Analysis on viewing angle of holographic image reconstructed from a digital Fourier hologram in a holographic display

We analyze the viewing angle of holographic image reconstructed from the digital Fourier hologram with an enhanced numerical aperture (NA). The viewing angle of reconstructed image depends on the NA of digital hologram that is determined by a focal length of Fourier lens and hologram size. The enhanced-NA digital hologram reconstructs the image with an angle larger than a diffraction angle of hologram pixel. We also characterize the aliasing effect of digital Fourier hologram, and find that the alias-free region exists even at a high numerical aperture. Numerical simulation and optical experiments are conducted to verify this interpretation of viewing angle of holographic images.