Fourier Spectroscopy with the Michelson Interferometer
The HeNe Laser was used in this experiment because of its known wavelength. Using the Fourier transform for this light source, I was able to calibrate the other graphs accordingly. It was also hoped that the HeNe laser would provide for a very narrow peak showing its monochromatic nature. The following graphs show the results of the HeNe laser transform.
While these graphs do show a single frequency existent in the
laser light, the width of the spectrum is greater than had been
hoped for. This is most likely due to the small amount of time
(180 seconds) during which data was taken. More data would most
likely narrow this peak around 632.8 nm.
The sodium lamp emits light in the visible spectrum mostly in the yellow region. The sodium spectrum shows many lines in this range. Also note the waving of the sodium inteferogram. The sodium lamp emitted a very inconsistent intensity of light.
The sodium spectrum does show a strong wavelength presence near
The cadmium lamp emits visible light in the green-blue range. It also has a strong presence of in the ultraviolet range which the data was able to pick out.
The white light filter used passes a band of wavelengths centered around 632.8 nm with a FWHM of 10 nm. The interferogram shows that the interference pattern exists only in one small range of path-length differences.
Similar to the filtered white light, the white light inteferogram shows an even narrower interference pattern.