uk/cables-adapters-c1/usb-c449/50m-hybr... - not cheap, but considering how few they probably sell and that you're getting a special custom type of cable, kinda affordable.

Thanks for sharing.

I can't quite explain it, but... having not known of the existence of such cables, and despite the fact that it's good I don't have a use for one since they're not exactly cheap, there's something about them that makes me want to buy one.

I've really no idea why, but I even spent a few minutes wondering if there's anything I've never done due to not having a cable like that, but didn't think of anything.

(And it's not like I'm a cable collector or enthusiast or anything like that, generally!)

Move your desktop to the basement and use optical cables to connect your monitor and all the peripherals located in your room. This is one of the common use cases and it was popularized by Linus from LTT. He has optical Thunderbolt (PCIe and USB) at his desk and optical DisplayPort in several rooms. The latter allows screen casting without the usual compression artifacts, input lag, and low refresh rate that you get from shoving a 32gbps signal down a 1gbps pipe

Thanks! At the moment I'm enjoying my gaming PC adding a little bit of warmth in my home office that anyway needs heating constantly during the winter anyway... but would be tempted to get the PC out of sight in the future.

Any ideas of reputable brands for optical display port (and miniDP) cables?

Did a quick search and the first version was £80 for 10m / £100 for 20m on Amazon from one of those shitty, random name Chinese "companies" (in this case called "ATZEBE), which wouldn't surprise me if it was actually just the cheapest DP cable of the right length they could find rather than the real deal. (Not that I'd trust buying any cable on Amazon, even one they claim is sold directly by a company like Apple, considering Amazon's co-mingling system leads to any time they claim "sold by x company" has for years actually meant "one or more of the stock we have for this item is sold by the company that its claiming to be made by, good luck hoping you get one of the legit ones".)

And thinking about the two options that user michaelt linked in the comment I replied to just above you:

> "Options start at ~$100 for 50m https://www.aliexpress.com/item/1005004105594973.html and prices go up to [£450 / $570 USD for 50m at:] https://www.lindy.co.uk/cables-adapters-c1/usb-c449/50m-hybr...

To what extent is the expensive one the equivalent of an audiophile getting a placebo effect from using overpriced audio cables that make no difference in a blind test, vs. it being the price needed for a good quality 50m optical/hybrid USB cable while the cheap one linked on AliExpress might either perform worse, last less long, or be an outright scam like those fake USB storage sticks that are hacked to tell the OS that they have more capacity than they actually do?

AFAIK most optical cables are made in the same factory so it doesn't matter which one you buy. They also don't need controlled impedance like copper cables so it's pretty hard for an optical cable to not work

So buying that second option (the Lindy link) is really just wasting hundreds of pounds with zero benefit, apart from shipping speed, compared to the cheap AliExpress option?

FWIW, a 10m 5gbps optical USB cable is $70 in the US including 1-day shipping. Dunno why anyone would pay hundreds of pounds even with the euro/pound tax.

Also compare to data center hardware. A 10m 10gbps active optical cable is only $31 retail: https://www.fs.com/products/30895.html

Normally you'd buy optics and fiber (which is cheaper than copper ethernet cables of the same length) separately for data center use and in larger volume, but my point is that there's no expensive tech involved in these cables.

Cool, thanks for the reply

I bought a set of optical HDMI cables for my TV. Not because it's a long run, although it is, but because they're significantly thinner and I had to get four of them through a pretty small conduit. They're pretty nice, although I think the cable part is just fiber and each end is powered by the device.

There was a time they were suggesting structured cabling for new buildings, that ran power fiber and coax through the same ~1 inch cable. Because you didn’t know what you’d want and where you’d want it.

Yep, I remember seeing a variant with 2x Cat5e, 2x coax, and fiber. Iirc the argument against them was that they were a pain to install in typical residential framed construction because the bend radius in reality was like 3 feet (probably exaggerated, but not by much).

Having now done retrofit Ethernet install in a 75 year old house, if I ever build a new house it's going to have low voltage conduit from attic or basement to every interior wall and one or more big conduits from attic to a single home run location, itself with a dedicated 20A circuit.

Every time I have to touch wiring I think there's someone out there who could get rich figuring out how to make it easier to edit the wiring in finished walls.

Though I do know there's a company out there that makes manufactured 2x6 stud (tstuds is one name) that's basically 2 3x2's with diagonal pins between them. Quieter, less thermal transfer, and cheaper to make high R outside walls since the cost scales faster with length than width. Snaking a new cable through an interior walls made of that stuff would just require your typical fiberglass pole, with little to no drilling.

Maybe it can first check if something is on the other end before blasting full power

Yeah that's exactly how higher power (compared to 40km SFP modules) communication lasers work and why nobody wears laser goggles in a data center. Automatically turning the laser off when the other side stops responding is ancient tech

Something like what? An eye?

Something that responds to a protocol handshake?

So a freemason

blinks in IEEE

I think most high power optics do this already, right?

It does that, if I understand what I read about it a year ago.

This is 35% efficient. 1.5W in and .54W out.

That’s not efficient in my book.

That's a matter of perspective. Are you comparing to copper or to other electrically isolated power transmission tech?

A typical LED is 40% efficient and a typical solar panel is ~20% efficient. A typical Qi charger is ~50% efficient. I stopped using cables for portable devices a few years ago and use magsafe instead which is supposedly has 75% efficiency due to perfect alignment of the coils, but that's still nowhere close to the ~100% you get from copper cables.

I suppose if you're just running one of these, we are talking about 8 KWH per year wasted. There are devices in my home burning more standby power than that.

If you're running a whole cabinet of these then it's not the greatest.

And if infrared, you won't even see it, and even reflections can be damaging to the eyes in theory.

green lasers are scaring the heck out of me, each one of them is pumped IR laser and each reflection causes green beam and IR beam to diverge more and more

Reply on news.ycombinator.com