[sudo-discuss] Spectral Response Curves

[Patrik D'haeseleer]

The figure <http://www.jneurosci.org/content/21/16/6405/F5.expansion.html>I
linked to earlier suggests the 50% drop-off should be around 420-520nm,
which covers pretty much all of the blue range of the spectrum.

The photodiode you listed seems pretty much a perfect match. No need to
muck around with narrow band-pass filters.

Patrik


On Tue, Nov 12, 2013 at 12:26 PM, Hol Gaskill <hol at gaskill.com> wrote:

> i was asking about bandwidth, not center frequency.
>
> good luck on your app, kenneth.
>
>
> Nov 12, 2013 11:50:29 AM, stcredzero at gmail.com wrote:
>
> >On Tue, Nov 12, 2013 at 11:06 AM, Hol Gaskill hol at gaskill.com> wrote:
> >
>
> >What's the badwidth you're interested in?
>
> >Call me Kenneth, then ask me the frequency. A band around 470nm is what
> we need to detect.
> >
>  Shooting from the hip, I'd recommend a photodiode
> http://media.digikey.com/pdf/Data%20Sheets/Opto%20Diode/ODD-470W.pdf if
> you just need a coarse signal that detects the band centered on 470nm.
>  Also, you could use an analog to digital converter or even just a properly
> dialed-in comparator to cut out the heads and tails of the spectrum.
> >
>
> >Not bad for a shot from the hip, but if you read the background, you
> might find it doesn't quite fit the distribution model. Making this out of
> a photodiode and other hardware will make this far less accessible and
> convenient than a smartphone app. The more accessible and convenient such
> measurement is, the more such data will be mentioned in reviews. The more
> such data is mentioned in reviews, the more careful marketers and
> manufacturers will be with measuring their products. (Also, non-maker
> insomniacs deserve good sleep too.)
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