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).

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

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

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

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Version 4.0 will be released very soon and is a much more refined design. You can read more about it here: 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: publiclaboratory.org/tool/spectrometer

License: CERN OHL v1.1 Public Lab contributors


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fast_edo on Feb 20, 2013 said:

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

BradDudenhoffer on Feb 21, 2013 said:

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

azuro on Feb 17, 2013 said:

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

Vise on Feb 17, 2013 said:

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!

BradDudenhoffer on Feb 17, 2013 said:

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/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.

laird on Feb 14, 2013 said:

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

jywarren on Feb 13, 2013 said:

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

BradDudenhoffer on Feb 13, 2013 said:

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.

owenscenic on Feb 13, 2013 said:

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

ecafruoy on Feb 13, 2013 said:

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.


BradDudenhoffer on Feb 13, 2013 said:

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.

bre on Feb 13, 2013 said:


BradDudenhoffer on Feb 13, 2013 said:

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