[entangledqubit]

Does anyone know whether eye safety is de facto maintained when your eye is being continuously bombarded by the 100+ scanning lasers being emitted from each of the 100 cars in the vicinity of an intersection? I'm on board with the case with a handful of lasers scanning by quickly but the energy may really start to add up in certain plausible future scenarios.

[dllu]

At 865 nm, laser eye damage is due to the laser being focused by your eyeball into a small spot on your retina. This is in contrast to other wavelengths, like 1550 nm, which do not get focused, but can instead damage the surface or your eyeball at much higher powers.

However, when there are many 865 nm lidars around, each one gets focused to a different spot in your retina, so it is not any more likely to cause damage than a single lidar. Thanks to the low power of the Ouster lidar, it is Class 1 eye-safe at any distance.

If there were a hundred high-power 1550 nm lidars all pointed at the surface of your eyeball, however, I wonder if it would be more likely to cause damage?

[dmix]

I just imagined everyone walking around with Google-glasses style AR lenses everywhere they go with LIDAR protection built-in!

[nullc]

865nm too, presumably it only passes as class 1 eye-safe due to an time x power x aperture exposure calculation...

I wonder how much we have to blame ITAR restrictions on >1555nm lasers for things like this not being more eye-safe on a by-wavelength basis.

[Reelin]

> I wonder how much we have to blame ITAR restrictions on >1555nm lasers ...

I tried looking up information about this (restriction details, otherwise feasible uses beyond that wavelength, etc) but it's hard for an outsider to quickly make sense of. Any chance you could elaborate?

[nullc]

https://www.bis.doc.gov/index.php/documents/regulations-docs...

The main section on lasers starts on page 47. The rules are very complicated. See 6A995 d and f.

Lasers are also covered in other sections like 6A205. (I'm amused by Raman shifters being covered-- they're literally just pressurized tubes with hydrogen and mirrors at the end-- I can't imagine anyone qualified to use one couldn't have one fabricated pretty much anywhere).

[dmix]

Reading law is always full of weird stuff like that, in between thousands of lines of monotany.

[sevencolors]

I've been asking this as well, I've never gotten a satisfactory answer. Other than "you can't see infrared".

I'm concerned once these become more prevalent on all cars or whatever else we stick these on. Curious if there's any studies on if it affects our eyes in anyway.

[agnokapathetic]

I swear I get persistence of vision artifacts when I see a LIDAR equipped vehicle, but need to run a double blind test to be sure.

[Calloutman]

Probably not. You can't see Ir Lasers.

[toxik]

IR and UV radiation can very much ruin your sight.

[runin2k1]

It doesn't matter if it is IR, UV, or visible. Only the power and duration matter.

Lidar uses very short pulses and very low power and is very safe even en masse.

[lmilcin]

This is actually more complex than that.

Due to optical aberration wavelengths outside of visible range don't get focused the same way as visible light. This means that the energy is spread over larger area.

Also, both UV and IR light is absorbed in a different way. UV tends to be absorbed much faster than visible light so that little of it reaches the retina while for IR opposite is true, the eye is more translucent to IR and only a portion of it is absorbed at retina and a lot of it tends to pass through it.

What it means is that, while a source of visible light is very well focused on the retina and absorbed in very small volume of retina cells, UV and IR are spread over larger area and then large part of it is absorbed somewhere else.

Still it doesn't mean IR or UV beams aren't dangerous. It is just that you can't directly compare beams by their power.

The way I understand it the main danger is that, since people may not see the IR or UV beam very well, there might be no involuntary response to close the eye.

[DaniFong]

Love these kind of analyses on HN (still where you can find them!) where someone will describe how the details matter.

Thank you to all involved.

If anyone can point me to the generalized best studies for safety margins and laser energy, please post links -- it's pretty relevant to a lot of AR designs to use laser projectors, and it is of course relevant to the lidar self driving cars at question.

[kyzyl]

Actually most pulsed lidar systems use pretty high peak powers, which result in an eye-safe average power only because they are on for a sequence of very short pulses (~1ns). It's pretty unlikely OP is actually experiencing vision problems due to lidars, but it's probably possible for some kind of weird interaction to happen in the eyeball due to the high power pulses. Even so, it's unlikely to be causing an damage, temporary or otherwise. I would hope it doesn't happen to him/her while driving or something, though.

[penagwin]

I'm being a bit pedantic - I'm pretty sure the visibility of the wavelength does matter (slightly) for lower power lasers, as visible lasers will allow your eye to react to the laser (by looking away) before serious damage - again only in low power lasers (like laser pointers).

If it's not visible I'm not sure that your eye will react quickly enough to prevent damage.

[nabla9]

Near/Bright thermal heater range is 780 nm – 1.4 μm.

Unless those heat lamps that also produce visible light damage the eye, I don't see how 865nm lidar could do it if the power is low.

[jdsully]

Laser light is much worse for the eyes because the energy is concentrated. It’s why you can buy 100W light bulbs but a 50mW laser needs a warning label.

[wutbrodo]

This doesn't invalidate your point, but the watt comparison you're making isn't correct. 100W is the power of the electricity input to the lightbulb, while the laser wattage is the power of the light output. The actual comparison would be more like 10W to 50 mW (which of course still means that the concentration of energy is required to explain the difference in eye danger).

[oceanplexian]

It’s just a relatively simple calculation of (amount of energy/amount of space) * time You could have a 100w laser pointed at your eye, but if it only operates for a femtosecond it would have no effect. The light isn’t worse or better than any other form of light.

[jdsully]

In electronics instantaneous power still needs to be accounted for. You can’t just average it out especially if its many orders of magnitude higher than continuous.

I’d be absolutely shocked if biological systems were somehow different.