lasernvb said:
Now what are the main factors affecting a laser's burning capability and beam quality? Is it the diode, or crystal or the optics?
Yes. All those things affect it. Diodes give a fairly funky beam (read: not circular), so to get a good beam or the ability to burn things, you need some lens action. A fairly simple focus lens will do you good for burning, just focus it to a pinpoint, so the Aixiz and Meredith modules that DIYers use will be fine. If you want really high beam quality, you need some more lenses, but at least for me and many others, focusing the Aixiz/Meredith way out towards infinity does fine for my needs (my needs being "ooooo, pretty color" in the dark).
As far as manufacturers, well, who knows? The person selling it may know where it came from. A lot of companies make diodes, and the company who made the sled/player may not have made the diode. Sony, Sharp, Nichia, lots of big names make them, as well as a lot of little names. For a particular part you may be able to look up it's history, but people generally don't say "well Sony is great, but I've had some real dogs from Sharp". Quality control on these things is generally really high, so really the worst they'll ever be is good.
The best diodes? Well, depends what you want. Let's start with color: Ir (808nm is popular), 650nm red is very popular, you can get 635nm orange/red, and 405nm violet. All of these are pretty in expensive. If you really want to, you can get up to about 473nm blue diodes for DIY, but these will cost you (thousands of USD). Then, there's power. Do you want to burn? Do you want to see the beam? Do you jsut want a cooler color than all your friends for presentations? There's something out there for almost everybody in diodes. (Just no green laser diodes. Yet.)
And DPSS, which is moving away from DIY (although people still do this sometimes as DIY), opens up whole other worlds of possibility.
Laser diodes are like ice cream, what flavor do YOU like most?
