Re: OPA695 current feedback amplifier

From: Rene Tschaggelar (none_at_none.net)
Date: 09/27/04 

Date: Mon, 27 Sep 2004 11:44:29 +0200

Yannick wrote:

>>yes i agree, sory i misunderstood slightly, the resistor inevitably adds
>>noise so leaving it out means you have less noise,
>>wich is what i think i said as well anyway, but i thought you were still
>>meaning the higher frequency wich you mentioned in the previous paragraph. i
>>wasnt fully awake when i read it lol.
>>
>
>
> hehe no problem
>
>
>>If i were you i would measure what signal you get when u reflect it off a
>>target, my estimate of 10% reflected back towards the lense was pure
>>gueswork. the real chalenge comes when u have a smooth dark surface that is
>>angled away from the detector.
>>
>
>
> indeed , the good news is that my phase meausurement works, i now can
> do distance measurement with direct light path on the photodiode. I am
> now gonne make a microcontroller interface wich does the ADC,
> calculations(phase-distance algorithm) and drives a DDS frequency
> synthesiser. After this i am going to replace my PIN photodiode with
> an avalanche one and the difficult part will began : measuring the
> reflection on a diffuse surface... i almost cant wait:)
>

Better don't wait at all.
I tried this almost 10 years ago and failed due to the little light
coming back. It was rather frustrating to see how little came back
from a white paper in 20cm distance. The ultimate surface was not
meant to be white and perhaps a bit farther away than 20cm.

Rene 

-- 
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

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