Digital Holographic Three-Dimensional Video Displays

Holography aims to record and regenerate volume filling light fields to reproduce ghost-like 3-D images that are optically indistinguishable from their physical 3-D originals. Digital holographic video displays are pixelated devices on which digital holograms can be written at video rates. Spatial light modulators (SLMs) are used for such purposes in practice; even though it is desirable to have SLMs that can modulate both the phase and amplitude of the incident light at each pixel, usually amplitude-only or phase-only SLMs are available. Many laboratories have reported working prototypes using different designs. Size and resolution of the SLMs are quite demanding for satisfactory 3-D reconstructions. Space-bandwidth product (SBP) seems like a good metric for quality analysis. Even though moderate SBP is satisfactory for a stationary observer with no lateral or rotational motion, the required SBP quickly increases when such motion is allowed. Multi-SLM designs, especially over curved surfaces, relieve high bandwidth requirements, and therefore, are strong candidates for futuristic holographic video displays. Holograms are quite robust to noise and quantization. It is demonstrated that either laser or light-emitting diode (LED) illumination is feasible. Current research momentum is increasing with many exciting and encouraging results.