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of other outdated instruments, providing opportunities to explore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.

学术界日益认可创客运动（Maker movement）所带来的发展机遇，自制实验仪器的创作数量显著增长，其中光谱学领域的相关成果尤为突出。此类仪器正被用于提升课堂教学与教育项目的参与度与互动性。
多数专为教育场景设计的自制仪器，均采用简化的3D打印构件与/或适配改装的材料，例如将光盘用作衍射光栅（diffraction grating）。
本文提出一种全新解决方案：对一台因通信协议过时而退役的老式液相色谱仪的光学系统进行回收再利用。
完整保留该色谱仪的光学系统，并将原有的光电二极管阵列（Photodiode Array, PDA）替换为可通过Arduino便捷控制的新型光电二极管阵列，同时为本项目开发了专用用户界面。
本文将展示一张用于说明吸光度计算相关界面操作的流程图，随后讨论传感器的安装位置对所采集光谱的波形可能产生的影响。
本研究获取的原始数据，还可用于讲授暗电流（dark current）、基线校正、仪器校准与吸光度等相关概念。
本文展示了利用该自制仪器获取的多种物质的可见光谱，并将其与商用台式分光光度计的测量结果进行对比。
本文所述方案可为其他老旧实验仪器的回收再利用提供思路，同时为讲授化学仪器分析的物理原理与计算方法提供教学实践场景。