The Instrument

This summer research project greatly expanded upon the work done previously by Brett Berger in his Senior Thesis (see work here). In Berger’s device, however, the current increased exponentially with the input voltage, making the laser quite unstable. This summer’s group came up with an op-amp circuit design that would be controlled by a potentiometer and provided a linear relationship between the current and voltage. After weeks of testing, the team found that though the current was stable, the temperature and power output of the laser greatly fluctuated with time, also making the laser unstable. This also posed a potential threat to the laser and/or sample, as they may overheat and be damaged. In the future, the lab hopes to design a temperature-control circuit that will not greatly cut down on the power output of the laser. Below is a diagram of the circuit implemented:



In order to make the instrument adaptable, the team also made changes to the instrument itself. A new stage was designed to hold a cuvette for liquid samples, a slide for solid samples, and a power meter to measure the laser power output. The team also stationed the spectrometer inside a box with the inside painted black in order to minimize background noise in the spectra and to absorb any laser light that may bounce and reflect. Below is a photograph of the adapted instrument: