Off-axis digital holography based on the Sagnac interferometer

Abstract

Abstract In this paper an off-axis holography is put forward based on the Sagnac interferometer. The holograms of alumina-dust aerosol particles, an United States Air Force 1951 resolution plate and paramecium were recorded in the experiment. The diffraction integral of a plane hole derived from quantum theory is illustrated by the variation of the thickness of interference fringes. We use an angular spectrum diffraction algorithm to reconstruct the recorded hologram, and the reconstructed image with high resolution is obtained after eliminating the zero-order image and conjugate image. Examples involving alumina-dust aerosols demonstrate the technique’s in situ imaging capability for complex-shaped particles over a size range of roughly 10–50 µm micrometers. The system’s feasibility is analyzed and thus confirmed.