Digitally sampled in-line holograms may be linearly filtered to reconstruct a representation of the original object distribution, thereby decoding the information contained in the hologram. The decoding process is performed by digital computation rather than optically. Substitution of digital for optical decoding has several advantages, including selective suppression of the twin-image artifact, elimination of the far-field requirement, and automation of the data reduction and analysis process. The proposed filter is a truncated series expansion of the inverse of that operator that maps object opacity function to hologram intensity. The first term of the expansion is shown to be equivalent to conventional (optical) reconstruction, with successive terms increasingly sup-pressing the twin image. The algorithm is computationally efficient, requiring only a single fast Fourier transform pair.

Digital decoding of in-line holograms

A simple noniterative algorithm for retrieval of the unknown phase shifts in phase-shifting holography is proposed. In this algorithm, the phase shift value between two phase-shifting holograms can be calculated through a simple analytical formula that is derived according to the fact that there exist some points whose intensity difference between two phase-shifting holograms is equal to zero. Both the simulated and experimental results demonstrated the feasibility of this so-called zero difference algorithm over a wide range of phase shifts.

Zero difference algorithm for phase shift extraction in blind phase-shifting holography.

A phase calculation method using spatial derivatives of quadrature phase-shifted fringes is presented and its applications to interferometry and digital holography are also described.

Phase Calculation Method Using Spatial derivatives of Quadrature Fringes and Its Application to Digital Holography

A calculation method for a quadrature phase-shifting interferometer is presented, and its applications to specular and speckle interferometers and digital holography are described. Two sets of quadrature phase-shifted interferograms are acquired, and the calculation method proposed gives the phase distribution of the interferograms. The principle of the calculation method with error analysis and experimental results for specular and speckle interferometers and digital holography are also given.

Calculation method for a quadrature phase-shifting interferometer and its applications

A new calculation method for a quadrature phase-shifting interferometer is presented. The principle of the calculation method with computer simulations and its application to digital holography with experimental results are also given.

Shinya Sawada

Papers

Calculation method for a quadrature phase-shifting interferometer and its applications

New Calculation Method for Quadrature Phase-shifting Interferometer and Its Application to Digital Holography