Ever play with a prism? When sunlight strikes the prism, it gets split into a rainbow of colors. Prisms un-mix the light into its different wavelengths (which you see as different colors). Diffraction gratings are tiny prisms stacked together.

When light passes through a diffraction grating, it splits (diffracts) the light into several beams traveling at different directions. If you’ve ever seen the ‘iridescence’ of a soap bubble, an insect shell, or on a pearl, you’ve seen nature’s diffraction gratings.

Scientist use these things to split incoming light so they can figure out what fuels a distant star is burning. When hydrogen burns, it gives off light, but not in all the colors of the rainbow, only very specific colors in red and blue. It’s like hydrogen’s own personal fingerprint, or light signature.

While this spectrometer isn't powerful enough to split starlight, it's perfect for using with the lights in your house, and even with an outdoor campfire.  Next time you're out on the town after dark, bring this with you to peek different types of lights - you'll be amazed how different they really are. You can use this spectrometer with your Colored Campfire Experiment also.

SPECIAL NOTE: This instrument is NOT for looking at the sun. Do NOT look directly at the sun. But you can point the tube at a sheet of paper that has the the sun’s reflected light on it.

Here's what you do:

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Comments

6 Responses to “Calibrated Spectrometer”

  1. Aurora Lipper says:

    You’re welcome. Having the double axis diffraction grating explains why you are seeing multiple images of the ruler. That diffraction grating won’t work for this experiment because it is essentially splitting the light ing two different directions. So, you will indeed need to get a linear diffraction grating such as the one recommended on this page.

  2. katie_johnson says:

    Thank you for your reply. We have the same brand, but our diffraction grating is the 13,500 double axis diffraction grating. Can we make that work? Or, will we need to order the one you suggested? We will play with the width of the space between razor blades, also.

  3. Aurora Lipper says:

    If you’re seeing multiple images of the ruler, this usually has to do with the diffraction grating you are using. I just updated the link for the diffraction grating. This link provides one that has 500 lines. Do you know how many lines your diffraction grating has?

    To make the colors as visible as possible, try moving one of the razor blades to make the slit smaller or wider.

  4. katie_johnson says:

    We made the spectrometer just like you said, but, the ruler looks really fuzzy and is very difficult to read. It splits up into 3 rulers like when you put your eyes out of focus. you can see some colors, but, it is so difficult to read and so split that we don’t know what we are looking at and we certainly can’t see the measurements to read anything. Any suggestions?

  5. Yes, that’s perfect. Just be sure to calibrate precisely and it will work well for you.

  6. littlelisa94 says:

    Can this work with a double-axis diffraction grating? Are any changes in the construction needed?