Slightly off-axis flipping digital holography using a reflective grating

A slightly off-axis digital holography is proposed using the flipping interferometry with a reflective grating to obtain the quantitative phase distribution. The setup is established based on a modified 4f optical system using an improved flipping module with a reflective grating and a retro-reflector made of a two-mirror construction. The input plane of the system is divided into two windows: one for object beam and the other for reference beam. Employing the flipping module, the interference patterns can be obtained by flipping the images of the object and reference beams. By translating the +1 diffraction order of the reflective grating, two carrier holograms with a phase shift between them can be obtained in two exposures. The reconstructed quantitative phase distribution of a specimen can be acquired with a simple slightly off-axis retrieval method aided by specimen-free holograms. Many measurements on both thick and thin phase specimens are performed to prove the validity of our method.