Along with optical components and detectors, the kit includes all of the light sources needed for the wide variety of possible investigations included in the manual. In addition to a He-Ne and a variable-temperature red diode laser, a bi-colored LED and a halogen lamp are included for the study of white-light interferometry. The electronic controller is used not only to count fringes but also to support the optical detectors and the power supplies needed for all of the various light sources.
The photograph above shows a Michelson interferometer. You can see the He-Ne laser and the two steering mirrors that deliver the beam to the interferometer proper. Both the beamsplitters and the end-mirror mounts are proprietary designs, optimized for stability and simplicity of alignment. The electronic detector complements the visual detection of the fringes.
The prototypes for the proprietary high stability flexure mirror mounts were designed by Science Research Laboratory, Inc. (SRL) of Somerville, MA as part of an educational interferometer developed under an NSF SBIR. With large mirror surfaces and flexure tilts that allow only one degree of freedom, these mounts make alignment not only impressively stable but also far more straightforward.
At TeachSpin, the development team of Drs. George Herold, David Van Baak and Jonathan Reichert expanded the initial Sagnac interferometer system into a wide ranging, open-ended "kit" which offers students a large "intellectual phase space" in which to learn experimental physics. Looking for a way to observe minute changes, Van Baak designed a proprietary high stability flexure translation stage which allows a full millimeter of motion with no loss of fringe contrast. (We expect that this translation stage may well find other uses!)
The hardest part of building this kit was getting the TeachSpin team to stop adding new experiments and let faculty and students have a turn taking advantage of the impressive capabilities of this student-friendly system.
Please read about it in the Modern Interferometry Brochure (PDF 3.5 MB).