useing UV

[drakesword]

Haven't found it anywhere in the rules but would the use of UV light be legal?

Were thinking of 2 or 3 LEDs. I know that UV shows up VERY well on camera(to the point that it could saturate the image)

[samir13k]

I believe you're thinking of IR and i dont see why not, but im not the rule book

[Tristan Lall]

Ultraviolet LEDs aren't such a great idea: many are of a wavelength and intensity that can be harmful with direct exposure, and since the human eye's blink reflex doesn't work on UV, you don't really know when you're being exposed. They're not illegal, but they would be subject to the usual safety rules.

As for infrared—which does show up on CCD cameras—it's allowed. (Infrared at an intensity high enough to harm you would be something to behold...if only you could see it.)

And by the way, <R02> says you can't include anything intended to interfere with other robots' vision systems. <G30> says you get a red card if you try.

[DonRotolo]

3 or 4 watts is enough to hurt you. The iris of the human eye does not have a response to IR like it does to visible light. But you won't see that kind of light with an LED...

[drakesword]

I was thinking with the power output of the LED at a great distance as the robot to the judges/spectators it shouldn't be a problem. Doesn't plexi block uv?

[Al Skierkiewicz]

Bryant,
You are sitting right next to it in the pit, while working on it at home and you are exposing everyone that the robot drives by during a match. That is, field resetters, refs, FTA, FTAA, judges, and me. There is a reason those guys on CSI and at the dentist office wear special glasses. Please re-engineer to use something other than UV radiating devices.

[EricH]

Originally Posted by Tristan Lall

And by the way, <R02> says you can't include anything intended to interfere with other robots' vision systems. <G30> says you get a red card if you try.

<R02> also says that "ROBOT parts shall not be made from hazardous materials, be unsafe, or cause an unsafe condition. Items specifically prohibited from use on the ROBOT include (but are not limited to): [list]". If in the judgment of the inspectors, refs, and other similar field personnel, your robot is doing any of the above, you will be found in violation of <R02>, regardless of any of the specific points not covering it.

And Al is an inspector.

[drakesword]

I gotcha. I'm not saying we are using it just trying to find out if it was an option. I know UV at certain levels or high enough wavelengths could be dangerous but didn't know if 1 or 2 leds of the near uv would be bad. Seeing as it is questionable we will stay away from it.

I have asked a couple of the local inspectors this past weekend who gave answers of being unknown. (actually one said he didn't see it as being an issue)

So for an alternative we shall look at a large number of red and blue leds.

[Al Skierkiewicz]

Bryant,
I suspect that the inspectors you talked with were unaware of the issues. Most people are not familiar with UV radiation and it's effects. It is not something that we have discussed in inspector training.
There are LEDs and then there are LEDs. Since we can't see the radiation, we can't tell if they are super bright or merely bright.

[Alan Anderson]

Originally Posted by drakesword

So for an alternative we shall look at a large number of red and blue leds.

What do you intend to do with these LEDs?

If they are to be used as illumination for the retroreflective tape, keep in mind that you probably don't want to make it very bright. The tape itself is extremely reflective. A too-bright light will completely saturate the camera, which will keep you from being able to match a particular color.

Our testing gives us useful results from a dozen semi-bright red LEDs behind a layer of mylar used as a diffuser. We're going to try again with (less-bright) green ones, because using a red color target we've seen undesired recognition of robot bumpers.

[drakesword]

@alan

We were going to use maybe 12-18 half and half.

Turn brightness down to 0, white balance off and only go for the bright spots.

From the bright spots filter out anything other then purple.


@al
Just curious. Does blacklight not constitute as near UV? Not to sound like a jerk but blacklights have typically been deemed safe as far as UV exposure went although still having the effects of such (e.g. phosphorescence)

[Al Skierkiewicz]

Yes, blacklights are UV but they produce very little when in use. Since they are not a point source, the energy is spread out and some of it is visible. The UV source for erasing EPROMs is a higher energy and it is protected so that you cannot be in the radiation. Remember that tanning salons (tanning tables) require that you wear eye protection and that is also UV in nature.

[drakesword]

Originally Posted by Al Skierkiewicz

Yes, blacklights are UV but they produce very little when in use. Since they are not a point source, the energy is spread out and some of it is visible. The UV source for erasing EPROMs is a higher energy and it is protected so that you cannot be in the radiation. Remember that tanning salons (tanning tables) require that you wear eye protection and that is also UV in nature.

Not to drag this on or anything but if we were to say diffuse 2 leds with the same wavelength or longer through a tube would you have an issue with it or is it still too questionable.

I understand the dangers with shorter wavelengths or a point source but for near UV at low power diffused like a blacklight I don't see the issue.

[Al Skierkiewicz]

Bryant,
We are answering in more general terms because the original post doesn't specify output power, output spectrum or beam width. There are so many devices, we cannot give you a simple answer. I did a search for both blacklight bulbs and UV LEDs including flashlights. There were no associated warning labels on the blacklight bulbs. The flashlights carried a warning to use special glasses and to never point the light into someone's eyes. That should be sufficient to question their use on a robot in close proximity to people.

[548swimmer]

I've had good luck getting UV reaction out of 470nm blue LED's. I installed them for my friends climbing wall in his garage, and all of the fluorescent holds glow as if they were under a black light. The neat thing about these LED's is that they are still solidly in the visible spectrum, so the blink reflex occurs. This wont be as significant as UV LED's, but should help.