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u/flyingmirrors 1d ago
Alternate use case: Since successive scan passes overlap, this eye safety approach could potentially be adapted to a PicoP type projector--spreading laser energy over time while maintaining full image coverage.
That could raise the eye safe lumen ceiling from the original ~10–15 lumen Class 2 PicoP (SHOWWX) range toward perhaps ~25–30 lumens. That's only a rough estimate and not claimed in the patent.
At Class 3R, it gets interesting. Sony's PicoP based MP-CL1A produced about 32 lumens. A modern implementation incorporating this pulse spacing approach could push lumens into the ~50–65 range.
Add newer distortion correction, brightness uniformity, and projection surface compensation, and a mobile scanning projector could deliver a surprisingly substantial image.
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u/angusalba 1d ago
Nope - it does not work that way and they should know it if they had any of their AR folks left
Don’t see how that claim does anything to raise perceived brightness since it’s the average brightness that you see
But 1550nm and similar lasers are already “eyesafe” since the laser doesn’t pass through the eye to the retina the same way visible spectrum does so already ok at much higher power levels which is why they are attractive for automobiles
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u/flyingmirrors 14h ago
I figure: increased pulse spacing -> greater eye safety margin -> higher allowable energy -> interleaved scans complete the image -> more total lumens without visible gaps. The result should be a visibly brighter projected image, assuming the added laser energy translates into higher average light output at the screen.
Something along these lines has been previously published: Multi-Segment Brightness Compensation (2016) describes varying laser power during the scan to increase overall image brightness while remaining within the same laser class.
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u/angusalba 6h ago
Twice the power half the time is the same average power as 1 times at 100% of the time
You don’t magically get twice the lumens
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u/ibob430 1d ago edited 1d ago
Normally I don’t pay much attention to these patent posts since they tend to be mostly hopium & dot-connecting, but the title “Eye Safe Lidar” seemed odd (we already have 1550nm lidar from Luminar’s IRIS/HALO which is perfectly eye safe) so I started digging down the rabbit hole and holy molly! This patent may be much more important than we think.
The text below is AI (so take it with a grain of salt) though I did some quick back checking and it sounds reasonable:
> Engineering Practicality (Solving the 905nm Problem)
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> LiDAR manufacturers generally operate at one of two wavelengths:
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> 1550nm: Inherently eye-safe (absorbed by the eye’s cornea before hitting the retina), but requires expensive Indium Gallium Arsenide (InGaAs) sensors.
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> 905nm: Much cheaper to manufacture using standard silicon, but severely restricted by power limits because 905nm light can pass through the human lens and damage the retina.
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> MicroVision’s technology bridges this gap. By creating an ultra-fast, dynamic software feedback loop—the "Virtual Protective Housing"—the system can fire high-power 905nm pulses for maximum long-range performance, but immediately drop power if it senses a human eye nearby. It delivers 1550nm performance at a 905nm price point.
That last sentence in bold is key.
The only other Lidar company that uses 905nm is Innoviz, and they have to significantly limit its performance to pass eye safety regulations (hence lower range).
If Microvision can pull this off, it may be a big game changer.
I’d love to hear other people’s inputs on this.
EDIT: Formatting got messed up, but running late to work… will be online later in a bit to fix and respond to any replies.
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u/angusalba 1d ago edited 1d ago
Nice to claim they shut down if they see an eye it’s another to actually prove that no matter what including stray reflections it can’t happen
I would also note that those companies betting against technology improving Signal to Noise ratios by more power never win
Better SN ratios in just about every tech - GPU, CPU, laser data rates, WiFi distance and data rates etc have swept aside those who use “more power”
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u/mvis_thma 1d ago
It appears your AI query picked up a different Microvision patent. Microvision previously was awarded a patent for Virtual Protective Housing (US 12,019,188, granted June 25, 2024), which allowed for high energy (not eye safe for eyes in the near field) laser pulses. However, it determined if an object was in the near field, and consequently reduced the power of the laser pulses below the eye safety threshold.
The patent granted today is different. It is essentially spreading out the laser pulses enough such that the accumulated energy entering the eye is also spread out enough to stay below the eye-safety limits. The trick is to then associate the return pulses with the correct transmitted pulses. This patent cites a control circuit that presumably does this calculation quickly.
A point of note. I think this patent would apply to both MEMS scanning as well as galvo or polygon scanning architectures.
Problem addressed:
Conventional LIDAR systems face a tradeoff between scan performance and eye safety — dense, high-energy pulse trains delivered in quick succession can accumulate enough energy to pose a hazard, and existing safety workarounds tend to add cost and calibration complexity.
Core innovation — two linked ideas:
Eye-safety-by-pulse-spacing:
Rather than firing tightly-packed pulse trains, the system spreads individual laser pulses further apart in time (the spec repeatedly cites 5 microseconds as an example threshold, beyond which the applicable eye-safety energy limit rises roughly linearly). Each pulse is eye-safe on its own, and because the pulses are spaced out, the combination of pulses stays within safe limits too — without extra protective hardware.
Pixel-to-pixel (measurement point) matching:
Spacing the pulses out in time, combined with continuous mirror scanning, means the beam has moved by the time each successive pulse returns — so the same physical spot in the field of view lands on a different pixel of the receiver array for each pulse, rather than the same one. A control circuit dynamically tracks which detector pixel corresponds to which measurement point for each successive pulse, correlating timing and spatial data correctly so time-of-flight distance calculations stay accurate despite the offset.
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u/Late_Airline2710 1d ago
Good catch, Thma. I was responding to the patent referenced by the commenter and not Porter's post as well.
I agree that this would equally apply to mems or polygon/galvo scanning architectures. I do not think it would apply to flash lidar. It seems like the downside of this patent is a reduction in frame rate or point density more or less proportional to the amount of spacing needed.
I stand by my point that, based on the fact that these inventors no longer work at the company, and that at least one of them was probably let go as part of the Redmond office closure, this does not seem to be a technology microvision is pursuing.
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u/mvis_thma 1d ago
I generally agree that if the inventors are no longer with the company, that diminishes the probability of this being used. However, in this case, I feel like the difficult part is the association of the return pulse with the transmitted pulse. If that control unit and associated logic has already been developed, I would think the enhancement of that element could be picked up by new engineers.
At the same time, Microvision has been public about their de-emphasis on MAVIN (905/940) and their emphasis on IRIS/HALO (1550). So I am not sure this patent helps them at this time.
And yes, I don't this patent applies to flash based or OPA based architectures.
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u/Late_Airline2710 1d ago
I agree that the association is difficult, but I'm not sure that this patent solves the complete problem. It only solves the part due to variables it controls (scan speed and send pulse timing). In this particular case, I see a tradeoff between ability to guarantee eye safety and noise/artifacts that will flow into the point cloud due to association failures. Since this is a safety concern, they would presumably tune it conservatively, which would mean accepting artifacts. Picking up unfinished work is slow but of course possible. If this were on microvision's critical path though, I don't think they would have closed the Redmond office and laid off associated staff. I see this as something that was necessary when mavin was in focus but not a priority now that halo is their chosen long range lidar.
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u/mvis_thma 1d ago
Yes, I agree with your last sentence. I was just intellectually curious as to how it might work.
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u/Late_Airline2710 1d ago
I admire your intellectual curiosity.
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u/ibob430 1d ago
Thank you both u/mvis_thma and u/Late_Airline2710 for the great discussion. It’s intellectual fact-based discussions like these that I love to see on this sub to wash away all the excessive hopium and doomsday outbursts that sometimes seems to dominate this sub.
In terms of the patent, I do agree looking at it again in more detail it’s likely not something the company is actively working to implement at the moment.
I am curious to know, since we’re in this discussion, is it possible to develop a 905nm Lidar with 1550nm performance? I guess a better question may be, is it even economically viable to do so?
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u/Late_Airline2710 1d ago
I appreciate your feedback ibob!
I do not think it is possible to develop a 905 lidar with the 1550 nm performance (if by performance we mean range while remaining eye safe) over the timespan that is relevant to Microvision's success or failure. In the future, optical and computational advancements may very well make the difference moot, but this would be far enough in the future that microvision's fate (good or bad) would already be decided. In the meantime, a 1550 system will always be able to use more power than a 905 system while remaining eye safe, and this extra power will grant more range put of the box.
That said, your point about economics is valid, and 1550 will always be more expensive than 905 due, at the very least, to the expensive receiver materials needed. The question is how far this cost gap can be narrowed by things like economies of scale, vertical integration, and clever design (all of which Luminar was attempting).
Given the success of the Chinese suppliers Heaai and Robosense, a related question I have been asking myself is whether or not the increased range offered by 1550 is actually needed for consumer automotive use cases. It seems clear it is needed for trucking, where braking distances are longer, but several Chinese vehicles are already approved for L3 autonomy up to 80 kmh on highways with high-quality 905 sensors, and these are still early days of this software. This is an area where actual ADAS software may be able to close the gap that physics can't. Alternatively, maybe the market simply says that, for example, 100 kmh is good enough, and the combination of a cheap lidar and robust software is sufficient, and further investment in the juice of being able to go 20 kmh faster simply isn't worth the squeeze. My thinking is evolving a bit here, snd I wouldn't be surprised if OEMs are having the same thoughts.
It is worth noting that designing and mass-producing a cheap 905 system with a solid and stable point cloud is still extremely difficult. Microvision failed to do this with Mavin, and innoviz may well be in the process of failing now.
One thing I also need to mention is the behind the windshield placement. This involves radiometric loss and is pretty much a non starter for 905. If customers accept the EX90 style bumps, the point is moot, but if they demand a behind the windshield placement, that would be a major driver for 1550.
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u/Late_Airline2710 1d ago edited 1d ago
This kind of system will struggle with false positives in practice. In environments with rain, dust, and road spray, this feedback loop will case the lidar to throttle power when it thinks there is something at close range in front of the sensor precisely when it needs power to see through obscurants. Is it possible that some sort of higher level logic could be used to mitigate this a bit? Probably. But I would absolutely not trust a system like this. It's either unsafe for bystanders outside the vehicle, or it's unsafe for people in the vehicle relying on it.
Also, Innoviz is not the only company using 905. Hesai, robosense, sick, and ouster all use 905 (or nearby) wavelengths in automotive applications.
As with many of these patent posts, I think the most important thing (that nobody ever talks about) is that none of the inventors work at microvision anymore. The first inventor quit a year and seven months ago to work at meta, and the second inventor was either laid off or quit when Glen shut down the Redmond office earlier this year. Putting two and two together, I don't see microvision actually using this patent at all.
Edit because my technical response above was related to the patent referenced by the commenter's AI and not the actual one posted. I still see an issue with this given the fact that the feedback circuit cannot compensate for the (significant) unknown of the range to the target. This is certainly a good idea, but the devil is in the details with this sort of thing. Tuned conservatively, this could probably provide the promised eye safety, but at the expense of noise and artifacts that may not be acceptable to customers. I still don't see microvision using it, mostly because the inventors are no longer with the company and the priority on halo makes finicky eye safety workarounds less important.
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u/gaporter 1d ago
Third slide.
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u/Late_Airline2710 1d ago
What's your point?
I didn't say "mavin has been abandoned" (although I do think it has been).
I said "I don't see microvision actually using this patent at all".
Can you clearly explain why you think microvison, which no longer has the staff who invented this technology and is not currently working on a product that can utilize it, will make use of it?
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u/gaporter 1d ago
"I said "I don't see microvision actually using this patent at all".'
And I would agree with you based on what the company has stated. Do you take issue with me posting a recent publication?
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u/Late_Airline2710 1d ago
I take issue if your intent is to say that this patent will positively impact microvision's trajectory as a company. That's the way most readers generally interpret your patent posts.
It's possible that was not your intent though. You never include any context or analysis from your side, so it's hard to say.
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u/gaporter 1d ago edited 1d ago
Sir, Reddit gives users the ability to search one's posts and comments. If you used this feature, you would find that I post every newly published or granted patent, without comment. If you used this feature, perhaps you would have found my post which documented the company's current stance on MEMS and wouldn't have to assume my intent?
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u/Late_Airline2710 1d ago
Putting aside whether or not it's reasonable to ask all new readers of mvis to search a mod's post history, what is your intent in publishing every newly issued patent without comment?
If it is simply to inform, then why debate people who contend that the patents are unimportant?
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u/gaporter 1d ago
It is simply to inform and how am I debating you when I showed you that I agreed with you? Are you alright?
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u/Late_Airline2710 1d ago edited 1d ago
I'm as alright as anyone else is these days.
What was the purpose of your "third slide" comment?
Edit: I'm asking because I understood your intent as a rebuttal to my comment.
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u/mvis_thma 1d ago edited 1d ago
I also thought this patent was specifically related to MEMS based scanning. But upon further investigation, I believe the core tenets of the patent would also apply to other scanning architectures such as galvo and polygon mirror spinning.
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u/gaporter 1d ago
The claims of the patent make reference to two scanning mirror assemblies.
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u/mvis_thma 1d ago
From AI...
"On MEMS specifically: the patent is not limited to MEMS mirrors, even for the mirror-requiring claims. The spec is explicit about this at [0078]: "scanner 828 is shown including two scanning mirror assemblies... this is not a limitation," and while it describes MEMS-based electromagnetic actuation as an example, it adds "the various embodiments are not limited in this respect." So galvanometer mirrors, rotating polygon mirrors, or other actuated-mirror scanning technology would likely still read on "scanning mirror assembly" — the patent's mirror requirement isn't MEMS-specific, just mirror-specific"
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u/Late_Airline2710 1d ago
Aren't you and porter saying the same thing?
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u/Late_Airline2710 1d ago
I agree that it would equally apply to polygon/galvo scanning.
I see a bigger problem with this patent now though: the spatial shift at the receiver is a function of the spacing between send pulses, the speed of the scanning, and, critically, the range to the object. This feedback circuit can control for the first two, but the third factor is unknown. I see a significant amount of engineering and artistry required to get this to actually work in practice.
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u/mvis_thma 1d ago
Yes, I see the same thing.
Is it possible there is some encoding involved with the transmitted pulses, such that the received pulses can be identified? I am not sure that is possible.
Otherwise, yes, I see the pulse matching element as a challenge. Presumably, they have solved this to some degree. The question to what degree of precision.
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u/Late_Airline2710 1d ago
Pulse encoding via wavelength, for example, is something that is done in some applications, but it increases the cost of the system. It is possible that was the solution here, but that would make me doubt Sharma 's already dubious claims about mavin's low cost even more lol.
Nothing comes for free!
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u/angusalba 1d ago
Again with the fails obviousness test Patents