6D40.10 • Interferometers: Michelson Interferometer

Photo Shows the Demonstration Used at the University of Texas at Austin.

Instructions / Notes:

• Michelson interferometer shown above is for a large classroom.
• This version of a Michelson interferometer utilizes:
  • A 5 mW laser
  • A lens between the laser and beam spitter slightly expands the laser beams.
  • A double-prism beam splitter
  • Two front surfaced mirrors
  • Only one mirror has an X versus Y adjustment
  • The second mirror has an adjustment towards or away from the beam spltter
• Room lights must be dimmed for students to see the projected interference fringes, shown below.
  • At the bottom-left of one mirror is a horizontal adjusting screw to move one of the reflected laser beams to the left or right.
  • Only a slight tweak on the adjustment knob significantly the moves the reflected pattern either into or out of alignment.
  • A slight tweak is about a 5 degree turn of the adjustment knob.

Photo shows the interference pattern with both reflected laser beams overlapped. (Notice that the room lights have been dimmed.)

• Demo staff: Please set up the demo cart so it is about 6 feet from the wall or one of the white prep-room doors, so the class can see the merged beams.
• Small adjustments in the mirrors or noise in the room will greatly alter the interference fringes.

Last updated on August 30, 2017