Fizeau interferometric device for measuring wavefronts.

Gary E. Sommargren of Madison, CT.

This is Figure 1 of a US Patent granted to Mr. Sommargren (US 4,594,003) in 1986 by the US Patent & Trademark office.

A Fizeau interferometer is similar to a Fabry-Perot interferometer in that they both consist of two reflecting surfaces. In a Fizeau interferometer, however, the second surface is usually totally reflecting. An angled beam splitter captures the reference and measurement beams.

Fizeau interferometers are often used in fiber optic sensors for measuring pressure, temperature, strain, etc. They are ideal as robust measuring instruments that can be used in hostile environments. For example, a fiber optic can be placed near the surface of a boiler. The fiber is held in place by a resin, which expands and contracts as a function of temperature. A small gap is maintained between the fiber and the surface. The cleaved and polished fiber end makes up the first surface of the interferometer, and the boiler surface makes up the second. As the temperature changes, the gap distance changes, altering the optical path difference. A detector can then plot the change in light and accurately indicate the temperature of the boiler.

See also

* Hippolyte Fizeau

* List of types of interferometers