Anti-limelight glasses for drive team?

That is why LRIs get paid the big bucks and high percentage bonuses. :slight_smile:


We lit up the retroreflector with a 3.7W, 850nm flashlight this evening, but the limelight camera couldn’t see it at all. :upside_down_face:

Not sure you want to dive into it, but there may be a filter you could remove to let that wavelength through. Also, eye safety is critical with IR emitters, since you don’t have the blink response eye damage is much more likely. In addition, different parts of the eye absorb or transmit IR light at different wavelengths which is also a critical factor on having a safe system.


Nate, you can adjust the thresholding settings to track 850nM no problem. One of our PNW teams had a prototype limelight with red LEDs just for fun.

While 850 nm is in the near infrared range and our LEDs were red so these aren’t very comparable, we were able to track the tape just fine with a different color.


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Right-- the problem statement was:

Compared with past years, the 2020 game poses a greater [1][2] operational risk that teams choosing to target the retroreflector with bright, visible lights will be prevented from doing so due to a concern about the safety of that light exposure (intensity * duration).

[1] The goal is located above the opposing alliance’s driver station.
[2] It is reasonable for an alliance to be attempting shots throughout most of the match.

If IR is no safer than visible light, then it isn’t a solution to the problem statement.


A little bit off topic. But. We use distance measuring lasers at work for positioning. Most of them are red. Completely safe to look at at normal distances. No immediate danger even looking straight into them from short distances. One of the lasers is IR (You don’t see it in operation and you have to turn on the marking laser to aim it). While we didn’t buy for this feature, one of the reasons for it being that way is because of complaints that the “red laser” was harmful to eyes. In this case the IR laser is no more or less dangerous but did not generate complaints from employees.

More on topic: To be honest risk to eyes should be of highest concern. Losing the use of them is to say the least life changing. At what point the lights become a risk should not be left to judgement of random RIs, Referees, or game design committees. First really should have some one competent in this area to do a real risk analysis. That would provide a real basis for what is just annoying or distracting and what is a real risk. Often very different things.

Edit: To fair to First: They may have already considered this and have done the appropriate risk analysis.


Tinting the windows has been brought up before, can FIRST tint them?

If only there were robotics competitions out there that have vision based challenges that don’t rely on retroreflective tape and bright lights… hmm, if only there were examples we could find out in the wild.

In all seriousness, I do wonder if the wheel of fortune isn’t an attempt to gauge if teams can do vision without lights this year.

In all reality, if someone wants to find anti green wavelength glasses, they need to make sure it meets Z87 and Z136. I’ve found some at if anyone really wants them. I’m not convinced they are actually needed though.

To be honest, I think most of the targeting lights use fall into the category of distracting or irritating rather than harmful. But I not really qualified to make that judgement. Tinting the driver station windows would hurt vision across the field and do nothing for the field people not behind the driver stations

I can’t remember where I got them, but I have a pair of 532 nm safety rated laser glasses that I would look into. You shouldn’t be that impaired by the limelight though.

ok so this might just be me not understanding how light works but if we had driver station glass that blocked green light wouldn’t it just make that light not green but still as bright

You are correct. It would block it for the drive team, but others not.

so there would still be a really bright light where the limelight is pointing it just wouldn’t be green right

I went and bought these cheap $7 glasses, I will say they work surprisingly well. The LEDs are reduced to the brightness of indicator lights, you can tell they’re on but it’s not harsh at all. Only downsides are that they’re only easily worn by people with good eyesight (because optical glasses, safety glasses, and laser classes all together proves to be a bit too much), and that everything is tinted red. Red vs Blue bumpers are still easy to differentiate though so while not ideal I think it will serve as a backup plan should it become a problem in competition. They’re also somewhat reflective so the opposing alliance might get a bit of a light-show, but if they’re ok shining us with it then they must be ok with it pointed at them too.

Don’t take my word for this:
I’d think that the light is still seen from the field side, but the alliance station side shouldn’t see it. My thinking- kind of like a bulletproof window, the bullet hits one side but doesn’t go through the other.

Edit: anti blue light glasses block blue light from reaching the eyes. You still see the blue dot on the outside of the lens but it is a lot dimmer than a regular lens.

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Anyone think about requiring polarization of the light so then you can polarize the driver station in the opposite direction and the light is gone from the drivers. (although if you add another filter in the middle you get brighter because light is weird)

It seems like the limelight could be re-outfitted with Infrared LEDs instead of Green to make it 100% less blinding. I’m curious FRC hasn’t made any moves about this.

Only because not all of the light coming from a green LED is green. It would cut the overall intensity way down because you’d not be getting any of the green hitting your eyes, just the other, non-filtered colors.

If you’d like to learn more:

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