[Laser] LED vs Laser diode

[Bob Blick]

On Fri, 21 Mar 2008 12:27:27 +0100, "Alberto di Bene" <dibene at usa.net>
said:
> I know almost nothing about light communication, but this summer I will
> perform some experiments.
> I have just a question which will show how ignorant I am in this field.
> I bought at an ham fair a Luxeon 3W white LED. What I would like to know
> is how does it compare, in terms of quantity of 
> light received at distance, with a laser diode ? Suppose that both are
> reasonably focused with a lens.
> So, what is the mW equivalent from a laser diode of that 3W Luxeon LED ?

Hi Alberto,

The LED has a wider angle than the laser diode. If you use merely a lens
on the LED you won't get much benefit over a laser diode. But if you use
a parabolic reflector and a lens you can get more of the light, but
collimating that combination is very difficult.

LEDs are also slower. Here is a crude test I did a few years ago:

http://bobblick.com/led_speed_test/

Cheerful regards,

Bob

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