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Why do most optical mice use red LEDs?

  • Is it necessary that a mouse's LED is red?
  • What other colors can/can't be used?
  • Does using another color changes the main design of the mouse?
  • Does it makes manufacturing mouses harder or more expensive?
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    en.wikipedia.org/wiki/Optical_mouse#LED_mice: "The color of the optical mouse's light-emitting diodes can vary, but red is most common, as red diodes are inexpensive and silicon photodetectors are very sensitive to red light." Jun 3, 2013 at 3:57
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    I'm not sure why this is getting downvoted... it's actually a pretty interesting question. The question could use a little editing, but there's nothing fundamentally wrong with it. I'd be interested in seeing an answer that actually explains how an optical mouse works and why red might be preferable.
    – nhinkle
    Jun 3, 2013 at 4:21
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    There's a lot of blue (like bluetrack mice) and IR led mice too. Red LEDs are cheap tho, and have been around the longest
    – Journeyman Geek
    Jun 3, 2013 at 4:24
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    @nhinkle Maybe because "this question does not show any research effort"? People are linking to Wikipedia articles…
    – Daniel Beck
    Jun 3, 2013 at 7:09
  • @techie007 I saw the Wikipedia article, but those 2 lines didn't satisfied my knowledge hunger. I tried to search for it, but I didn't find a good detailed explanation. Also never asked in any SE sites, so this could be a potential Google search landing page. I also agree with nhinkle.
    – totymedli
    Jun 3, 2013 at 11:39

3 Answers 3

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It is not necessary that it be red. Any color can be used, even invisible (infared). The aesthetic design usually does not have to change, but internally it may due to the different type of laser diode. Red lasers are cheaper and readily available. Other colors do exist in consumer products currently, the most popular alternative is green.

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Is it necessary that a mouse's LED is red?

No.

What other colors can/can't be used?

Any colour can be used.

Does using another color changes the main design of the mouse?

No.

Does it makes manufacturing mouses harder or more expensive?

Both.

For more information, see this Wikipedia article.

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    It'd be nice if you could expand your answer to more than just a few words, but add a little context and explanation.
    – slhck
    Jun 3, 2013 at 5:58
  • @slhck: Fixed in an edit.
    – bwDraco
    Jul 7, 2016 at 0:51
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Red colour has the most dispersion compared to other colours in the visible spectrum, violet having the lowest.

Dispersion means how much light can 'spread', 'disperse', 'scatter', etc. It is the same reason that traffic lights for stop are red. This is so that the sign is visible even from long distance & with different viewing angles.

For similar reasons the mouse may be using the red colour. Not everybody uses the mouse on perfectly flat surfaces!

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