A Conversation for Lasers
Earthman Started conversation Sep 19, 2001
The comment on gas lasers being the only stable ones operating in the blue/ultraviolet range isn't quite true any more. There are now blue laser diodes, based on InGaN. The technology is rather new (the first one was made in the 1990's), and still has room for significant improvement, so it hasn't been widely commercialised yet. However, in the (near?) future, these blue laser diodes would be expected to provide a dramatic increase in data storage capability in compact disk and CD-ROM devices, and such rewritable technologies as HDTV-capable DVD and the emerging DVR formats, as the amount of data that you can store in this way is related to the wavelength of the laser used.
Earthman Posted Sep 19, 2001
Ahem. Sorry, should have said - InGaN is Indium Gallium Nitride.
Dr Hell Posted Sep 19, 2001
They key word was stable.
Those blue diodes are expensive and have a life of 'only' 1000 hours. (which is very good for a start)
More disadvantages: Lo power, expensive.
Okay, so they do exist - of course, and they are cool I never denied that... But for real heavy duty applications they are not quite ready yet.
Glad you read.
Dr Hell Posted Sep 19, 2001
Maybe the paragraph should go like this:
[Gas lasers are] *currently* the only stable...
No doubt someone's gonna find a good blue diode laser someday. And a green one too.
Bye - Thanks again for reading and commenting,
Earthman Posted Sep 20, 2001
Depends on your definition of 'stable' I suppose. Sony seem to think it's stable enough (or will be pretty soon) - they demonstrated a DVD RW Dual Compatible Recorder using a blue-violet laser diode earlier this year at the Consumer Electronics show in Las Vegas. But I don't think you can't buy it yet.
Dr Hell Posted Sep 20, 2001
Yeah... Blue diodes are comming, sure, but they are not quite there yet. They are still too expensive for commercial uses (2000 bucks for a weak diode) And their life is of about 1000 hours (that's 41,6 days). Alternatively you could use it 2 hours/day for almost 2 years. And what then? Spend another $2000? That is what I meant by unstable.
As for the other applications: Cutting, drilling, microchip fabrication, advanced science... Their performance is too low.
The laser light is not high quality (as for most diode lasers) it's not high-power...
Anyways... Sure, they're comming. But my guess is that we'll wait some 5 years until they are used in CD-Players and the like - remember, that's just one tiny application for laseres and they don't have to be really good. Until then the most stable heavy duty state of the art blue/UV laser generators will continue to be gas-lasers. For precision applications I see no near future for the diodes.
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