12 Nov
2013
12 Nov
'13
12:33 p.m.
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(a)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(a)gmail.com wrote:
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.
On Tue, Nov 12, 2013 at 11:06 AM, Hol Gaskill
hol(a)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.
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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