The Public Lab spectrometry project is an open source community effort to develop low-cost spectrometers for a range of purposes. All open spectrometry hardware and software efforts are welcome here!
Join in by:
- Reading about goals and asking great questions
- Building a basic spectrometer using one of our starter kits
- Trying (and critiquing) our community-made how-to guides
- Posting your own how-to guides and mods
- Building on others’ work; hack and remix the kits to refine and expand them
- Submit your improvements for inclusion in an upcoming starter kit release or add-on
- Serving on a Research Review Group for a 3 month period
This is a list of community-generated guides for experiments using your spectrometry setup (either a starter kit or a modded design) toward specific applications. Some may be more reproduced -- or reproducible -- than others. Try them out to build your skills, and help improve them by leaving comments.
|Wavelength-calibrate with a Compact Fluorescent Blub (CFL)||@warren||10 m||-||150 replications Try It||X replications|
|Scan sunlight to see Fraunhofer lines||@cfastie||10 m||-||80 replications||X replications|
|Compare different concentrations in a liquid sample (Beer’s Law, absorption)||@straylight||4 h||easy||0 replications Try it||X replications|
|Compare milk fat percentages||@wagnerc4||easy||0 replications Try it||X replications||X reviews|
|Compare blends of olive and peanut oil||@ygstc||3 h||moderate||0 replications Try it||X replications|
|Extract samples (tomato) with ethanol||@cfastie||2 h||easy||0 replications Try it||X replications | X reviews|
|Detect presence of sugar in beverages (wine)||@ygstc||2 hr||easy||0 replications Try it||X replications|
|Oil testing||@gretchengehrke||2 h||moderate||20 replications Try it||X replications|
|_(draft) Determine presence of organophosphate or carbamate pesticides||@silverhammer||5 hr||difficult||0 replications Try it||X replications|
|(draft) Collect and concentrate oil sheen||@matej||6 h||difficult||1 replication Try it||X replications|
|(requested) Determine effects of weathering on oil samples||-||-||difficult||-||-|
Guides should include a materials list and a step-by-step construction guide with photo documentation. See an example.
Have you added to your starter kit, improved it, or redesigned it? Show others how to take it to the next level by posting a build guide here:
|Oil Testing Kit (fluorescence, cuvette frame)||multiple||6 h||moderate||0 builds Build it||0 reviews|
|“Ebert” mod||@cfastie||4 h||easy||0 builds Build it||3 reviews|
|Plab3 spectrometer upgrade prototype||@stoft||13 h||difficult||0 builds Build it||0 reviews|
|Oil Testing Kit Proto 3||@stoft||4 h||difficult||0 builds Build it||0 reviews|
Mods should include a parts list and a step-by-step construction guide with photo documentation. See an example.
There’s a lot going on in open source spectrometry -- if you’ve developed another open source design you’d like to show others how to construct, post it here!
Public Lab’s Kits initiative offers several starter kits, including many of the basic components, and instructions for constructing a basic visible light spectrometer. The point of the kits is to provide a shared reference design for building experimental setups onto.
- The Desktop Spectrometry Starter Kit (now at version 3.0), is our most recent “reference design” incorporating some community improvements while balancing low cost and relative ease of construction. We have not yet met all our intended goals for this design, which is still at an exploratory phase: build on this design by adding a sample holder, attaching a light, or incorporating it into an experiment.
- New to spectrometry? You might like to try the Papercraft Spectrometry Starter Kit, a $10 foldable spectrometer which you can attach to a smartphone or webcam. It’s made of paper to reduce cost and complexity, and is mainly intended as an “introductory” or educational kit.
Using spectral data
Overview of spectra, calibration, units, comparison, and fluorescence/absorption/… Using the spectrometer with the https://spectralworkbench.org interface, spectral data is recorded, which includes qualitative light intensity at specific wavelengths of light. Data is presented visually in a plot with light intensity as a function of wavelength, ranging from 400 to 700 nm. By creating “sets” of multiple spectra, you can visually assess the similarities and differences between the spectra, although it cannot be used to compare the color of substances.
Same, remix, or expansion of existing docs.
Spectral data can be analyzed with https://spectralworkbench.org to create spectra plots, find centers of emissions plots, and find similar spectra. Data also can be exported to graphing programs such as Plotly, Gephi, or MatLab for further analysis and visualization.
How does this compare to a lab instrument?
The Desktop Spectrometry Starter Kit is only one part in an experimental setup, and the following shows where it fits in an overall diagram of a lab spectrometric setup:
[ Analysis computer ] [ Spectrometer ] = || [ Sample container ] || = [ Light source ]
[ Extraction system ] [ Sample storage ] [ Sample collection equipment ]
Many commercially available spectrometers are UV/Vis, meaning they have dynamic ranges from UV (~200nm) through the visible range and often into near infrared (~900+ nm). If interested in fluorescence specifically, a UV/Vis spectrometer may be important because many molecules respond to excitation wavelengths in the UV range. The Public Lab spectrometer only operates in the visible range (~400-700 nm). For visible range spectrometers, a commercially available product from Cole Parmer has a range from 335 to 1000 nm: http://www.coleparmer.com/Product/Cole_Parmer_Visible_spectrophotometer_335_to_1000_nm_wavelength_range_analog_output/UX-83055-10