Principles of digital holographic interferometry

Fresnel or Fraunhofer holograms can be recorded by CCD arrays as long as the sampling theorem is fulfilled. The numerical reconstruction of the wavefields is performed either by the discrete finite Fresnel transform or by solving: the diffraction integral using the convolution theorem. The availability of the digitally evaluated complex wavefield instead of only the intensity field in optical reconstruction allows the subtraction of the phase distributions belonging to two states of the object to yield the sign-correct interference phase distribution with high accuracy. A numerical compensation for excess motion as well as effective filtering of the interference phase modulo 2 pi are feasible.