[Laser] OPT-101 vs PIN diode

[Art]

Hi Peter,

I also wonder if Gordon compensated for the difference in active area 
between the 2 different devices? Putting the 2 receivers under the 
same light source isn't a fair test due to the difference in active area.

Be careful using the OPT-101, if you have a signal that requires 3 
Khz of bandwidth and you set the OPT-101 up to receive 10 or 12 Khz 
wide, there will be a very substantial loss in NEP.

I wonder if you Gordon monitors the mailing list?

I'd be very interested to see a spectrograph of the noise vs 
frequency for both receivers in total darkness...as the relative 
noise output vs frequency basically defines the bandwidth of the 2 
systems. It's only a fair evaluation IF both systems show the same 
approximate noise output vs frequency.

I should also say that John tested an early OPA111 op amp with a 
Hamamatsu photodiode up against his preamp. He believed the PGP 
preamp had better performance, but I do not know if he corrected the 
results to reflect the much larger active area of his photodiode or not.

Anybody heard from John recently?

Art
.



At 03:47 PM 12/13/2006, you wrote:
>steve kavanagh wrote:
>>Art et al:
>>In my experience high impedance photodiode receiver
>>needs good shielding too.
>>There is very little technical info in the
>>Scatterpoint article so I don't really know the
>>answers to your questions with regard to that specific
>>design.  But if you are interested you can find the
>>2005 issues of Scatterpoint at
>>http://www.g0czd.clara.net/ukug/SP_2005/
>
>
>You can contact G0EWN (Gordon) at: g0ewn191 at yahoo.com
>
>He and I are good friends(he lives  5 miles north of me) and we do 
>lightwaves together. However I haven't used the pin diode RX like he 
>has. It does sound more sensitive than my OPT101 type though :-)
>
>Peter, G3PHO