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Discussion and Support for the OptiTrack, SmartNav and TrackIR brands by NaturalPoint

Safe for your eyes?

by michael112 » Tue Dec 05, 2006 2:03 am

Is it tested what long time trackir4 causes to eyes?

Can it be used so that the device is set to place eyes dont get the "waves" from it. For example slightly above monitor so you wont see it under the cap. Will it work normally if its littler upper than headlevel? Does these waves from the device go through a cap?
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by Schnurx » Tue Dec 05, 2006 4:37 am

Doh.... what "waves" are you speaking off? Is this a joke or will this detoriate to some bit of esoteric "quantum" mumble?

It's simply some red LEDs and a camera. LEDs have very low Energy output and no harmful "rays" at all. Well, except if they would use Laser Diodes.
Which they don't for obvious reasons.
If you're still scared, you can place the device behind your head, adjust the software accordingly (in settings) and voila. Except of course, if you have a third eye in the back of your head.
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by michael112 » Tue Dec 05, 2006 6:18 am

I was speaking electromagnetical rays which can be harmul in long run if its specific kind..

So there isnt infrared waves coming from the device? or what? If I set it behind me can I invert the way it register head moves?
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by Schnurx » Tue Dec 05, 2006 7:40 am

Yep, I believe it emits infrared. Like every television remote control does. AFAIK there are no health detrimental effects at all from infrared radiation.
Well... at least not if you don't fry someone with say 10 kilowatts or so of power.
TIR probably uses even less power than a tv remote, after all it is powered from the USB-Bus.Which really isn't designed to deliver much power.

And yes, you can invert it.
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by michael112 » Tue Dec 05, 2006 8:39 am

You dont need to fry your eyes to ruin them. Im intrested in long time effects of trackIR rays to the non-renewable cells in one's eyes. These cells are very sensitive!!!
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by VincentG » Tue Dec 05, 2006 10:17 am

The TrackIR operates by tracking reflected or emitted IR light that is imaged by a CMOS sensor. The sensor and emitters are tuned to 880nm, slightly above the visible spectrum, you can see them emit a slight glow when the room lights are off, this is the very upper end of the red spectrum. The sensor and IR LEDs are covered by a very special plastic that we custom designed with Bayer to block all light below 820nm, it passes all light above this point, it is called a band pass filter.



The LEDs emit at 880nm and are standard off the shelf IR LEDs, we run them all the time when the unit is turned on. There are 4 of them and they each have a total radiant output of about 23mw/sr, which is 23miliwats per ster radian. Total output power is NOT 4 X 23 mw/sr as the LEDS do not overlap exactly; they create a coverage pattern with slight overlap at the edges. Also, the LEDs to not emit a uniform brightness, they have an angle to half intensity, so the center of the overlapping LEDs is the SAME brightness as the center of each LEDs output, hope that makes sense.



Your eyes ARE sensitive to IR light, you can�t see it, but your eyes will register the �power� of the light, your pupils will shrink down as if you were looking at light in the visible spectrum. Remember, we are just slightly above red in the visible spectrum. You won�t feel your pupils getting smaller when our device turns on because we are a relatively low level of light for an average room condition. If you turn out all the lights in the room, put the unit about 1 foot away from your face and watch your eyes in a mirror, you will see your pupils contract, they are �seeing� the IR light.



As for the amount of power the LEDs output, it is many of times lower than simply going outside, not to mention on a bright sunny day. As I had seen posted before, we are a small fraction of the IR output from a normal incandescent light bulb. ANSI references spec ANSI Z 136.1 � 2000 for laser power emission, but we are not a laser, so in the back of the spec they reference ANSI/IESNA RP-27.1-96, which is the spec for lamp output, basically what we are and what ANSI says to use. Maximum exposure for our wavelength range, which is from 700nm to 1100nm is 10mw/cm2. To convert our power output, which is about 30mw/sr, we apply sr x 1cm2/distance2. Typical user distance is 18� or about 45cm (on the conservative side, most users are further away), so 30mw/2025 = .015mw/cm2. Needless to say, we are on the safe side!



If you have any further questions or concerns please let us know.
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by Schnurx » Tue Dec 05, 2006 11:54 am

If they were anywhere that close to sensitive as you imagine, you would be blind for a long time now.
Every light bulb, ever fire, everything that generates heat at all also generates infrared rays. And often with much more energy than the few milliwatt of the IR-Leds.
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by michael112 » Thu Dec 07, 2006 2:49 pm

So is trackIR 4 tested by some government-product-safety-bureau or whatever they are called?

I'm sorry for these questions Im not trying to be an idiot ,just being overcautioned.
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by VincentG » Thu Dec 07, 2006 3:02 pm

Actually, it hasn't been tested by the http://www.ansi.org/, but we are using the government standard for the type of device that we are; Which states that the IR must be below this level to be considered safe (10mw/cm2). Our product is about 1/500th of that standard (.015mw/cm2).
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