Interferometer
Safety Warnings
Danger: Laser Safety
Purpose
A Michelson interferometer splits a laser beam into two paths and recombines them, producing visible interference fringes that shift as the path length changes. Students see direct evidence that light is a wave and can explore the historical context of the Michelson-Morley experiment.
Figure 1:
The interferometer in operation showing the laser source, beam splitter assembly, and movable mirror arrangement. The bright green illumination demonstrates the coherent light path through the optical system.
Figure 2:
Full apparatus view showing the precision optical rail mounting system and adjustment mechanisms. The laser requires active cooling for stable operation during extended demonstrations.
Figure 3:
Typical circular interference fringe pattern produced when the interferometer mirrors are nearly perpendicular to the incident beam. Each fringe represents a half-wavelength path difference change.
Figure 4:
Demonstration configuration for classroom viewing with the interference pattern projected onto a screen. The bright central spot and surrounding fringes are easily visible to large lecture audiences.
Figure 5:
Detail of the beam splitter and mirror assembly showing adjustment mechanisms for alignment. Fine adjustment screws allow precise control of mirror angles for optimizing fringe visibility.
Figure 6:
Interference pattern with measurement scale allowing quantitative analysis of fringe spacing. Students can calculate the wavelength of light from the measured fringe dimensions and known path length changes.
Demo Apparatus
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