# Why are laser/red dot sights typically red? **URL:** \ **Category:** Factual Questions\ **Created:** [February 9, 2009, 6:59am UTC](https://boards.straightdope.com/t/why-are-laser-red-dot-sights-typically-red/485025 "2009-02-09T06:59:46Z")\ **Posts on this page:** 2\ **Page:** 2
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [February 9, 2009, 10:05pm UTC](https://boards.straightdope.com/t/why-are-laser-red-dot-sights-typically-red/485025/21 "2009-02-09T22:05:05Z")
> [@Q.E.D](#): > > I have to disagree with this to an extent. The ability to make a blue LED is absoultely a prerequisite to the ability to make a blue diode laser since the emitted wavelength is dependent upon the semiconductor chemistry. The light-emitting p-n junction is, for all practical purposes, identical in both devices; the main difference between an LED and an injection-type diode laser is the optical cavity–and that’s entirely mechanical. It took two years of work to go from blue LED to blue LASER, and commercial viable blue lasers took a decade more. So, I stand by my statement. [http://archive.sciencewatch.com/jan-feb2000/sw\_jan-feb2000\_page4.htm](http://archive.sciencewatch.com/jan-feb2000/sw_jan-feb2000_page4.htm) ---
**Author:** ![Bobotheoptimist](https://avatars.discourse-cdn.com/v4/letter/b/919ad9/32.png) [@Bobotheoptimist](https://boards.straightdope.com/u/Bobotheoptimist)\ **Post date:** [February 9, 2009, 11:16pm UTC](https://boards.straightdope.com/t/why-are-laser-red-dot-sights-typically-red/485025/22 "2009-02-09T23:16:27Z")
Green lasers are a whole lot easier to see, which is why I waited for a 25mW green for my AR. Price has come down so I suspect we’ll be seeing a lot more [Previous page](https://boards.straightdope.com/t/why-are-laser-red-dot-sights-typically-red/485025.md?page=1)