6 ms·

Adding a comment here with some info on LIDAR human safety, since many are asking. There are two wavelengths of interest used: a) 905 nm/940 nm (roof and bu

Adding a comment here with some info on LIDAR human safety, since many are asking. There are two wavelengths of interest used: a) 905 nm/940 nm (roof and bumpers): 70–100 µJ per pulse max, regulated by IEC 60825 since this WL is focused on the retina b) 1550 nm systems (the Laser Bear Honeycomb): 8–12 mJ per pulse allowed (100x more photons since this WL stays the cornea) The failure mode of these LIDARs can be akin to a weapon. A stuck mirror or frozen phased array turns into a continuous-wave pencil beam. A 1550 nm LIDAR leaking 1W continuous will raise corneal temperature >5C in 100ms. The threshold for cataract creation is only 4C rise in temp. A 905 nm Class 1 system stuck in one pixel gives 10 mW continuous on retina, capable of creating a lesion in 250ms or less. 20 cars at an intersection = 20 overlapping scanners, meaning even if each meets single-device Class 1, linear addition could offer your retina a 20x dose enough to push into Class 3B territory. The current regs (IEC 60825-1:2014) assume single-source exposure. There is no standard for multi-source, multi-axis, moving-platform overlay. Additionally, no LIDAR manufacturer publishes beam-failure shutoff latency. Most are >50ms, which can be long enough for permanent injury

addaon 11mo ago
> There are two wavelengths of interest used Ouster uses (or at least used to use, not sure if they still do) 840 nm. Much higher quantum efficiency for standard silicon receivers, without having to play games with stressed silicon and stuff; but also much better focusing by the retina, so lower power permitted.
krackers 11mo ago
I was always curious about this, it's impossible to find any safety certifications or details about the lidars used by e.g. Waymo. Are we supposed to just trust that they didn't cut corners, especially given the financial incentives to convince people that lidar is necessary (because there's a notable competitor that doesn't use it). To date most class-1 lasers have also been hidden/enclosed I think (and there is class 1M for limited medical use), so I'm not convinced that the limits for long-term daily exposure have been properly studied. Until I see 3rd party studies otherwise, I plan to treat vehicle lidar no different than laser pointers and avoid looking directly at them. If/when cars become common enough that this is too hard to do, maybe I'll purchase NIR blocking glasses (though most ones I found have an ugly green tint, I wonder if it's possible to make the frequency cutoff sharp enough that it doesn't filter out visible reds).
- Zigurd 11mo ago
  Every day dozens of Waymos are in close proximity to the people cleaning them and plugging them in, and they are maneuvering in tight spaces amongst other Waymos. That's not a peer reviewed study, but it seems to work.
  - denkmoon 11mo ago
    Workplace injuries have never been swept under the rug, especially if those cleaners are non-persons in the eyes of the government.
    - Zigurd 11mo ago
      That's a possibility. Google appears to be contracting out depot work to car rental companies because a Waymo depot is basically a car rental lot. They need three shifts for each depot. So there's probably a couple hundred people who would otherwise be cleaning out rental cars working the depots. At some point injuries would get hard to sweep under the rug.
  - smallmancontrov 11mo ago
    The fried iPhone pixels are spooky. Eyes clearly aren't as affected, but they also aren't as easy to replace.
    - CGMthrowaway 11mo ago
      A camera CMOS dies at 1–2 µJ pulse, this same pulse energy reaches the cornea. If a sensor has fried, that means the dose to your eye is already in the zone of cataract creation. Human corneal endothelial cells do not regenerate. If the endothelium is damaged, stromal fluid accumulates and opacity can progressively over months/a year from one hit. You might never know what caused it.
  - krackers 11mo ago
    The visual system can patch over tiny defects (see: blindspot) and visual field tests have not been part of standard yearly eye exams I've been to. And possible longer-term risks (say increased risk of cataracts) would be harder to conclusively show. And the sample size involved would skew heavily towards young healthy adults instead of people with pre-existing eye conditions. I realize it's not easily possible to prove the negative, but when you're exposing the public the burden must be on the company to be transparent and rigorous. And from what I see it's difficult to even find certification documents for the lidars used in commercial self-driving vehicles, possibly because everything is proprietary and trade secret.
addaon 11mo ago
A quick note about units -- you correctly quote the limits as an energy-per-pulse limit. The theory behind this is that pulses are short enough that rotation during a pulse is negligible, so they tend to hit a single point (on the retina, at focusable frequencies; the cornea itself for longer wave lengths), and the absorption of that energy is what causes damage. But LiDAR range is determined not by energy per pulse, but by power. This drives a desire for minimum-time pulses, often < 10 ns -- if you can halve your pulse length, you can increase your range substantially while still being eye-safe. GaNFETs are one of the enabling technologies for pulsed lidar, since they're really the only way out there to steer tens of amps in single-digit nanoseconds. Even once you've solved generating short pulses, though, you still need to interpret short responses. Which drives either a need for very fast ADCs (gigasample+), or TDCs, which are themselves fascinating components.
dllu 11mo ago
The article talks about eye safety a bit in section 4. > a stuck mirror This is one of the advantages of using an array of low power lasers rather than steering a single high power laser. The array physically doesn't have a failure mode where the power gets concentrated in a single direction. Anyway, theoretically, you would hope that class 1 eye-safe lidars should be eye safe even at point blank range, meaning that even if the beam gets stuck pointing into your eye, it would still be more or less safe. > 20 cars at an intersection = 20 overlapping scanners, meaning even if each meets single-device Class 1, linear addition could offer your retina a 20x dose enough to push into Class 3B territory. In the article, I point out a small nuance: If you have many lidars around, the beams from each 905 nm lidar will be focused to a different spot on your retina, and you are no worse off than if there was a single lidar. But if there are many 1550 nm lidars around, their beams will have a cumulative effect at heating up your cornea, potentially exceeding the safety threshold. Also, if a lidar is eye-safe at point blank range, when you have multiple cars tens of meters away, laser beam divergence already starts to reduce the intensity, not to mention that when the lidars are scanning properly, the probability of all of them pointing in the same spot is almost impossible. By the way, the Waymo Laser Bear Honeycomb is the bumper lidar (940 nm iirc) and not the big 1550 nm unit that was on the Chrysler Pacificas. The newer Jaguar I-Pace cars don't have the 1550 nm lidar at all but have a much bigger and higher performance spinning lidar.
- ErroneousBosh 11mo ago
  > > a stuck mirror Detect the mirror being stuck and shut the beam off. Easy. Hint: how bad would it be if the MCU in your gas heating boiler latched up and wouldn't shut the burner off? How is this mitigated?
  - marcellus23 11mo ago
    This was addressed in the original comment: > Additionally, no LIDAR manufacturer publishes beam-failure shutoff latency. Most are >50ms, which can be long enough for permanent injury
    - 11mo ago
observationist 11mo ago
Enormous complexity, safety risks, and completely unnecessary for successful level 4 FSD - the hurdle to full autonomous driving was basically jumped by Tesla this year. I don't see why lidar is even allowed in public at this point, it seems dangerous enough that you'd want it effectively restricted to highly regulated and licensed uses, like military or academic scanning, with all sorts of deliberate safeguards and liability checks. Social media is full of little clips of lidar systems burning out camera pixels, and I'm sure big proponents of the tech have paid people off over eye injuries at this point. There've probably been a ton of injuries that just got written off as random environmental hazards, "must have looked at the sun" etc. It's nuts that this stuff gets deployed.
- AlotOfReading 11mo ago
  the hurdle to full autonomous driving was basically jumped by Tesla this year. Tesla doesn't have driverless operations anywhere, and their Austin fleet consists of <30 vehicles with full time safety drivers that have a far worse safety record than Waymo vehicles. It's not nothing, but it's a long way from being a complete system (let alone the obviously superior one).
  - vardump 11mo ago
    IIRC, Tesla's safety record is about 30% worse than Waymo. The gap has been closing rapidly. It's not that long time ago Tesla made an order of magnitude more mistakes than Waymo.
    - AlotOfReading 11mo ago
      That's with safety drivers, a small fleet, and literally only the most recent data (since it wasn't broken out before). My experience with AV deployments is that your incident rate is significantly different once you remove humans, and small fleet sizes/deployment areas hide a lot of long tail issues. Waymo is operating at a much larger scale across a huge range of conditions with hardware that's generations behind their latest and still performing better.
et-al 11mo ago
Yeah, I was surprised stories of Volvo's EX90 lidar damaging camera sensors didn't get more traction: https://www.thedrive.com/news/volvo-ex90s-lidar-sensor-will-fry-your-phones-camera https://www.thedrive.com/news/volvo-ex90s-lidar-sensor-will-... One would hope there would be more regulation around this.
- tkfoss 11mo ago
  I'm not surprised at all. This is not new - Jan 2019 https://image-sensors-world.blogspot.com/2019/01/1550nm-lidar-damages-sony-camera-at-ces.html https://image-sensors-world.blogspot.com/2019/01/1550nm-lida... Just look at the comments of article you posted, with sock puppet accounts being actively hostile towards anyone asking questions.
neilv 11mo ago
I live in town, and walk past countless stopped and moving cars every day. I also know how the tech industry makes decisions about safety and responsibility (hahaha...). And I have seen some of the recent changes that automakers have somehow slipped past safety regulators. So it seems foolish to trust any of them on this safety issue. Do we all have to move to rural areas, if we want to be able to go outside without wearing laser safety goggles?
- colechristensen 11mo ago
  Time to make a sunglasses and window tint company specifically formulating their products to shield from these kinds of lasers.
  - krackers 11mo ago
    If you find anything, please let me know. The least obtrusive option I've found is this Zeiss lens coating ("Thermo Force") which claims to block 90% of IR "between 780 and 2000 nm", which covers the NIR used in both types of lidar. It only seems to be available as part of sunglasses though.
    - addaon 11mo ago
      Laser safety glasses are off-the-shelf, but are usually tuned for a single band stop. There are at least three frequencies of near IR LiDAR in use in the wild.
      - krackers 11mo ago
        Hm the ones I can find have a heavy green reflex and their optical density seems about twice or thrice what you'd need for a 1W CW laser. Maybe it's unavoidable given the closeness of near IR and deep red, but I wonder if there exists glasses with a cutoff sharp enough and reduced OD so as to not result in noticeable color shift.
        11mo ago
appreciatorBus 11mo ago
The incredible irony that reduced injury and death from collisions is how these things are sold to registers and cities, but no one mentioned that in a city full of millions of poorly maintained lidars, they just might slowly make everyone blind instead.

addaon 11mo ago

> There are two wavelengths of interest used Ouster uses (or at least used to use, not sure if they still do) 840 nm. Much higher quantum efficiency for standard silicon receivers, without having to play games with stressed silicon and stuff; but also much better focusing by the retina, so lower power permitted.

krackers 11mo ago

I was always curious about this, it's impossible to find any safety certifications or details about the lidars used by e.g. Waymo. Are we supposed to just trust that they didn't cut corners, especially given the financial incentives to convince people that lidar is necessary (because there's a notable competitor that doesn't use it). To date most class-1 lasers have also been hidden/enclosed I think (and there is class 1M for limited medical use), so I'm not convinced that the limits for long-term daily exposure have been properly studied. Until I see 3rd party studies otherwise, I plan to treat vehicle lidar no different than laser pointers and avoid looking directly at them. If/when cars become common enough that this is too hard to do, maybe I'll purchase NIR blocking glasses (though most ones I found have an ugly green tint, I wonder if it's possible to make the frequency cutoff sharp enough that it doesn't filter out visible reds).

Zigurd 11mo ago
Every day dozens of Waymos are in close proximity to the people cleaning them and plugging them in, and they are maneuvering in tight spaces amongst other Waymos. That's not a peer reviewed study, but it seems to work.
- denkmoon 11mo ago
  Workplace injuries have never been swept under the rug, especially if those cleaners are non-persons in the eyes of the government.
  - Zigurd 11mo ago
    That's a possibility. Google appears to be contracting out depot work to car rental companies because a Waymo depot is basically a car rental lot. They need three shifts for each depot. So there's probably a couple hundred people who would otherwise be cleaning out rental cars working the depots. At some point injuries would get hard to sweep under the rug.
- smallmancontrov 11mo ago
  The fried iPhone pixels are spooky. Eyes clearly aren't as affected, but they also aren't as easy to replace.
  - CGMthrowaway 11mo ago
    A camera CMOS dies at 1–2 µJ pulse, this same pulse energy reaches the cornea. If a sensor has fried, that means the dose to your eye is already in the zone of cataract creation. Human corneal endothelial cells do not regenerate. If the endothelium is damaged, stromal fluid accumulates and opacity can progressively over months/a year from one hit. You might never know what caused it.
- krackers 11mo ago
  The visual system can patch over tiny defects (see: blindspot) and visual field tests have not been part of standard yearly eye exams I've been to. And possible longer-term risks (say increased risk of cataracts) would be harder to conclusively show. And the sample size involved would skew heavily towards young healthy adults instead of people with pre-existing eye conditions. I realize it's not easily possible to prove the negative, but when you're exposing the public the burden must be on the company to be transparent and rigorous. And from what I see it's difficult to even find certification documents for the lidars used in commercial self-driving vehicles, possibly because everything is proprietary and trade secret.

addaon 11mo ago

A quick note about units -- you correctly quote the limits as an energy-per-pulse limit. The theory behind this is that pulses are short enough that rotation during a pulse is negligible, so they tend to hit a single point (on the retina, at focusable frequencies; the cornea itself for longer wave lengths), and the absorption of that energy is what causes damage. But LiDAR range is determined not by energy per pulse, but by power. This drives a desire for minimum-time pulses, often < 10 ns -- if you can halve your pulse length, you can increase your range substantially while still being eye-safe. GaNFETs are one of the enabling technologies for pulsed lidar, since they're really the only way out there to steer tens of amps in single-digit nanoseconds. Even once you've solved generating short pulses, though, you still need to interpret short responses. Which drives either a need for very fast ADCs (gigasample+), or TDCs, which are themselves fascinating components.

dllu 11mo ago

The article talks about eye safety a bit in section 4. > a stuck mirror This is one of the advantages of using an array of low power lasers rather than steering a single high power laser. The array physically doesn't have a failure mode where the power gets concentrated in a single direction. Anyway, theoretically, you would hope that class 1 eye-safe lidars should be eye safe even at point blank range, meaning that even if the beam gets stuck pointing into your eye, it would still be more or less safe. > 20 cars at an intersection = 20 overlapping scanners, meaning even if each meets single-device Class 1, linear addition could offer your retina a 20x dose enough to push into Class 3B territory. In the article, I point out a small nuance: If you have many lidars around, the beams from each 905 nm lidar will be focused to a different spot on your retina, and you are no worse off than if there was a single lidar. But if there are many 1550 nm lidars around, their beams will have a cumulative effect at heating up your cornea, potentially exceeding the safety threshold. Also, if a lidar is eye-safe at point blank range, when you have multiple cars tens of meters away, laser beam divergence already starts to reduce the intensity, not to mention that when the lidars are scanning properly, the probability of all of them pointing in the same spot is almost impossible. By the way, the Waymo Laser Bear Honeycomb is the bumper lidar (940 nm iirc) and not the big 1550 nm unit that was on the Chrysler Pacificas. The newer Jaguar I-Pace cars don't have the 1550 nm lidar at all but have a much bigger and higher performance spinning lidar.

ErroneousBosh 11mo ago
> > a stuck mirror Detect the mirror being stuck and shut the beam off. Easy. Hint: how bad would it be if the MCU in your gas heating boiler latched up and wouldn't shut the burner off? How is this mitigated?
- marcellus23 11mo ago
  This was addressed in the original comment: > Additionally, no LIDAR manufacturer publishes beam-failure shutoff latency. Most are >50ms, which can be long enough for permanent injury
  - 11mo ago

observationist 11mo ago

Enormous complexity, safety risks, and completely unnecessary for successful level 4 FSD - the hurdle to full autonomous driving was basically jumped by Tesla this year. I don't see why lidar is even allowed in public at this point, it seems dangerous enough that you'd want it effectively restricted to highly regulated and licensed uses, like military or academic scanning, with all sorts of deliberate safeguards and liability checks. Social media is full of little clips of lidar systems burning out camera pixels, and I'm sure big proponents of the tech have paid people off over eye injuries at this point. There've probably been a ton of injuries that just got written off as random environmental hazards, "must have looked at the sun" etc. It's nuts that this stuff gets deployed.

AlotOfReading 11mo ago
the hurdle to full autonomous driving was basically jumped by Tesla this year. Tesla doesn't have driverless operations anywhere, and their Austin fleet consists of <30 vehicles with full time safety drivers that have a far worse safety record than Waymo vehicles. It's not nothing, but it's a long way from being a complete system (let alone the obviously superior one).
- vardump 11mo ago
  IIRC, Tesla's safety record is about 30% worse than Waymo. The gap has been closing rapidly. It's not that long time ago Tesla made an order of magnitude more mistakes than Waymo.
  - AlotOfReading 11mo ago
    That's with safety drivers, a small fleet, and literally only the most recent data (since it wasn't broken out before). My experience with AV deployments is that your incident rate is significantly different once you remove humans, and small fleet sizes/deployment areas hide a lot of long tail issues. Waymo is operating at a much larger scale across a huge range of conditions with hardware that's generations behind their latest and still performing better.

et-al 11mo ago

Yeah, I was surprised stories of Volvo's EX90 lidar damaging camera sensors didn't get more traction: https://www.thedrive.com/news/volvo-ex90s-lidar-sensor-will-fry-your-phones-camera https://www.thedrive.com/news/volvo-ex90s-lidar-sensor-will-... One would hope there would be more regulation around this.

tkfoss 11mo ago
I'm not surprised at all. This is not new - Jan 2019 https://image-sensors-world.blogspot.com/2019/01/1550nm-lidar-damages-sony-camera-at-ces.html https://image-sensors-world.blogspot.com/2019/01/1550nm-lida... Just look at the comments of article you posted, with sock puppet accounts being actively hostile towards anyone asking questions.

neilv 11mo ago

I live in town, and walk past countless stopped and moving cars every day. I also know how the tech industry makes decisions about safety and responsibility (hahaha...). And I have seen some of the recent changes that automakers have somehow slipped past safety regulators. So it seems foolish to trust any of them on this safety issue. Do we all have to move to rural areas, if we want to be able to go outside without wearing laser safety goggles?

colechristensen 11mo ago
Time to make a sunglasses and window tint company specifically formulating their products to shield from these kinds of lasers.
- krackers 11mo ago
  If you find anything, please let me know. The least obtrusive option I've found is this Zeiss lens coating ("Thermo Force") which claims to block 90% of IR "between 780 and 2000 nm", which covers the NIR used in both types of lidar. It only seems to be available as part of sunglasses though.
  - addaon 11mo ago
    Laser safety glasses are off-the-shelf, but are usually tuned for a single band stop. There are at least three frequencies of near IR LiDAR in use in the wild.
    - krackers 11mo ago
      Hm the ones I can find have a heavy green reflex and their optical density seems about twice or thrice what you'd need for a 1W CW laser. Maybe it's unavoidable given the closeness of near IR and deep red, but I wonder if there exists glasses with a cutoff sharp enough and reduced OD so as to not result in noticeable color shift.
      - 11mo ago

appreciatorBus 11mo ago

The incredible irony that reduced injury and death from collisions is how these things are sold to registers and cities, but no one mentioned that in a city full of millions of poorly maintained lidars, they just might slowly make everyone blind instead.