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Science Technology

LEDs for the Blind 30

Posted by michael from the better-than-a-marble dept.
boowax writes "Tired of being blinded by those annoying laser pointers that have found their way into all sorts of places for the convenience of corporate presenters? Looked too closely at the underside of your optical mouse? Are you just dumb enough to look directly into a laser? Well, fret no more, for here is a new technique for stimulating and healing those damaged retinal cells using LEDs. Its also being tested for use in treating similar problems caused by mucositis (a side effect of chemotherapy) and other eye related maladies."
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LEDs for the Blind More

LEDs for the Blind

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  • I always thought it was just a regular LED. Do optical mice like my Cordless Mouseman have actual lasers? The light spreads so much it does not definitely look like a laser, but i know nothing about hardware, so could anyone enlighten me on this?
    • that bit about the mouse was a bit of a joke actually..i've had several people tell me that the box their optical mouse came in said it uses a laser. Yes, as far as I know, they're all LEDs, but that doesn't stop stupid people from seeing red and thinking its a laser.

    • Optical Mice use LEDs, *NOT* Lasers. (Score:4, Informative)

      by BigBlockMopar ( 191202 ) on Saturday July 13, 2002 @12:19AM (#3875424) Homepage

      I always thought it was just a regular LED. Do optical mice like my Cordless Mouseman have actual lasers? The light spreads so much it does not definitely look like a laser, but i know nothing about hardware, so could anyone enlighten me on this?

      Well, like the filament of the rectifier tube in my 1939 Stewart-Warner radio, it hurts my eyes to stare into it, and it's red, but it's definitely not a laser.

      Lasers come in wavelengths (colors) ranging from invisible to invisible, and everything in between. For a variety of reasons, almost all the lasers you're likely to encounter will be red or IR (invisible).

      You can tell a laser from any other source of light very easily:

      • Is the light coherent? As in, if you shine the light at the house across the street, does the dot appear to be the same diameter as it was when you pointed it at your hand? Coherency is a basic feature of laser light; some spread is normal, but if it spreads like a flashlight, it's not coherent.

      • Speckle. Laser light almost always appears speckled. Regular light consists of an infinite number of wavelengths of light mixed to make white. Ranges can be filtered out with sheets of glass, plastic, etc - think of sunlight in a stained glass window, there may be 300 different wavelengths that we would describe as red light. But laser light is at a peak wavelength, with some slight impurities. But it's very precise. If all your light is at one wavelength, when it hits an imperfect (ie. any) surface, some light will reflect back 180 degrees out of phase and cancel itself out (like adding -1 and +1, they cancel to zero). This accentuates imperfections on the reflecting surface in the form of speckle.

      I don't see either one of these behaviors with the light from my own Mouseman. So, all I can assume is that it's merely a bright LED.

      LEDs are certainly bright enough: many cars use LED third brake lights, some new Cadillacs and Mercedes are using them as the main taillights, and I've seen traffic lights in Toronto (Eglinton East at Sloan) and Ottawa (Gladstone at some intersection between Preston and Bronson), so LEDs are certainly up to the task of lighting an image of my mousepad.

  • how many ./'ers are going to need to this IR LED treatment after checking their optical mouse to see whether it is in fact a laser. |-)
  • I am glad to see things advancing to this. For too long we have been dependant solely on drugs, and even though they have done good, it has come with consequence. But I think as experience meets science in the world of treatments other than just mainstream drugs, things in the medical field will begin to advance substantially. We have such amazing resources at our disposal, but in medicine, one of the most amazing tools is our own bodies. Our healing mechanisms and our immune systems are not to reckon with. Once we learn how to stimulate and properly understand our own medical mechanism, we will have definitely come a long way.

  • Optical mice don't use lasers (Score:3, Informative)

    by Spunkee ( 183938 ) on Thursday July 11, 2002 @12:57AM (#3862677)

    All the optical mice I've seen don't use lasers. If they did, they'd be required by law to have the standard laser warning sticker [nmsu.edu] in plain view on them. I have yet to see a mouse with such a sticker.

    They just use very bright LEDs. If you think about it, that's all that's really necessary. It just needs to illuminate the surface under the mouse with a color that the sensor is sensitive to.

  • The light from a regular LED looks nothing like that from a Laser Diode. Even the cheapest laser pointer has wonderful "scintillation", where the lighted area appears to sparkle.

    This is caused by head and eye motion changing the light pathlength and interference patterns. It gives laser light a unique sparkle and shimmer that ordinary LEDs can only aspire to.

    So the LED on the optical mouse is clearly not a laser, just ordinary light for lighting up the mousepad. And the cheapest $2.99 laser pointer really is a laser.
  • I wonder if this means I can now stare directly at an eclipse?

    I've always imagined that the experience would be the equivalent of 'staring into the face of god' or 'eating the apple in the garden of Eden'.

    If we can cure the eye damage, maybe I can start a cult and live happily ever after. :-)
    • You can stare directly at an eclipse, like I did when I was 5. Just make absolutely sure it is during totality, ie not a penumbral or annular eclipse.
  • Some people are always going to try the "don't try this at home" tricks.

    I remember having a physics lession; something about sound. Anyway, we had a couple of tuning forks.
    The teacher said: "Oh, by the way, don't put it to your teeth! That would make your enamel shatter".
    You can guess the rest.

    I, for one, don't want to give anyone any bad ideas. So forget you ever read this!
    • This was offtopic, so I'll go even farther off... I'm a violinist, and use a tuning fork to tune my instrument. The best way I've found, is to hold the fork between your teeth and let the sound resonate through your head. This way, you can hear it even with 50 other people tuning at the same time. It doesn't do anything to you teeth. Maybe other frequencies do, but 440Hz doesn't.
    • Tuning forks are a handy way to test for broken bones. Start the fork humming, then hold the handle against the bone where it is closest to the surface of the skin. If it's broken, the area of the break will hurt-- a lot.

      Or so I was told in EMT class. AlthoughI have seen this done by professionals; I don't know if it really works.

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