Fast diffraction calculation of cylindrical computer generated hologram based on outside-in propagation model

Cylindrical computer-generated hologram is a promising approach to realize a display with 360°field of view. However, conventional cylindrical hologram employs an inside-out propagation model and suffers from two main drawbacks: limited object size and lack of effective reconstructed method. Previously, we proposed to fix these problems using an outside-in propagation model with reversed propagation direction of the inside-out model. We also derived corresponding diffraction calculation formula for the outside-in propagation model. In this work, we investigate a non-constant obliquity factor in the outside-in propagation model, and show that it is the projection of the unit complex amplitude in the propagation direction onto the outer normal of the observation point. We then propose to apply fast Fourier transform to accelerate the convolution operation needed for diffraction calculation. We conducted experiments on inverse diffraction and reconstruction of the cylindrical objects. Very encouraging results demonstrate the validity of this proposed approach.