[sudo-discuss] Spectral Response Curves

[Steve Berl]

I will check with folks at the East Bay Astronomical Society up at Chabot
Space & Science Center. There is some amount of spectroscopy equipment
around up there. Though much of it is very old, and intended for
astronomical observations (attached to a telescope), something might be
useful, and there might be someone who is interested in helping out.

-steve


On Tue, Nov 12, 2013 at 12:42 AM, Marc Juul <juul at labitat.dk> wrote:

> You might want to repeat the question on the Counter Culture Labs mailing
> list:
>
>   https://counterculturelabs.org/
>
>
> On Mon, Nov 11, 2013 at 2:47 PM, Peter Kwangjun Suk <
> peter.kwangjun.suk at gmail.com> wrote:
>
>> (Also posted to Noisebridge. Skip if you are experiencing deja-vu.)
>>
>> Hello,
>>
>> Right now, I'm doing research for a specialized app to let consumers
>> validate products that can be used to treat insomnia. Specifically, I'm
>> working on a smartphone app that can act like a light detector for light in
>> a narrow band around 470 nanometers. This is the frequency that has been
>> shown to suppress melatonin secretion by the pineal gland.
>>
>> There are specialty products for avoiding late night 470 nanometer light
>> exposure (light bulbs, screen overlays, glasses) but these are often very
>> overpriced, and there is no convenient way to validate them. There are also
>> "ordinary" products that serve the same purpose, but there is no good way
>> for people to accurately test them. Currently, people can use a CD or DVD
>> as an ad-hoc diffraction grating and look at the resulting spectrum, but
>> even this isn't quite good enough. I've bought a narrow bandpass filter for
>> 470nm light, and even products that have a spectrum that "looks good" (very
>> little blue) can have hot-spots that leak large amounts of 470nm light, and
>> it doesn't take much to suppress melatonin. (As low as 0.5 lux for
>> prolonged exposures.)
>>
>> Looking generally at spectral response curves for digital cameras, it
>> should be possible to "synthesize" a narrow band detector by taking the
>> blue channel response and subtracting the red channel value.
>>
>>
>> http://www.maxmax.com/images/Cameras/Technical/NikonD200_SpectralResponse.jpg
>>
>> This should effectively produce a "synthetic" instrument that has a
>> spectral response curve that would be the camera's blue response, minus its
>> red response. Even more helpful, the user should be able to view a
>> synthesized narrowband image of the product, to be able to spot leaks and
>> hot spots.
>>
>> What I need: I would like help in scientifically measuring the spectral
>> response curve of the "synthetic instrument." I already have a (tiny) 470nm
>> filter from Thorlabs, and I'm already aware of Public Lab's DIY
>> spectroscope. I would like to use more accurate equipment, however. It is
>> important that I can provide accurate information about the performance of
>> the app and use rigorous procedures for measurement so that users know they
>> can rely on the instrument.
>>
>> Does anyone have the expertise and access to equipment to help me out?
>>
>> --SCZ
>>
>>
>>
>> --
>> There's neither heaven nor hell,
>> save what we grant ourselves.
>> There's neither fairness nor justice,
>> save what we grant each other.
>>
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>>
>
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-- 
-steve
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