Study of digital 3D holographic display using scattering media

Abstract

Holographic display is an ultimate type of 3D display which can precisely replicate real world scenes. The holography records the exact light field of natural scenes and plays back the realistic 3D images from the recorded field information. After the early holography experiments with analog recording media, the development of the digital 3D holographic display has been pursued with the growing needs for realistic 3D digital contents in various fields. However, the limited space-bandwidth product (SBP) of the digital wavefront modulators is a great obstacle for the practical viewing angle and image size. In the perception of real objects, diffused light scattering in all directions enables people to see the object at various viewing angles. In contrast, the hologram generated by the digital wavefront modulator is solely governed by the limited deflection angle and small size of the wavefront modulator. Therefore, deliberately generated diffused light can be possibly utilized for increasing viewing angle and image size. In this thesis, we exploit the multiple light scattering to overcome the limitation of SBP of the digital 3D holographic display. Although the multiply scattered light exhibits complex propagation behaviors, the whole process is governed by Maxwell’s equation and can be controlled in a deterministic manner. Using wavefront shaping techniques with scattering media, we develop three main subjects in this thesis. 1) projection of 3D images with wide viewing angle and image size, 2) projection of visible focus through scattering media and 3) recording of 3D hologram through scattering media with enhanced viewing angle and image size. By controlling the volume speckle generated by holographic diffusers, the image size and viewing angle of the display is enhanced three orders of magnitude compared to a deformable mirror. We also propose a new wavefront shaping technique to enhance the visibility of the 3D focus. Finally, we develop the holographic recording system using digital time-reversal mirror based on the single-channel point focusing. We hope that findings of this thesis will advance the development of realistic 3D holographic display.