Group refractive index measurement by Michelson interferometer

A Michelson interferometer illuminated by a polychromatic light source was used to measure the time of flight of a light pulse (or intensity substructure) through a sample of optical material. In this way the group index of optical materials (fused silica and Schott glass F3) was measured with an accuracy of 10 ^-4. The method can be also applied for measurement of the dispersive properties of optical fibers.