Note: This is an older post of mine that needed some housecleaning (I updated my website and subsequently broke the links). This project hasn't been changed, but since I just got hold of a new RPi2, I may have to break out the Legos again.

I describe in a blog entry on my website how I went about building a basic visible spectrophotometer using the Wolfram Language, a Raspberry Pi, a few Legos and a variety of tutorials found on the web. The spectrometer uses a white-light LED as a source. A reflective grating made out of a CD is mounted on a 512 step stepper motor to get variable wavelengths and a photoresistor is used as the detector. The setup looks like this:



As with some of my other projects discussed in the Raspberry Pi forum, I am using MathLink and the WiringPi library to handle most of my GPIO communication with the RPi. Mathematica serves as a GUI to turn the source on/off, move the grating (and remember where the grating is positioned) and (naturally) plot and process the results:



It's not a terribly sophisticated interface - merely a palette with some buttons, but it does the trick. You'll see in the above image that there is much room for improvement with respect to my "spectra". The primary issues here are (a) my stepper motor only allows for about 32 steps across the visible spectrum and (b) the low-budget method for measuring the detector response results in a fair amount of noise. Still, (not shown) the reproducibility is decent given the lack of sophistication and the setup demonstrates how Wolfram/RPi can be used to make a basic instrument for learning and discovery.

In addition to posting some improvements to the instrument, I'm hoping to show how it can be used for some DIY science experiments - it would be great to see a WolfSpec derivative in a future science fair project...