Public Lab Research note

Introducing the Public Lab Smartphone Spectrometer

by warren | November 15, 2013 20:49 15 Nov 20:49 | #9786 | #9786

At long last, we've started shipping the Smartphone Spectrometer, formerly called the "Backpack Spectrometer" -- and you can order a kit today (shipping begins by the end of the month):

As you can see above, they came out minimal but nice-looking, and they're quite sturdy. We ultimately went with an optically printed slit which gives you a fantastically narrow and consistent aperture and excellent resolution as a result. These are designed to work with most smartphones, from Android to iOS devices (even tablets) although if your phone has a curvy back, you may need to use more of the provided black foam tape to reduce light leakage. (Yes, that's a Firefox OS phone pictured above.)



The web-based software runs on a variety of browsers, and we'd love to see someone test it on iOS with the Bowser Browser. We're still working on a native app for iOS, and expanding the offline- and mobile-friendly parts of the site; you may get more mileage doing the analysis bits on a desktop computer.


Assembled, though without the diffraction grating installed.

Attaching it to your phone

We went through many iterations of attachment techniques, but ultimately we opted for flexibility. The kit includes several different adhesives which can be used to permanently or temporarily (with Glue Dots!) attach the device to the back of your phone or tablet. What's worked best for me is to get a matte black case for a given phone, and permanently attach the spectrometer to the case. Then it's quite cleanly and permanently connected, but you can still get your phone out and use it normally. Some of you may want a spectrometer permanently attached to your phone... :-P


The device also has a screw hole designed for a 1/4" camera mount, so you can attach it to a tripod, maybe for monitoring something far away like a gas refinery flare. Finally, it also includes a "Public Lab" mini-screwdriver. I swear, it was actually cheaper to get those with a logo on them than without.

Expansion packs

We designed the aperture (with help from Brad Dudenhoffer) to fit one standard 1cm x 1cm cuvette full of some sample you've collected, but it's also set up to be attached to experimental setups which might include calibrated lights, lasers, or what have you. We've definitely thought of:

  • telescope adapters
  • controlled ultraviolet lighting
  • connecting to a transparent pipe for in-line spectrometry monitoring of a liquid
  • mounting these to DSLR cameras for extreme hi-res spectra, and long exposures

But the sky's the limit, this is open hardware, so get 3d printing and try things out!

Congratulations to Mathew Lippincott who led the design, Brad Dudenhoffer who assisted, and Noah Hochman, who packed and shipped these with Mathew. And a big thanks to all our Kickstarter backers who made this possible and were patient for the longest time before we got these out the door.


Design files

This being open hardware (CERN OHL 1.1), here are the files:

These are also on Thingiverse:

And here is a more 3D-printable version by Brad Dudenhoffer:

Order a 3D print on Shapeways here:

And don't forget our other spectrometers:


Is the spectral display actually saved. Is there a way to access the spectral data (spectral display) for dropping into Excel or something like that for further analysis and comparison?

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yes! there are CSV, JSON and XML download links on each spectrum page at

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Thank you @warren for this great project!

I am planning to use its basics to build a similar spectrometer and I want to ask you a few questions:

  1. What type of diffraction grating I should choose for best results - 500, 530 or 1000 lines/mm?

  2. The diffraction grating I can get will be only 35x24mm. Does it mean that the inside width of the "dark chamber" should be 35 mm as well?

  3. Important question about the angle of diffraction grating positioned relative to bottom side in your model. Can you explain angle you choose and give some advice for right geometry of my own device?

Will appreciate your answers very much.

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Hmm, I actually think DVDs are some of the highest quality gratings available, esp. if alcohol is used to clean the dye off. But you'd have to ask on the spectrometry list about the exact spacing; it's been discussed various times but I don't have a link on hand. Higher is better, generally.

Here are some links on angle:

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