Transforming Pixels into Spectra: The Educational Journey of Recycling an Old Optical System

The academic community increasingly embraces the possibilities offered by the Maker movement, with a notable rise in the creation of homemade instruments, particularly in the field of spectroscopy. These instruments are being leveraged to enhance engagement in classes and educational projects. Most of these homemade instruments designed for educational purposes rely on simplified 3D-printed components and/or adapted materials, such as compact discs used as diffraction gratings. This article proposes yet another solution by recycling an optical system from an old liquid chromatograph decommissioned due to obsolete communication protocols. The entire instrument’s optical system is used, and the original photodiode array (PDA) was replaced by a modern PDA that could be easily controlled by Arduino and a user interface developed for this intent. A flowchart illustrating the interface operations related to absorbance calculations is presented, followed by a discussion on how the shape of the acquired spectra may be influenced by positioning of the sensor. The raw data obtained in this work can also be utilized to teach concepts related to dark current, baseline correction, instrument calibration, and absorbance. The visible spectra of several substances from the resultant instrument are presented and compared with those of a commercial benchtop spectrophotometer. The approach described here can inspire the recovery and recycling of other outdated instruments, providing opportunities to explore and teach both the physical and computational aspects of chemical instrumentation.