Hologram heterodyne scanners

Several techniques are proposed in this paper which use a scanning coherent light beam to produce an electrical signal which corresponds to a scanned hologram. The hologram itself is not formed at the transmitting end of the system as a physical entity, rather the modulated electrical carrier frequency corresponding to the spatial carrier frequency of the hologram is generated by heterodyning. An advantage of the hologram heterodyne scanner is that it reduces the spatial resolution required of the camera tube in a holographic television system by at least a factor of four.