8. Conclusion

Light is therefore an extremely powerful tool for controlling shapes and displacements. Its very high propagation speed and the sensitivity of the eye or of modern photoelectric detectors make it an absolutely non-destructive tool for studying even the most fragile surfaces. Despite this high speed, the high frequencies of light radiation offer sub-micrometer wavelengths for excellent spatial resolution. Spatial resolution, on the order of a wavelength in lateral imaging, can be improved by 100 to 1,000 times thanks to interferometry, which enables interpolation within a fringe.

However, the performance of interferometry will always be limited by that of the reference beam. In a Fizeau, Twyman-Green or Michelson interferometer, the optical quality of the reference mirror will be the limiting factor. The stability of the reference arm can be a limiting factor when...