M3-01: MICHELSON INTERFEROMETER - LASER LIGHT

PURPOSE: To show laser light fringes using a Michelson interferometer.

DESCRIPTION: This experiment uses the laser and white light combination Michelson interferometer setup, which remains set up and aligned and only needs the light source to be installed. The system is pre-aligned according to procedures in the file. The laser light is expanded by a 2 cm focal length convex lens and reflected into the interferometer by a front surface plane mirror, sitting beside the laser in the photograph. Either circular or straight line fringes can be displayed by adjusting the tilting mirror (left front on the interferometer). The light exiting the interferometer is focused onto a distant screen, providing a field about one foot in diameter, clearly visible over the entire lecture hall.

The photographs below show the pattern with a long path length difference between the mirrors (left), with one mirror tilted (center), and with the two optical path lengths equal (right).

Short videos are available showing the movable mirror moving from the outer postition inward (in QuickTime, Real Media, Windows Media and MPEG,) moving from the inner position outward (in QuickTime, Real Media, Windows Media and MPEG,) and line fringes seen near the equal path-length position (in QuickTime, Real Media, Windows Media and MPEG.)

SUGGESTIONS:

REFERENCES: (PIRA 6D40.10) See Demonstration Reference File for alignment procedure using laser as well as lots of articles dealing with the Michelson interferometer.

EQUIPMENT: Michelson interferometer setup, pre-set as photographed.

SETUP TIME: 5 min.

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