##How to build and use a spectrometer (draft)## Collect some samples from the beach, water and sediment and solids, and build a spectrometer, and try taking some photos through it. They're really pretty easy to make out of PVC tubes, and I will upload some sketches and so forth soon. So the theory is that if you shine strong UV light ([buy here](http://www.google.com/search?client=safari&rls=en&q=uv+light&ie=UTF-8&oe=UTF-8#q=uv+light&hl=en&client=safari&rls=en&prmd=ivns&source=univ&tbs=shop:1&tbo=u&ei=RbJJTd-YJcaqlAfzz90f&sa=X&oi=product_result_group&ct=title&resnum=3&ved=0CFcQrQQwAg&biw=1159&bih=661&fp=1)) on the samples, they should glow in a very specific color. that should make a spike at a certain point on the spectrum, though you may need to compare it with a spectrum taken *without* UV, to see the spike. The spike *should* be visible in normal light, so any camera should do. Even just building a spectrometer is a good experience and if we continue to follow up on spectrometer research the skills and nuances of building one will come in handy even if we can't identify PAHs with them. ###Additional notes on spectrometry for the [spectrometer tool](/tool/spectrometer)###: Color algorithms to automatically recognize wavelengths: * http://stackoverflow.com/questions/1678457/best-algorithm-for-matching-colours/1678498 * http://stackoverflow.com/questions/1720528/what-is-the-best-argorithm-for-finding-the-closest-color-in-an-array-to-another-c * http://www.velocityreviews.com/forums/t430790-rgb-wavelength-intensity.html * http://codingmess.blogspot.com/2009/05/conversion-of-wavelength-in-nanometers.html=