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)
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
> 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.
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?
> Additionally, no LIDAR manufacturer publishes beam-failure shutoff latency. Most are >50ms, which can be long enough for permanent injury
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).
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.
the hurdle to full autonomous driving was basically jumped by Tesla this year.
It's not nothing, but it's a long way from being a complete system (let alone the obviously superior one).
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.
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.
Baraja selling point was AFAIK that they used a integrated swept laser source (they typically have lower coherence but you can work around that in DSP).
Why can't you place them further away from each other using an additional optical system (i.e. a mirror) and adjusting for the additional distance in software?
Edit: There's basically three approaches to this problem that I'm aware of. Number one is to push the cross-talk below the noise floor -- your suggestion helps with this. Number two is to do noise cancellation by measuring your cross-talk and deleting it from the signal. Number three is to make the cross-talk signal distinct from a real reflection (e.g. by modulating the pulses so that there's low correlation between an in-flight pulse and a being-fired pulse). In practice, all three work nicely together; getting the cross-talk noise below saturation allows cancellation to leave the signal in place, and reduced correlation means that the imperfections of the cancellation still get cleaned up later in the pipeline.
But humans have no lidar technology. We rely almost solely on sight for driving (and a tiny bit on sound I guess). Hence in principle it should be possible for cars to do so too. My question is this: at what point, if at all, will self-driving get good enough to make automotive lidar redundant? Or will it always be able to make the self-driving 1% better than just cameras?
As far as Tesla, time will tell. I ride their robotaxis daily and see them performing better than Waymo, but it's obviously meaningless until we see accident stats after they remove safety monitors.
I've seen this claimed a lot but never have gotten a definitive answer.
Is this like "overall better but hard to pinpoint" or "this maneuver is smoother than Waymo" or something in between?
Would love to hear experiences with them since they're so limited currently.
By 2018, if you listen to certain circa-2015 full self-driving technologists.
And it is certain that in India they use sound sound for echolocation.
Agreed, but there are still really good human drivers, who still operate on sight alone. It's more about the upper bound, not the human average, that can be achieved with only sight.
The second and third place companies in terms of the number of deployed robotaxis are both subsidiaries of large Chinese Internet platforms, and both of them are also leaders in providing geospatial data and navigation in China. Neither operates camera-only vehicles.
Interference between LIDARs can be a problem, mostly with the continuous-wave emitters. Pulsed emitters are unlikely to collide in time, especially if you put some random jitter in the pulse timing to prevent it. The radar people figured this out decades ago.
For pulsed emitters, indeed adding random jitter in the timing would avoid the problem of multiple lidars being synced up and firing at the same time. For some SPAD sensors, it's common to emit a train of multiple pulses to make a single measurement. Adding random jitter between them is a known and useful trick to mitigate interference. But in fact it isn't super accurate to say that interference is a problem for continuous-wave emitters either. Coherent FMCW lidar are typically quite robust against interference by, say, using randomized chirp patterns.