Want to talk about soil? Join us for Open Call every Tuesday until Mar. 30 and our kick-off call on this topic on Feb. 2! Click here for details on how to join!

Public Lab Research note

This is an upgrade for foldable-spec. Try building it and report back how it goes.

Silhouette cut Public Lab Mobile spectrometer v2

by briandegger | December 11, 2015 15:59 11 Dec 15:59 | #12497 | #12497


What I wanted to do

Make a plotter knife cut version of the public lab spectrometer

My attempt and results

Seems to work (see attached pdf)

Questions and next steps

Seems to work (see attached pdf)

Why I'm interested]

wanted an easier way of making the cardboard version. Silhouette-cut-Public-Lab-Mobile-spectrometer.pdf

I made this Help out by offering feedback!

People who made this (0)

None yet. Be the first to post one!


I love it! It looks great, and I have a Cameo too. I want to try cutting it into a plastic sheet, too!

Reply to this comment...

Thanks for this clever design! I made this using my Portrait and the only cardstock I had handy: pink. After assembly, I covered the outside in black electrical tape to block light. I tried to follow the instructions to make the grating from a DVD-R, and I think it worked.

However, I don't see a spectrum! Since I'm a complete noob at this, I don't know where to look or what to look for. I have looked all over this (brilliant) site, but can't seem to find a picture of anyone using this device with the naked eye. At what angle and where should I look for the spectrum? I've tried pointing the slit at everything from the sun to a candle. Looking thru the grating, I can see the light slot, I can see the light hitting the inside surface of the tube (as a nice line), but I don't see a spectrum. Can you give me some direction? Thanks for any help.

Is this a question? Click here to post it to the Questions page.

Reply to this comment...

Sorry, i was holidazing! Can you upload a pic of your build, so we can help debug? You kind of have to look perpendicular to the grating's surface, but pointing the slit towards a diffuse but bright light source -- like a white wall under a fluorescent light, or the sky -- will help. That way, for starters, you don't have to align things as much.

Is this a question? Click here to post it to the Questions page.

Reply to this comment...

Not sure if that helps or not. Here is a fundamental question I'm unclear about. Knowing that the diffraction lines on the DVD are parallel to the rim, should the slit be parallel or perpendicular to the rim? (To be clear, I consider "parallel" to mean along a tangent to the rim, and "perpendicular" to be along a radial line from the rim to the center of the DVD.) Also, does it matter which side of the dvd (the clear part, after splitting it) is nearest the slot? Finally, where should my eye be? Right next to the opening of the spectrometer, or at a distance? Thanks. I'll take some pictures and post them if the answers to these questions don't help.

Is this a question? Click here to post it to the Questions page.

Reply to this comment...

The entrance slit should be parallel to the grating lines. I don't recall that anyone found that spectral quality is improved with one side or the other of the DVD toward the slit. I think the shape of the diffraction pattern changes some depending on how the DVD piece is rotated (lines concave up vs down). You should see the diffraction pattern with your eye close to the grating.


Reply to this comment...

That helps a ton! Not only do I see the spectra, I can even photograph them. Here are some shots of what I built, and a spectrum from the cloudy sky (the sun) and a ceiling light (halogen). Now that I know how to find the spectra, I'll work on improving the images, etc. I'll also build a nice black one.

Thanks for your patience and guidance! spectrom1.jpg





Reply to this comment...

Login to comment.