On 17 Sep 2005 at 15:48, Russell McMahon wrote:
> How about expanding the timescale and triggering on the falling edge.
> The attached diagram is the falling edge from your 45 mA LASER diode 
> plot.
> The small divisions on the axis represent 100 nanosecond.
> What it tells us is that your detector is surprisingly good despite 
> what people have suggested, that your signal generator is reasonably 
> fast, and that the detector comes close to being prescient :-). 
> Something like 50 ns/division or faster would be interesting.

Hi Russell,

I will do this round of tests again sometime, but with a better test jig. 
My signal generator is a good 100MHz unit, and the photodiode I 
chose is also fast enough, but I just did this all with clipleads. 
There's enough coupling to explain your "prescient" remark. I did 
this test mainly to see how slow white LEDs were, not how fast, and 
it did its job. If I sped up the sweep without improving the setup the 
details would not be real.

But we already know laser diodes are pretty fast(or at least I did), so 
I'm not sure how much more we'll learn.

Cheerful regards,

Bob

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