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All Over But the Funding: Open Hardware Spectrometer Kit

Posted by timothy on from the what-is-the-exact-color-of-your-van? dept.

New submitter mybluevan writes "The Public Laboratory for Open Technology and Science is putting together an open hardware spectrometer kit on Kickstarter. The kits are built using an HD webcam, discarded DVD, and a couple other odd bits. They've also put together a kit for your smart phone and open-source software for desktop, Android, and iOS. Need to analyze the contents of your coffee, the output of your new grow lights, or a distant star on a budget? Just build your own spectrometer, or pick up the limited edition steampunk version." Besides making cool hardware, they'd like to "build a Wikipedia-style library of open source spectra, and to refine and improve sample collection and analysis techniques. We imagine a kind of 'SHAZAM for materials' which can help to investigate chemical spills, diagnose crop diseases, identify contaminants in household products, and even analyze olive oil, coffee, and homebrew beer."

8 of 62 comments (clear)

  1. Finally! by ColdWetDog · · Score: 4, Funny

    A use for all those Windows ME disks!

    (You need a DVD as a diffraction grating.)

    --
    Faster! Faster! Faster would be better!
  2. Pretty cool ... by RockDoctor · · Score: 5, Interesting
    That's an interesting combination of technologies and materials. The basic idea should be workable, but how workable they'd be for material identification given the prevalences of IR filters on (consumer grade) CCD sensors and their relatively low sensitivity ....Identifying spectral lines on a 10-bit sensor is difficult enough. Trying to do it on the 7-8 bits that you get from a (consumer grade) sensor ... is going to be more difficult.

    But ... that's an interesting idea. I think that's worth a six-pack worth of funding.

    Did I get a first post? Are the trolls and the GNAA spammers asleep? Or, preferably, dieing slowly?

    --
    Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
    1. Re:Pretty cool ... by dns_server · · Score: 4, Informative

      One of the steps of building the kit is removing the IR filter from the webcam.

    2. Re:Pretty cool ... by thegarbz · · Score: 4, Informative

      I have converted consumer junk to remove IR sensors on many devices from simple webcams to high end DSLRs. It is simple.

      The hardest part about the process on cameras is working with tiny ribbon cables and sourcing replacement optics if you wish the resulting camera to operate again (since removing the filter completely will result in your camera becoming nearsighted.

      Neither of these are a problem with webcams, and the only issue you're likely to have is that some webcams have their filter glued onto the CCD rather than just placed on and retained with a small amount of pressure from the case.

  3. Spectrometers can get you tail! by Anonymous Coward · · Score: 5, Funny

    Back when I was in University in 2001 (U Waterloo - Independent Studies) one of the guys found a spectrometer for sale at the weekly physical plant surplus sale for fifty bucks so he just set it up in the IS lounge (which was in the middle of the Psych building) so people could come in and analyze whatever they wanted. It was great for inviting hippies in to charge up crystals with very specific wavelengths to increase harmonic resonance.

  4. I freeken love this. by Anonymous Coward · · Score: 4, Informative

    I did my PhD on a topic that involved building some gear related to spectroscopy. A good deal of my work involved cludging together optical parts from seemingly unrelated sources. As such I just love this sort of thing. Unfortunately I have to agree with the above commenter that the precision is just not going to be good enough from a webcam for real chemometric measurement. However with a little more investment the precision could be improved. The real difficulty will come from the need to calibrate the thing. You need to know exactly where each wavelength of interest is centred ** exactly** on the sensor at the time of measurement and this is not a trivial task. Unfortunately proper calibration is so often just not achieved... and that's not even beginning to consider the issues of background/ stay light, Johnson noise etc. I suppose this design could be used for crude detection like the article says rofl.

    1. Re:I freeken love this. by photonic · · Score: 4, Interesting

      Optics guy here too. I don't know a lot about spectroscopy, but I had to assemble a spectrometer for my thesis project. It was a pretty fancy imaging spectrometer (main element was a concave mirror and grating combined in one) and used a LN-cooled CCD as the sensor. This was not cheap stuff (~5000eu for the spectrometer and probably > 20000eu for the camera), but the operating principle is exactly the same as the DVD + webcam. The resolution was limited to around 1 nm due to the input slit, not sure if they could improve things by using a slit in this home-built device. I had to calibrate it from scratch, which was actually pretty easy: I borrowed some spectral lamps from the 1st year lab course and also used a HeNe-laser we had laying around. Choose a few of the big lines (which should all be known to better than 1 nm) and for each write down the pixel position of the line on the CCD. Perform low order (e.g. quadratic) polynomial fit and you are done calibrating. I don't know if there are some cheap spectral lamps that you could use at home, there is at least the yellow lines from the Sodium (?) street lightning. I agree with others that the resolution of these home built devices is probably too low to identify materials, but it is for sure a fun project.

      --
      karma police: arrest this man, he talks in maths; he buzzes like a fridge, he's like a detuned radio. [radiohead]
  5. Lots of work has been done here by Anonymous Coward · · Score: 5, Informative

    Lots of people have been working in this field. The most impressive results are achieved by the astronomy community. link It is possible to produce a home made spectrometer that gets useful results. Some of these are capable of resolution sufficient to identify chemicals. These are sophisticated and often use a peltier cell to cool the CCD in order to reduce noise. link

    I did a project whose aim was to produce a cheap spectrometer to match paint colors. link The problems I found were:

    1. Cheap webcams are quite noisy
    2. Cheap webcams are not at all linear
    3. For dark colors, sensitivity is a big problem
    4. The spectrum of the light source varies depending on which angle you view it from.
    5. Organizing the data is perhaps the biggest problem of all

    My own engineering trade-off was sensitivity vs. resolution. To get spectra for dark colored paints, I widened the slit which reduced resolution. That, as far as I could tell, was reasonable because I wasn't trying to identify chemicals and the spectra from paints weren't particularly sharp.

    The folks in TFA have a site where people can upload spectra. That's fine but a huge database of spectra is not too useful. The spectra have to be organized somehow. Here's an example. In fact the problem can be quite daunting