Le 01/08/2012 14:26, Invisible a écrit :
> suggests that there's no such thing. Now I wonder... Are there any
> devices which actually use LEDs for display? Or are all the devices
> which I thought were LEDs actually VFDs?

A Led is a small spot, with a small emitting cone, about 15° to 25°.
If the form was bigger that a point, it was not a Led.


> 
> Also, I somehow ended up reading about lasers. I still have no idea how
> to make one, but I did come across several /ridiculously/ cool images:
> 
> http://tinyurl.com/mxe5tn
> http://upload.wikimedia.org/wikipedia/commons/4/4b/Laser_DSC09088.JPG
> 
> Quite why you'd be wearing combat uniform while working in a lab, I'm
> not sure. Also why you'd be wearing shades in a dark room. (Although
> perhaps a room with lasers in it makes this a reasonable safety
> precaution.)

You missed the main point on the guy: the goggle are not sun glasses,
they are teinted glass to protect against the laser specific color.

About wearing shade/combat... well, uniform is mandatory inside the
facility. This is a summer-uniform.


> 
> Hmm, I wonder if I could somehow make a laser using normal air as the
> optical medium?

normal air... depend if you can breath in neon, then neon would be your
normal air.
Laser need an atom or molecule getting excited and returning to lower
energy with always the same emission of light (frequency)(and a few
noise around).
You push in white light (full of noise) and get back a lot of one
lambda, dismissing the noise within the resonant cavity (the two
mirrors, one of them being less than perfect).
normal air is 20% O2, 79% N2, ... and when you are around, a bit of CO2.
Stressing O2 or N2 with energy would make them group as O3, N3, NO2...
probably not a good ground to have a laser.

It is possible to have laser-led: it works differently (no mirrors),
it's a single lambda, but the parallelism is not the one of laser until
you post process it with a lens. The power is also far smaller.

-- 
Software is like dirt - it costs time and money to change it and move it
around.

Just because you can't see it, it doesn't weigh anything,
and you can't drill a hole in it and stick a rivet into it doesn't mean
it's free.

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