Project – 2

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March 16, 2011

The primary element in both spectroscopes and spectrographs is a narrow slit oriented perpendicular to the direction in which the grating or prism spreads the light. As with a pinhole camera, the small aperture images the light source sharply along the spectrum’s axis, which keeps the spread of wavelengths distinct. Each image of the slit, in a slightly different color, is arrayed across the field of view in a wide spectrum image. If any wavelength is brighter or dimmer than the rest, it shows up, respectively, as a bright or dark line in the spectrum.

Although spectroscopes have always been easy to make, a homebrew recording spectrograph presented more of a challenge. Building your own spectrograph meant using microcontrollers and stepper motors to move diffraction gratings past a light sensor — many were planned, but few were actually built.

Today, digital cameras and online tools can turn a simple spectroscope into a laboratory-quality, high-resolution spectrograph. All it takes is a few plumbing parts and other inexpensive materials and less than an hour at your kitchen table.