A fantastic invention: Jie Bao (of Tsinghua University) and Moungi Bawendi (of MIT) have invented an optical spectrometer small and cheap enough to attach to a cell phone, which can nonetheless perform comparably well to serious professional equipment.
Spectrometers are amazingly useful devices: they simply break light up through a prism, and report on how bright the light is in each frequency. That lets you recognize chemicals (each molecule has a distinctive color "fingerprint"), measure temperature (when you heat an object, it glows with a spectrum that's a simple function of temperature), and even measure the speed of objects. (If you know something's color when it's still, its colors in motion are shifted by the Doppler effect, just like an approaching siren's pitch goes up and a receding one goes down. The fingerprints of chemical colors give you an excellent reference point for that)
Bao and Bawendi's device is completely different from traditional spectrometers: Rather than using a prism and precision optics, they use an array of 195 carefully chosen inks and a CCD light sensor. The result is rugged and cheap – a few dollars, instead of a few hundred or thousand.
This is a tool that could revolutionize all sorts of devices; the authors give an example of a tool that could identify skin cancer just by pointing at it. (Cancers contain specific chemicals which produce specific optical fingerprints, after all!)
And more to the point, it's neat.
Dear Drs. Bao and Bawendi: TAKE MY MONEY!
Via +California Academy of Sciences