Laser Difffraction - Phonograph Record
To demonstrate interference of a laser beam by a type of grating.◙
Laser (on cart) with phonograph record.
This demonstration uses an old 33 1/3 RPM vinyl disc recording to produce an interference pattern with a laser beam. Hold the record at an angle with respect to the incoming laser beam and look for the diffraction pattern on the wall or the ceiling.
Scott R. Welty, Long-Playing Diffraction Grating, TPT 19, 187, (1981).