Holographic imaging and interferometry with non-bragg diffraction orders in lithium niobate and photo-thermoplastic materials [Articol]

Abstract

We investigated recording of holographic volume and surface-relief gratings in photorefractive crystal and in a photo-thermoplastic (PTP) holographic camera. Holographic recording with an image-bearing signal beam leads to the appearance of two Bragg and two or more non-Bragg diffracted beams that shows the transformed images in each beam (rotation and angular amplification of images). Using this real-time mode of interferometry, the hologram is retrieved with a deformed object beam, resulting in the appearance of fringes with a proper phase shift in each of four diffracted beams. Retrieval with a time-modulated single-pixel object beam lead of time- modulated response in all diffraction orders. This one-shot (one-exposure) phase-shifting interferometry results in clarifying the object wave-front information (as an example, from the surface deformation) and solving the sign ambiguity problem. This procedure demonstrates that high-resolution holographic imaging of the PTP holographic camera static deformations in the order of ~0.1mm can be revealed on the diffusion reflection surface. In addition, it was demonstrated, that using the PTP materials could achieve holographic recording and imaging through phase aberration, with the image appearing in the non-Bragg diffraction order.