Low Cost Spectrometry

Come for the replacement for the Spec 20 using low-cost computing. Stay for the further explorations of Python-based spectrometer solutions.

Spec 20 replacement

To address the failing Spec 20s in my department, I developed a replacement based on a Raspberry PI computer and a StellarNet spectrometer. It is written in Python for ease of modification. The initial design was published in the Journal of Chemical Education in 2021.
Navarre, E. C. Extensible Interface for a Compact Spectrophotometer for Teaching Molecular Absorption in the Undergraduate Laboratory. Journal of Chemical Education 2020, 97 (5), 1500–1503. https://doi.org/10.1021/acs.jchemed.9b01023.

The code can be found on Github

A bonus publication came from the characterization of the LEDs for the spectrophotometer. Surprisingly, no one had characterized them yet. We also characterized the impact of pulse-width modulation on the LED.
Navarre, E.C. Characterization of “cool” and “warm” white light-emitting diodes for low-cost spectrophotometry. Spectroscopy Letters, 2021, 54(8), 581–589. http://dx.doi.org/10.1080/00387010.2021.1963781

ETA software

The display system for the Spec 20 project is a useful way to access and display live spectrograph data. I modified that system to record 3 wavelengths so that we can implement the two-wavelength background correction method for atomic spectroscopy. The program required stable data acquisition intervals of 25 ms. We learned a lot about Python and Matplotlib speed issues.

Control of the tungsten filament power supply is integrated into the package.

The code can be found on Github