Automated High Resolution Spectroscopy
Scott D. Laurin '06

Scott with the Twyman-Green Interferometer (and the ever present can of WD-40)

Abstract:

   We are developing a prototype for high-resolution spectroscopy that could be used in advanced physics laboratory courses, e.g. the Zeeman effect. We adapted an existing Michelson Interferometer to be driven by a precision stepping motor which is controlled by a computer. The interferometer was originally intended to be adjusted manually, but this proved to be much too coarse of an adjustment to be useful for most applications. The motor and data acquisition are controlled by the same computer program; as the motor is stepped, the data is recorded by the computer. The interferometer was calibrated using the Helium-Neon laser wavelength of 632.8 nanometers. As a test we attempted to resolve the closely spaced sodium vapor yellow lines (0.6 nm) and the mercury vapor yellow lines (2 nm). Narrowly spaced wavelengths produce a “beat” phenomenon in the interference pattern which can best be interpreted by using Fourier analysis. We report our results on wavelength measurements of sodium and mercury and draw our conclusions about the capabilities and practicality of the prototype for high-resolution spectroscopy.

   For more information, contact Dr. Brian Watson:

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