##Purpose##
Chemists use [expensive tools called spectrometers](/notes/warren/11-30-2011/visible-light-spectrometer-2660-4-7nm-bandwidth) (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's spectrometry?###
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 your own inexpensive spectrometer###
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.
Learn how to make one here: [Video spectrometer construction](/wiki/video-spectrometer-construction)
This design is released under the CERN Open Hardware License 1.1 (read agreement here). It features:
* around 400-900 nanometer range, maybe wider
* 5-10 nm spectral resolution
* 20-30 samples per second
* ~ $10 in materials
* < 1 hour construction time
* Mac and Linux compatible, should work on Windows but untested
* [open-source software](/wiki/spectral-workbench)
###Usage###
One group of toxins common to fossil fuel contamination are PAHs, polycyclic aromatic hydrocarbons, which are generally carcinogenic.
...
###Online spectral analysis###
Along with the physical tool itself, the PLOTS team has also developed an online application which allows anyone to upload a spectrum photographed with a digital camera to the website, and use the online tool to analyze the intensity of the spectrum. The intensity of the spectrum at each wavelength adds a second dimension to the data, allowing for more accurate comparisons to known spectrums.
Another tutorial:
###Resources, Downloads, FAQ###
Access the online tool at: https://spectralworkbench.org
* [Tube spectrometer](/wiki/tube-spectrometer)
Several guides have been made showing you how to make a spectrometer.
Make a Spectrometer - Alex McCarthy
And another prepared by the PLOTS team for our workshop at the Whitney Museum, here:
plots-spectrometer-guide-small.pdf
Finally, a FAQ with some insights about actually *using* your spectrometer can be found here:
[Spectrometer FAQ](http://www.publiclaboratory.org/wiki/spectrometer-faq)
###Make your own inexpensive spectrometer###
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.
Learn how to make one here: [Video spectrometer construction](/wiki/video-spectrometer-construction)
This design is released under the CERN Open Hardware License 1.1 (read agreement here). It features:
* around 400-900 nanometer range, maybe wider
* 5-10 nm spectral resolution
* 20-30 samples per second
* ~ $10 in materials
* < 1 hour construction time
* Mac and Linux compatible, should work on Windows but untested
* [open-source software](/wiki/spectral-workbench)
###Usage###
One group of toxins common to fossil fuel contamination are PAHs, polycyclic aromatic hydrocarbons, which are generally carcinogenic.
...
###Online spectral analysis###
Along with the physical tool itself, the PLOTS team has also developed an online application which allows anyone to upload a spectrum photographed with a digital camera to the website, and use the online tool to analyze the intensity of the spectrum. The intensity of the spectrum at each wavelength adds a second dimension to the data, allowing for more accurate comparisons to known spectrums.
Another tutorial:
###Resources, Downloads, FAQ###
Access the online tool at: https://spectralworkbench.org
* [Tube spectrometer](/wiki/tube-spectrometer)
Several guides have been made showing you how to make a spectrometer.
Make a Spectrometer - Alex McCarthy
And another prepared by the PLOTS team for our workshop at the Whitney Museum, here:
plots-spectrometer-guide-small.pdf
Finally, a FAQ with some insights about actually *using* your spectrometer can be found here:
[Spectrometer FAQ](http://www.publiclaboratory.org/wiki/spectrometer-faq)