To do this experiment, we used the Ealing Electro-Optics Unviversal Interferometer (pictured below). You can see that mirror 1 (as labeled in the diagram below) is moved by a motor which drives a gear that drives the mirror by means of a lever arm. The output light comes out where the square of white paper is on the lower portion of the picture.
Remember the previously shown diagram. This shows more clearly the path which the incident will take.
In this picture, you can see our setup with the Sodium light source.
The output from the interferometer is incident upon the photo multiplier tube (the potential difference across the photo multiplier is supplied by a voltage source of about 300 V) where incident photons are converted (via. the photo-electric effect) to electrons. The tube increases the signal which is input into the voltmeter. The voltmeter amplifies the signal which is output to a computer for data collection. The same base setup was used with HeNe laser, except that the HeNe laser was the light source. This setup is pictured below:
click picture to see
enlarged version...
The long black tube is the Helium-Neon laser. All of the other components in the picture remain the same as the one above. The milky glass slate is used in order to have the light come from one common point. It also made it easier to switch light sources as no adjustments were necessary to reobtain the fringes.
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