Major ideas
1. In the Michelson interferometer, a beam splitter divides a beam of light into two paths that are reflected from end mirrors and then recombined at a detector. The resulting combination of wavefronts yields patterns of constructive and destructive interference that are useful in a variety of measurement tasks, including highly precise measurement of length.
2. The observation of constructive and destructive interference depends both on the alignment of the super-imposed wavefronts from the two paths and on the coherence properties of the light source. (Note: the quantitative observation of coherence properties will be developed in future versions of this experiment. For now it suffices to have some understanding of why this idea is important. There are discussions in the manufacturer's manual and in the references.)
Major equipment
1.) Beam splitting mirrors of two types: dielectric film and metal film.
2.) A precision mechanism for motorized translation of one mirror with micrometer readout.
Other key equipment include optical mounts including mirror holders with adjustable tilts, an optical breadboard, Helium-Neon and diode lasers, a photodiode detector, an amplifier/counting circuit housed in the system control box, and a digital sampling oscilloscope for viewing and capturing the photodetector output.
Data analysis
1.) Student's choice for interpreting photodetector output as a function of mirror translation.
2.) Student's choice for using fringe count data.
Here are three questions that give you insight into important quantitative features of the experiment.
IMPORTANT: you must complete the laser safety training before proceeding with this experiment. See Kris Bunker.
See the equipment manufacturer's guide linked here as well as a hard copy to be found in the lab room. (Please do NOT remove the hard copy from the lab.) Concentrate on the procedures for aligning the interferometer and for using the fine-translation mechanism and fringe counter to measure the wavelength of the laser light.
You will also find it useful to consult the document prepared by Dr. Sahami in the attachments below.
Hariharan, P. (1992), Basics of Interferometry (Academic).
Steel, W. H. (1986), Interferometry, 2nd ed. (Cambridge Univ. Press).
See also:
Candler, C. (1951), Modern Interferometers (Hilger and Watts).
Dyson, J. (1970), Interferometry As a Measuring Tool (Machinery Publishing Co.).
Francon, M. (1966), Optical Interferometry (Academic).
Tolansky, S. (1973), An Introduction to Interferometry, 2nd ed. (Halstead/Wiley).