
New quantum-dot spectrometer is small enough to function within a smartphone - user_235711
http://newsoffice.mit.edu/2015/quantum-dot-spectrometer-smartphone-0701
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Animats
It's a way to build a multispectral imager out of a CCD imager, with lots of
different narrow-band filters over different pixels. Humans have 3 color
sensors; some birds have 22, which helps in recognizing specific plants. This
is more useful if it extends outside the human visual range, into IR and UV.

Applications are somewhat limited. It's useful for forensics [1], farming
(weed and sick plant identification)[2], and some kinds of industrial
inspection. For farmers, it's more useful on a drone than on a smartphone;
they can fly over the fields and look for trouble spots.

[1]
[http://www.beneaththewaves.net/Photography/Uses_of_Multispec...](http://www.beneaththewaves.net/Photography/Uses_of_Multispectral_Photography.html)
[2] [http://www.marcusuav.com/using-multispectral-cameras-with-
sm...](http://www.marcusuav.com/using-multispectral-cameras-with-small-uavs-
for-precision-agriculture/)

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bglazer
To those who are more familiar with spectrometers:

What's the most interesting "consumerish" application that you can think of
for a spectrometer? I imagine health related applications are an easy target
because spectrometers are already widely used in biology. Are there other,
more off the wall applications that don't make sense now, given the cost and
size of a spectrometer?

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Balgair
Depending on how good the specm is, just about as many uses as a camera.
What's this leaf? Whats this red stuff? What kinda soil and I standing on?
What is the air pollution like today? Is this bleach? Is that really gold?
What is this IC made of? What is my baby's heart rate, does she have the flu?
What grade of steel is this wrench? How old is this picture of gram? How new
is this gasket? Is this chicken what I have, or fish (from the lips of Mrs.
Lachey (nee Simpson) herself)?

It's mostly what questions as to materials, depending on how good the specm
is. Combine this with your phone's camera for other optical measurements (IR,
size, shape, position, etc), some gps data, maybe some tracking of your amazon
history, and you have a device that might be able to tell you what anything
ever seen is to reasonable certainty. There is without any doubt, a large
market for that.

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spudlyo
_Depending on how good the specm is..._

The article says that besides being small it's also high bandwidth and high
resolution. Not sure how many distinct things you can identify based on
spectral analysis alone, but I have high hopes for one day owning a Tricorder
like device. Being able to fingerprint and identify real world stuff we might
ingest seems huge, am I drinking Coke or Diet Coke? Vodka or Gin?

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dzhiurgis
> am I drinking Coke or Diet Coke? Vodka or Gin?

Society didn't take MyVessyl.com really well.

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spudlyo
Your friends might roll their eyes at you putting Soylent in your Vessyl and
monitoring your daily caloric intake on your Apple Watch either, but nerds
want what they want.

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CamperBob2
I'd like a better understanding of why this is better than an ordinary RGB
camera sensor by itself, at least as far as visible light is concerned. What
would be an example of a wavelength that couldn't be disambiguated from some
other wavelength by looking at its relative amplitude through R, G, and B
filters? What do the extra degrees of freedom afforded by the quantum dot
filters buy us? Could adding a fourth color filter to some of the elements in
a CCD sensor accomplish the same thing?

Is it just a matter of the line width of a typical color filter being too
broad?

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InclinedPlane
RGB camera sensors can't identify specific wavelengths, all they can tell you
is that a given wavelength is in some specific range. And when the light is
not monochromatic then it becomes impossible to determine the spectral
pattern.

~~~
Gibbon1
I think these sensors implement n color vision, working a lot like the ear
does. Instead of just detecting three colors you detect hundreds of colors.
With each dot tuned to a fairly narrow band of light you get good selectivity.

~~~
CamperBob2
Right, I'm just wondering how many discrete sensors you need before you can
say you have a "real" monochromator. This scheme appears to work a lot like an
RGB sensor, but with more than three filters.

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ngoldbaum
One step closer to a real life tricorder.

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hengheng
Here's the link[1]. We're actually looking for micro UAV compatible
hyperspectral cameras that have a significant number of pixels in any one
direction.

[1]
[http://www.nature.com/nature/journal/v523/n7558/full/nature1...](http://www.nature.com/nature/journal/v523/n7558/full/nature14576.html)

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mrfusion
I'd like to see these mounted under a car to warn you when you're hitting ice.

A lot of times you can't see it. the roads can be wet and then certain areas
start freezing. You slow way down once you start seeing ice patches.

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digikata
Does ice return a different spectrum than liquid water?

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moron4hire
No, but couple it with thermal imaging and "water, 0C" is ice and "water, >0C"
is rain.

