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LED optics

Discussion in 'General Electronics' started by Quack, Jan 21, 2004.

  1. Quack

    Quack Guest

    Hi,

    I have seen some LED driven devices project a little rectangle
    (unfilled) at a distance of upto 10cm or so - i am wondering how this
    is done.
    Is it just a matter of a special lense infront of uBright LED's ?
    If so, where can i get these lenses, and what are they called.

    I cant seem to find anything through my google searches.

    (i can not take apart the above mentioned device to have a closer
    look, but it is definantly LED's).

    Alex.
     
  2. Jerry G.

    Jerry G. Guest

    It may have been an LED laser, something like a laser pointer. It would
    then have the proper defuser in front of the beam output at the level of
    where it has to be collimated.

    --

    Greetings,

    Jerry Greenberg GLG Technologies GLG
    =========================================
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    Hi,

    I have seen some LED driven devices project a little rectangle
    (unfilled) at a distance of upto 10cm or so - i am wondering how this
    is done.
    Is it just a matter of a special lense infront of uBright LED's ?
    If so, where can i get these lenses, and what are they called.

    I cant seem to find anything through my google searches.

    (i can not take apart the above mentioned device to have a closer
    look, but it is definantly LED's).

    Alex.
     
  3. Quack

    Quack Guest

    It may have been an LED laser, something like a laser pointer.

    Im 99% sure its just a normal LED.

    For example, search for some 'IR proximity sensors' on
    www.farnell.co.uk, rswww.com or digikey - read the PDF's and they
    specifically say "Laser" or "LED" depending - and they mostly have
    some kind of aiming spot too.
    How are those done ?

    Most of those are round dots, about 5mm dia. at 10cm - but i have seen
    other shapes - and the PDF's would have to say "laser" if it contained
    one.

    These devices cant be opened without being completely ruined, and they
    get very expensive :(.

    Alex.
     
  4. Martin Brown

    Martin Brown Guest

    Almost certainly it is a combination of a mask illuminated by an LED and
    projected by a crude convex lens. Like a slide projector only smaller.

    Regards,
     
  5. I have a cheap laser pointer that came with a set of graphics 'masks'.
    These appear to be some sort of holograms that just snap over the end of
    an otherwise standard, inexpensive laser pointer. There are no optics
    invoved (other than those in the pointer) and the masks look like clear
    flat plastic under ambient light.
     
  6. Quack

    Quack Guest

    Almost certainly it is a combination of a mask illuminated by an LED and
    Yes, it must be - thats what i think.

    (as for the laser comments, its really not bright/high contrast enough
    to be a laser, i know the laser graphic thingies mentioned above, and
    its nothing like that - at over 10cm it would be barely visible in
    this case)

    So, assuming its just some mask/lense arrangement, does anyone know of
    anywhere these can be purchased, if they are a standard thing ?
    Perhaps there are LED's available with this kind of lense 'built in',
    and can be used normally without having to make anything special.

    Alex.
     
  7. Smiley

    Smiley Guest

    I strongly suspect that this is a diode laser pointer that has a
    hologram at the output. You can buy them pretty cheaply with as many
    as 40 different images you can change out.

    Joe
     
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