Interferometer Experiment, 2008.3.16

This is with the passive q-switch, quarter wave plates on each end of the rod (so the beam is circularly polarized within the rod), and 1/8 inch aperture on the HR and OC.

The interferometer has a 29 inch arm and a 16 inch arm (13 inch difference). The beam splitter is a piece of 1/8 inch thick glass, so there are some extra fringes from the beam overlapping with itself. (I don't want to use one of my "good" beam splitters with a pulsed laser just yet...)

To record the interference pattern, I held photo paper against the 2 by 4 where the pattern was being projected (to the left of the interferometer in the picture above). I push processed the paper, to improve the contrast, 2 minutes in dektol (normally 1 minute). I recorded each beam individually (beam block on the opposite arm), and then the two beams interfering. The serrations on the side are the shadow of the threaded rod holding the diverging lens, and the curved shadow on top is my thumb (holding the paper).

The beam quality is pretty bad, and I suspect its not quite TEM00, but there are fringes so I am happy.

Copyright 2008 Tommy Johnson