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Chemists use expensive tools called spectrometers (there are several kinds) to analyze unknown solid or liquid samples. We are working on a cheap version which we hope to use to identify oil contamination in water and soil, as well as a range of other possible toxins.
Spectrometers can also be used to identify species of plants or crop diseases, assess plumes from smokestacks, and have many other applications.
What we perceive as a single color consists of multiple blended colors- just as green paint can be made from mixing yellow and blue paint. A spectrometer is a device that splits light into the various colors it is composed of, which we otherwise cannot distinguish with the naked eye. By viewing a substance through a spectrometer, one can distinguish the exact mixture of colors, which correspond to specific wavelengths of light, that make up the perceived color of the sample.
Make a spectrometer
Buy a kit now »
The PLOTS spectrometer is a Do-it-Yourself tool made from simple materials:
- 4 1/8" x 8 3/8" stiff black card paper
- a clean DVD-R
- a webcam
- velcro, dark tape, a box cutter/x-acto knife
The DVD's tightly packed grooves act as a diffraction grating -- basically a prism. When light enters, the different wavelengths of light are bent to different degrees, forming a rainbow -- a spectrum.
The above link offers step-by-step instructions on making your own spectrometer. This design is released under the CERN Open Hardware License 1.1 (read agreement here). It features:
- around 400-900 nanometer range, maybe wider (what you can see with the naked eye, plus some infrared)
- 5-10 nm spectral resolution
- 20-30 samples per second
- ~ $10 in materials
- < 1 hour construction time
- open-source software
Though these specs look pretty good, they still need to be compared rigorously with a traditional laboratory spectrometer. Are you interested in trying it?
Using your spectrometer
One group of toxins common to fossil fuel contamination are PAHs, polycyclic aromatic hydrocarbons, which are generally carcinogenic. We're trying to develop a step-by-step experimental procedure to prepare a soil or water sample, shine a full-spectrum light (like a halogen lamp) through it, and detect the missing wavelengths.
If you're interested, please chip in to develop and document a consistent way to read samples here:
Online spectral analysis
Along with the physical tool itself, the PLOTS team has also developed a software suite and online spectrum sharing website which allows anyone to upload their data and work with others to try to interpret it. These tools are early prototypes and we're looking for help developing them.
Finally, a FAQ with some insights about actually using your spectrometer can be found here:
This is an early-stage, speculative project, but our goals include:
- Identify a contaminant in a sample, like a polycyclic aromatic hydrocarbon -- i.e. naphthalene, anthracene or tetracene. Tetracene has absorption bands well into the visible range.
- Identify a plant species by its spectrum. (see this helpful paper by Zomer et al) Or perhaps a mineral, using the ASTER spectral library
- Try to identify something in a smokestack plume, like a refinery plume
Several older designs have been documented on this site. Guides have been made showing you how to make some of these; they include:
- plots-spectrometer-guide-small.pdf - by the PLOTS team for our workshop at the Whitney Museum
- Make a Spectrometer.pdf - by Alex McCarthy
|Make a Spectrometer.pdf||794.23 KB|
On Jun 18, The creator of [GrassrootsMapping.org](http://grassrootsmapping.org) and co-founder and Research Director for the Public Laboratory for Open Technology and Science, Jeff designs mapping and civic science tools and professionally flies balloons and kites. Notable software he has created include [the vector-mapping framework Cartagen](http://cartagen.org) and [orthorectification tool MapKnitter](http://mapknitter.org), as well as open spectral database and toolkit [Spectral Workbench](http://spectralworkbench.org). He is a fellow at MIT's [Center for Civic Media](http://civic.mit.edu), on the advisory board of [Personal Democracy Media's WeGov](http://techpresident.com/topics/wegov) and an advocate of open source software, hardware, and data. He co-founded Vestal Design, a graphic/interaction design firm in 2004, and directed the Cut&Paste Labs project, a year-long series of workshops on opensource tools and web design in 2006-7 with Lima designer Diego Rotalde. Jeff holds an MS from MIT and a BA in Architecture from Yale University, and spent much of that time working with artist/technologist Natalie Jeremijenko, building robotic dogs and stuff. To find out more, visit Unterbahn.com. * https://github.com/jywarren * http://unterbahn.com * http://unterbahn.com/thesis/ updated Page: About Public Lab
Adam-Griffith commented on Adam-Griffith's Note "Folly Beach, SC - a detailed look at a $3 million beach "restoration"" on Jun Tuesday
On Jun 5, Adam D. Griffith is the Director of the Rivercane Restoration Project through the Program for the Study of Developed Shorelines (PSDS) at Western Carolina University. He received a BS degree in Biology from Roanoke College in 1999 (Omicron Delta Kappa) and was subsequently accepted to Teach for America. He taught 6th grade science in the Houston Independent School District in Texas for three years before becoming a kayak instructor taking him on numerous trips to the beaches of the United States, Panama, and Europe. He received his MS degree in Biology from Western Carolina University in 2008 studying the native bamboo Arundinaria gigantea. Since 2008, he has been a research scientist at PSDS where he launched coastalcare.org with the Santa Aguilla Foundation. He currently directs the communities and sea-level rise research. In 2011, he co-founded the Public Laboratory with 6 others by securing a $500,000 grant from the James S. and John L. Knight Foundation. As a result, his writings can be found on the PBS IdeaLab blog, publiclaboratory.org, and others. He has presented his research with the Public Laboratory across the United States, Mexico, and Europe. Selected Publications Tanner, B.R., Kinner, D.A., Griffith, A.D., Young, R.S. & Sorrell, L.M (2011). Presence of Arundinaria gigantea (river cane) on numerous non-wetland sites suggests improper ecological classification of the species. Wetlands Ecology and Management. 19(6): 521-532. Coburn, A.S., Griffith, A.D. & Young, R.S. (2010). Inventory of coastal engineering projects in coastal national parks. Natural Resource Technical Report NPS/NRPC/GRD/NRTR???2010/373. National Park Service, Fort Collins, Colorado. Griffith, A.D., Kinner, D.A., Tanner, B.R., Moore, A., Mathews, K.G. & Young, R.S. (2009). Nutrient and physical soil characteristics of rivercane (Arundinaria gigantea) stands, western North Carolina. Castanea. 74(3): 224-235. updated Page: Classification