AnsweredAssumed Answered

vrf Photo Flash Intensity

Question asked by charles.stewart on May 22, 2008
Id like to thank everybody for there responses on this topic yesterday.
It has given me direction and a lot of cool things to think about. (I had a feeling flash meters weren't straight forward). Also pointed me in the direction of some new and totally cool equipment.

Thanks once again to all



>-----Original Message-----
>From: ext Ron.Simonson []
>Sent: 21 May 2008 19:31
>To: Stewart Charles (Vertu/ChurchCrookham)
>Subject: Re: [vrf] Photo Flash Intensity
>Good morning Charles,  I do not fully understand the task that you are
>trying to solve.  Will the flash tube be placed in an integrating
>sphere or other such contrivance to capture all the emitted light?  Or
>are you trying to capture the photons from a more focused, defined
>region?  I have not kept up with optics for some time now but I suspect
>that even though many flash lamps are pretty long duration emitters, a
>photo-cell may be a bit on the slow side.
>for photo-diodes is pretty straight forward in zero or reverse bias so
>I tend to use them this way for optical measurements.
>I think I would just use a photo-diode, a good fast trans-impedance
>amplifier, and a fast digitizing scope.  You can calculate area under
>the curve, peak amplitude, and the various timing bits as needed. 
>Maybe a good application of the Matlab code in VEE.  I tend to save the
>data on a computer and then use octave to do the analysis.
>Of course I do not know the end result that you are after so the above
>may or may not be relevant.  Do you need to be concerned with spectral
>response issues?
>What are the accuracy requirements on the measurements in time and
>Talk to you later.  Ron.

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