To realize an interactive holographic 3D display system, the system falls into three processes: the first is the generation of original 3D object data; the second is the computation of hologram patterns; the third is the modulation of electro-holographic display devices. These must be executed fast and continuously for 3D display. In these processes, the fast computation of holograms is the most important process. We investigate this process using a fast computation algorithm with a fast computing system, and fabricated a prototype of the interactive holographic 3D display system. We discuss the fast computation algorithm using a transform from frequency domain to spatial domain compared with the traditional computation method of the Fresnel hologram, reduction of calculation time using our fast computing system.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.