# Laser diodes and LEDs **URL:** \ **Category:** Factual Questions\ **Created:** [October 24, 2002, 10:12am UTC](https://boards.straightdope.com/t/laser-diodes-and-leds/133656 "2002-10-24T10:12:46Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [October 24, 2002, 10:12am UTC](https://boards.straightdope.com/t/laser-diodes-and-leds/133656/1 "2002-10-24T10:12:46Z")
Is the technology employed in laser diodes very different to that in ordinary LEDs? With the advent of blue LEDs, will we soon have blue laser diodes? (or do we already?) ---
**Author:** ![Mr\_Creosote](https://avatars.discourse-cdn.com/v4/letter/m/74df32/32.png) [@Mr\_Creosote](https://boards.straightdope.com/u/Mr_Creosote)\ **Post date:** [October 24, 2002, 11:36am UTC](https://boards.straightdope.com/t/laser-diodes-and-leds/133656/2 "2002-10-24T11:36:11Z")
We certainly do have blue laser diodes. Nichia has been making diodes at around 400nm for a few years now. I believe there are plans afoot to introuce these lasers to DVD players in the future. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [October 24, 2002, 12:26pm UTC](https://boards.straightdope.com/t/laser-diodes-and-leds/133656/3 "2002-10-24T12:26:51Z")
The technology for the light-emitting part is the same, but a laser diode also has to have a resonator cavity, which an LED lacks. The traditional way of building a diode laser is simply to cleave the ends flat and rely on fresnel reflection at the semiconductor-air interface to act as your mirror. I know that more elaborate and careful diode laser cavities have been built, but they’re a helluva lot more expensive to construct, and I’ll bet that most laser diodes are still made the old-fashioned way. ---
**Author:** ![Urban\_Ranger](https://avatars.discourse-cdn.com/v4/letter/u/e9c0ed/32.png) [@Urban\_Ranger](https://boards.straightdope.com/u/Urban_Ranger)\ **Post date:** [October 24, 2002, 3:06pm UTC](https://boards.straightdope.com/t/laser-diodes-and-leds/133656/4 "2002-10-24T15:06:15Z")
We have LEDs and laser diodes covering most of the visible spectrum now. ---
**Author:** ![Mac\_Guffin](https://avatars.discourse-cdn.com/v4/letter/m/2bfe46/32.png) [@Mac\_Guffin](https://boards.straightdope.com/u/Mac_Guffin)\ **Post date:** [October 24, 2002, 3:39pm UTC](https://boards.straightdope.com/t/laser-diodes-and-leds/133656/5 "2002-10-24T15:39:01Z")
I want a blue laser pointer NOW damn it! But a green one would be nice. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [October 24, 2002, 3:43pm UTC](https://boards.straightdope.com/t/laser-diodes-and-leds/133656/6 "2002-10-24T15:43:21Z")
**particlewill** has seen through my question; all is laid bare. I want a blue laser pointer. ---
**Author:** ![micco](https://avatars.discourse-cdn.com/v4/letter/m/5f8ce5/32.png) [@micco](https://boards.straightdope.com/u/micco)\ **Post date:** [October 24, 2002, 4:57pm UTC](https://boards.straightdope.com/t/laser-diodes-and-leds/133656/7 "2002-10-24T16:57:57Z")
> [@](#): > > \*Originally posted by particlewill \* > \*\*But a green one would be nice. \*\* Spendy, but green… > **[ThinkGeek - Shirts, Toys, Collectibles & More | GameStop](https://www.gamestop.com/toys-games/thinkgeek)** > > View all results for thinkgeek. Search our huge selection of new and used video games at fantastic prices at GameStop. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [October 24, 2002, 5:01pm UTC](https://boards.straightdope.com/t/laser-diodes-and-leds/133656/8 "2002-10-24T17:01:53Z")
> [@](#): > > I want a blue laser pointer NOW damn it! > > But a green one would be nice. Green laser diode pointers have been available for some time now See the Edmund Scientific catalog, item **3122900** : [http://www.scientificsonline.com//ec/search/products.cfm](http://www.scientificsonline.com//ec/search/products.cfm) The green laser diode pointer isn’t a green laser diode, though. It’s actually a diode-pumped Nd:YAG laser that’s then frequency doubled to produce 532 nm light. (In other words, diodes produce infrared light that then drives an infrared laser even further in the IR, the light from which gets converted to light at half the wavelength by a frequency-doubling crystal. Got that?) A friend of mine bought one and disassembled one. About 90% of the interior volume is just the battery. The pump diodes, laser, and frequency doubler take up an incredibly compact space. At $325 a pop. though, it’s not something you do lightly. These put out about as mucxh as the red laser pointers, but because the eye is more sensitive in the green, it looks a _lot_ brighter.