Phase-shifting digital holography and applications

摘要

In digital holography holograms are recorded by a CCD camera and image reconstruction is performed by a computer that calculates the diffraction from the hologram. In phase-shifting digital holography an in-line setup is employed in the recording to reduce the spatial frequency spectrum of the hologram, and the distribution of complex amplitude on the CCD is directly derived by means of phase-shifting of the reference beam and subsequent analysis of hologram patterns to suppress the conjugate image. It uses a simple optical setup and delivers distributions of complex amplitude including both amplitude and phase in three-dimensional space without mechanical focusing. We apply this method to microscopy and to surface contouring in which phase distributions resulting from two different angles of incidence at a diffuse object are compared to deliver surface height.