Holography with concave mirrors

Holography can project 3D floating images. However, it is quite difficult to generate holograms, which have 3D information of an object, in real time because the amount of computation required for hologram generation is huge. We can reduce the computational amount by locating an object near hologram because the amount of computation required for hologram is proportional to the square of distance between the object and the hologram. However, in this case, we cannot project 3D floating images because holographic images are reconstructed near the hologram. Then, we developed a simple holographic aerial projection system which utilizes two concave mirrors to project floating images. The right figure shows an example of 3D floating motion pictures projected by the developed system.