Interferometry can be extremely useful for testing optical components and optical systems as
well as the metrology of many other components, such as the flatness and roughness of hard disk
drive platters, the shape of magnetic recording heads and machined parts, and the deformations
of diffuse surfaces. To make good use of interferometric data the data must be analyzed by a
computer to determine if the surface shape is correct or not and if it is not correct what has to be
done to correct it and how well the surface being evaluated will perform if it is not corrected.
Until recently a major limitation of interferometry for precision metrology was the sensitivity to