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Interferometer FringesLaser Interferometry

Price: Item discontinued, no longer for sale ....

Laser Interferometry is a mainstay of modern physics, belonging in every physics teaching lab.  With this experiment, students assemble and align the interferometer themselves, learning about modern optical components, mounting hardware, and alignment procedures.  They observe the interferometer fringes first hand (e.g. the image at right),  plus they send the beam to a photodetector, modulate the position of one mirror using a piezoelectric transducer, and then observe the interferometer fringes on the oscilloscope, connecting the visible fringes to an electronic signal.

The interferometer signal is then fed back to the mirror to lock the interferometer at its most sensitive point.  From there students can modulate the mirror position at high frequencies (while maintaining the lock at low frequencies), thereby observing the modulated signal on the oscilloscope.  By using a series of signal averaging techniques (including a built-in basic lock-in amplifier), students can observe picometer displacements with this instrument -- 1/100th of an atom!  This is over a 10-cm-long arm length, which is like measuring the distance from New York to Los Angeles with a sensitivity of the width of a human hair!

The Laser Interferometer package also includes a mirror mounted to a mechanical oscillator, essentially one arm of a tuning fork.  Students can use their interferometer to observe nanometer motions of this oscillator, thus characterizing its properties.  In this way students see how laser interferometry can be used as an effective tool for making precision displacement measurements.


Written Documentation - Laser Interferometry
Click on the links below to download .pdf files describing the hardware, the experiments, and the physics of ion trapping.

1. A Description of the Laser Interferometer Instrument
        A paper describing the Laser Interferometer as a teaching tool (submitted for publication in the American Journal of Physics).

2. Sample student handout

Video Documentation - Laser Interferometry

Click on the links below to YouTube videos of ion traps and trapping experiments.

Coming Soon ....

Photo Gallery - Laser Interferometry

More Images coming soon ....