100W Laser LED Why Not?

[kandrey89]

I'm new to lasers, but I was wondering, why couldn't the power of a 100W LED Diode be harnessed and made into a laser through the use of options and what not?

Is the scattering too much, it's not a single crystal that's giving off light, the area of output is too big to be coalesced into any meaningful burning laser, an other reasons? or am I wrong somewhere, please explain!

 

[hydrogenman15]

An led emits incoherent light (aka there waves don't move in line with each other).
You can't focus it like a lasers light.

--hydro15

 

[diachi]

You can't focus incoherent light to a small point. Also 100W isn't the light output , it's how much power the LED uses.

 

[Benm]

An led emits incoherent light (aka there waves don't move in line with each other).
You can't focus it like a lasers light.

--hydro15

The main problem is the size of the light emitting area - in a diode laser its in the order of the wavelength, in that LED is absolutely huge. Those little dark areas actually look like individual LED dice.

Also 100W isn't the light output , it's how much power the LED uses.

True, but if its a bit efficient, it would be capable of 10W or so optical output power. Still massive, and if all you want to do is burn something, its likely to work given correct optics.

 

[Cyparagon]

Yeah, it looks like 10x10 1-watt emitters.

LED != laser although you may be able to pump a few lasers with LEDs.

 

[Laser_Ben]

Benm is the only one even close here! :'( :'( :'(

You could make that beam collimated. The problem is when you change the divergence, the diameter gets larger. We have done this with Luxeon Die at work for illumination products where the beam can be made to 10's of miliradians. While this is nice, the beam on the 1mm x 1mm die comes out to be about 3x3 cm. It would be much larger if used on the giant die here.

The only reason that the coherence maters is in the actual lens used. Typical lenses will have different focal points based on the wavelength. To correct this, you have to use a achromatic lens. This is a pair or triplet of lenses that are glued together. It prevents the typical effect of different focal points.

Granted it wouldn't be a laser...

 

[nikokapo]

I was gonna give you a complete and extensive answer, but you pretty much got it in the first posts.

The thing is that, as the members said, LEDs produce incoherent light, which means that it's photons are not in phase with each other.

( What is 'phase'?: http://en.wikipedia.org/wiki/Phase_(waves) )
(More info about this: http://en.wikipedia.org/wiki/Polarization).


This was explained in some threads in this section, repeated times. If you lurk thru the older threads you will find a better explanation