I would like to build a home made spectrometer like it's describing here:


How can I improve this spectrometer? A prism from an old binocular? How would I enhance this spectrometer to improve accuracy and clarity?

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The resulting images from this spectrometer are promising.

A first starting point might to use something better than a cereal box. Preferably a box which is completely black inside, this improves the contrast of the image.

A second step could be to replace the CD by a diffraction grating and a mirror which are both not curved, the input slit could be replaced by something, where you can vary the distance with screws.

For any kind of 'real' science you might want to measure the output spectra. So instead of projecting it onto the nearest surface a fixed paper screen might be nice, where you can draw a scale for the individual wavelengths, e.g. to identify different elements (e.g., Na-lamps at night, fluorescent light bulbs).

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  • $\begingroup$ Can you elaborate a little more on diffraction grating and a mirror? The rest of the answer is really great. Thank you. $\endgroup$ – whitefleaCH Jun 13 '12 at 15:32
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    $\begingroup$ The CD in the linked instruction is already a kind of diffraction grating, the aluminium layer acts as a reflecting mirror. One simple idea is to replace the CD by a DVD, which has a much smaller track distance. The problem with both though is, that the tracks are curved, so depending on the length of your slit some light reaches the grating at a different angle and this reduces your resolution. A straight grating might be an improvement and is not expensive to buy. $\endgroup$ – Alexander Jun 13 '12 at 16:31


Since you will be looking at light sources, try for a even smaller slit, using razor blades. Smaller slit increases resolution, but decreases intensity of lines.


The DVD has 1350 lines per mm, that's gives a good dispersion. Prism will spread the spectra more,and stand alone emission lines will be more spaced.So yes it improves accuracy(spectral resolution)

Cool Idea:

Rather, You can use the prism to reflect the spectra light to view at another angle which will be more comfortable (using Total internal reflection). You can etch a wavelength scale on the glass to identify wavelengths.

You did a Good Job. High five.

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