Digital in-line holography phase reconstruction without twin-image removal using fractional Fourier transform

Abstract In digital in-line holography, the overlap of the original image, twin image, and zero-order term makes it challenging to directly reconstruct the phase from a single in-line hologram. This study leverages the quadratic phase property of lenses and the chirp signal parameter estimation capability of Fractional Fourier Transform (FrFT). By analyzing the intensity distribution relationship along rows and columns of the in-line hologram, a background light suppression algorithm based on differential chirp signals is proposed, effectively eliminating the interference of background light on parameter estimation. This approach enables phase reconstruction and lens sag height measurement from a single in-line hologram without additional artifact removal. Simulation and experimental results validate the feasibility of the proposed algorithm.