High-speed broadband slight-off digital holography based on simultaneous two-step Gouy phase shifting interferometry

It is well known that phase shift is depended on wavelength of light source by traditional optical path difference (OPD) in free space or wave plate methods. In this paper, we demonstrated a slight-off two-step Gouy phase shifting interferometry which is suitable for broadband digital holography. This technique uses Gouy phase shift to introduce π phase differences between two reference arms. A dual-channel interferometer was employed to monitor the Gouy phase-shifting between two orthogonal polarized references and snap imaging with single shot enabling potential real-time and high-speed imaging capabilities. Theoretical analysis and numerical simulation comparisons between the proposed method and some traditional phase shifting approaches for broadband digital holography were given. Accurate recovers can be obtained in ideal conditions by Gouy, OPD in free space and λ/2 wave plate methods. However, when considering of environment influence, the accuracy of the traditional methods declined rapidly, the recover errors are more than 70 and 20 times higher than our proposed method. The results also show that Gouy method can get consistent phase shift for broadband light source with little influence with wavelength.