The State of Open Source Spectrometry

spectral_feat

For those of you that slept through chemistry in high school, spectrometry (also known as spectroscopy) is the process of measuring the spectrum of light that either passes through, or is reflected off, of an object.  As different chemicals and compounds have different spectral emission patterns, the wavelength of the light entering the spectrometer can be used to determine the makeup of the substance being tested.

To put it another way, looking at the light that comes through the substance it’s possible to determine it’s chemical components, and therefore, what it is.

This technology is incredibly useful, having applications in everything from the medical field to homeland security. Unfortunately, there are two things you need to perform spectrometry which have not previously been easy to get your hands on:

  1. An actual spectrometer
  2. A database of chemicals and their spectra

Until now, that is. The Public Laboratory for Open Technology and Science (PLOTS) has put together open source software and the plans to build your own low-cost spectrometer so that anyone in the world can dive into this fascinating field.

Spectral Workbench

The key to the entire project is “Spectral Workbench”, which is a site that allows users all over the world to submit, compare, and search spectra samples. By uploading the spectra results for known substances, the community can start building a database of chemicals and their spectral “fingerprints”.

Spectral Workbench is an absolutely incredible piece of software, and just oozes polish and professionalism. It would be forgiven if Spectral Workbench looked rough and utilitarian, but PLOTS decided to crank it up a little bit, and it definitely shows.

Spectra of various types of coffee

The source for Spectral Workbench is available on GitHub, released under the GPLv3. While you can download this software and run it locally on your own machine, it’s much easier to just access it via the site. Though it’s worth mentioning that uploading via the site itself is still considered something of a beta.

Spectrometer Hardware

Of course, this database of spectra is no use to us if we can’t easily collect our own. To that end, PLOTS is currently running a Kickstarter campaign to deliver everything from a papercraft spectrometer that tapes to the back of your smartphone to a full on desktop model suitable for hackerspaces and amateur laboratories.

The most popular option, priced at only $35, is a DIY spectrometer kit made from an old plastic VHS case and a webcam. While the construction isn’t particularly difficult, requiring little more than cutting and taping the materials together, there is a degree of finesse involved. Lines must be cut as close to perfectly straight as possible, and you’ll be fighting enemies such as internal reflections and light seepage the whole time. Still, even a person with zero technical ability will be able to complete the kit, which is important to drive up adoption rate.

Inside PLOTS simple spectrometer

The mobile version of the spectrometer is even more simplistic. The $10 version is simply some black material that you cut out into the appropriate shape. For $65 you can get an experimental “backpack” model, which is made of plastic and is considerably more rugged. It’s worth noting that, as of right now, only Android devices are supported for the mobile version of the Spectral Workshop software; though an iOS build is not out of the question depending on demand.

Unfortunately, without modification of the smartphone’s camera, both of these models are only able to operate within the visual spectrum of light. Getting full spectrum measurements would require the removal of the phone’s infrared filter, which would then ruin it’s normal camera capabilities. Of course, if the goal is to construct a mobile spectrometer, an older Android device could have it’s camera permanently modified for the purposes of being a low-cost scientific instrument.

Limitless Uses

Bringing the cost of spectrometry down this low could have some profound effects all over the world, as the applications for this technology are nearly limitless.

This kit could analyze drinking water, identify possibly hazardous substances, assist in medical tests, etc. A cheap spectrometer, a laptop, and an open database of spectra could completely change the way of life for people in impoverished parts of the world.

It allows the individual to do everything from analyze so called “green” products for hazardous chemicals to refining the recipes for homebrew beer and wine. Compare different brands of detergent to see which one really offers the best value. As time goes on and more people begin submitting spectra, we’ll see more and more practical applications for this process.

The ability to examine, reproduce, and improve is at the core of the open source philosophy. Being able to bring that idea into the physical world, being able to literally see inside of a substance to see what its principle components are, is perhaps the ultimate realization of open source.


Tom Nardi

Tom is a Network Engineer with focus on GNU/Linux and open source software. He is a frequent submitter to "2600", and maintains a personal site of his projects and areas of research at: www.digifail.com .

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