| The purpose of this experiment is to measure the mean wavelength and separation of the Sodium 'D' doublet using a grating spectrometer and a Fabry-Perot interferometer. Initial measurements are made visually by observing changes in the circular interference patterns created by the Fabry-Perot interferometer. Measurements are then made by projecting the fringe patterns onto a photodiode. A clock drive mechanism is used to drive the Fabry-Perot, while the photodiode output is recorded by a chart recorder as fringes are scanned. |
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