PublicLaboratory Mobile Spectrometer v3.0

by BradDudenhoffer, published

PublicLaboratory Mobile Spectrometer v3.0 by BradDudenhoffer Feb 13, 2013

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Here it is. Version 3.0 of the PublicLaboratory.org mobile spectrometer. This spectrometer is a scientific tool that straps onto an Android or iOS phone, tablet, or any camera capable of focusing very close (macro-mode) and allows you to collect spectra. Why would you want one? You can use it to identify the elemental composition of things (light bulbs, olive oil, beer, etc) based on the colors of light they emit. You can even use it to monitor your home brewing progress (http://bit.ly/Xyor6B).


Version 4.0 will be released very soon and is a much more refined design. You can read more about it here: http://publiclaboratory.org/notes/braddudenhoffer/2-11-2013/evolution-plots-smartphone-spectrometer-0

Assembly is much easier than earlier models.

  1. Print the two parts (the base and the body either plain or with the logo)
  2. Attach a film grating to the upper side of the base
  3. Secure the base to the body with hot glue, tape, or if you print with ABS by solvent welding it together with acetone.
  4. Mount it to your phone
  5. Use spectralworkbench.org to calibrate, save, and share your spectra. There is a native iOS app in the works but I can't say for sure when it will be released.

If you use an extrusion printer such as a Mendel you will probably need to print with support if you want the text to show up. If anybody wants a version without the text, let me know and I will post it ASAP. Also, make sure you have your printer tuned up to print bridges and overhangs very well, because this thing is basically one huge overhang. I have successfully printed it on a MendelMax. The walls are little thinner than is ideal but that will be fixed in the next version :).

All parts have been NetFabbed and verified.
This is the grating I have used for the prototype. It is the linear style with 1000lines per mm: tinyurl.com/9tjrz8r . You can also use the film off of a CD, DVD, or BluRay as seen here: http://publiclaboratory.org/tool/spectrometer

License: CERN OHL v1.1 Public Lab contributors

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This is amazing. Going to try to print this at home. Can you let me know what software I should get for Android? I searched around but couldn't find one.


Thingiverse won't let me post a link but google spectralworkbench and you will find it. The rest of the spectrometry info is over at thepubliclab.


Great work. Just printed one, my first print on my printer so I must have thought it was good :-)

Just one thing where exactly do you put the diffraction grating?

"Attach a film grating to the upper side of the base" is a bit vague for me, sorry. Are there any pics?

The diffraction grating is sandwiched between the base and the body.

I need this for a S3 to check beer!!!! come on android!

Good news! The mounting plate was designed to accommodate the center camera of the S3 :).

This is incredibly cool! Thank you very much for sharing.

hi! your project is amazing!

i printed with my mendelmax with green PLA (translucent) then covered with black tape. I have some problem because the lines are not in the middle of the picture, but they are cutted on the upper side.

I'm projecting a derivate that can fit better with my phone, there are dimensional limitations or i can do it smaller?
Thanks in advance!

Hello Vise. Thank you for trying out the spectrometer. What type of phone are you using? The spectra don't need to be perfectly centered as long as they are consistent. The analysis software uses a row of the camera sensor that is only a couple pixels wide so cutting the top off won't affect anything. If you want one to fit a specific model of phone you might want to take a look at version 2.3 (http://www.thingiverse.com/thing:28100)http://www.thingiverse.com/thi.... It is about the same length but half as wide. The length does have a strong effect on geometry and spectrum spread. This one is about as short as is usable without some fancy lenses, mirrors, and grating. Phones with a larger/wider lens would benefit from a longer distance from the slit to the sensor.

PLOTS Spectrometer, ChemistryDude Edition V2.3

Thanks for the fast reply! :) I'm very intrested to this project!

i'm using an iphone4, and i'm sure that some lines are cutted from the picture because i compared with the spare dvd film and two or more lines are missing.

I thing it can be printed better (expecially for the light slot), using the lateral flat side as base.

The grating you linked in the description has a better quality than the dvd film?

Ps: sorry for my bad english, i hope u can understand :)

Interesting. Is it possible that the base is covering part of your camera? Try moving the spectrometer around on the back of your phone and see if the lines ever show up.

The slit has been my biggest issue with this design. The previous design printed the end as a solid piece and then required the builder to cut the slit with a razor blade or saw. It works better, but adds a couple more steps. You could always cut a slit in a piece of thin aluminum or steel and slide it into the end of this design. That should allow better separation of spectral peaks as well as sharper peaks. Rotating the model onto it's side before printing would definitely help with the slit but then I worry about the huge bridge that would be required to print the other edge. Maybe if you split it vertically, print both sides flat, and then glue them together? I'll upload a split model today.

The resolution of the grating I liked to is not significantly better than DVD film but it does make straight spectral lines. If you use the spectralworkbench software then it doesn't matter but other some other analytical software packages require straight lines. If you don't need straight lines, then blu-ray film works even better than DVD film.

p.s. No problems. Your English is excellent.

It's great to see this here. I backed this on Kickstarter, and it'll be fun to print my own. Super cool!

By the way - if anyone prints it, please post photos here or at http://PublicLaboratory.orgPublicLaboratory.org, it'd be great to see them!

For absorbance scpectroscopy just about any light source can be used as long as it is consistent. White LEDs work well enough but tungsten lamps are generally better. Emission spectroscopy can also be done with just about any light source but lasers are becoming more popular than other techniques. In general, you excite with one wavelength of light wand watch for changes in another. Metals can be tough. You need to superheat them if you want to measure them directly. There are reagents which quantitatively great with specific metals and then have a color change or shift which could be used with this spectrometer.

My tricorder dreams are getting closer to reality....

I've had some experience with inductively coupled plasma optical emission spectroscopy for detecting trace metals in a water sample. (the samples would need to go thru an acid digestion step)
I wonder if this process could be scaled down to a handheld unit? However the argon gas and the strong magnetic field needed to create the plasma may be speed bumps to say the least. Still... the processing power of a smartphone could be applied to the process in some way.


Having had an ICP apart, I doubt thee will be a portable version any time soon. LIBS is the future for that type of thing. There are already handheld LIBS systems on the market for ~US$30,000. They use very little or no shielding gas and a pulsed laser to vaporize minute aliquots of the material being tested.

Thank you. It has been a heck of a team effort with Jeffrey and the amazing folks at http://publiclaboratory.orgpubliclaboratory.org