Television Transmission of Holograms Using a Narrow-Band Video Signal

Enloe, Murphy, and Rubinstein transmitted off-axis or carrier-frequency holograms by means of television. 1 Although they were successful, they were severely restricted by the limited resolution of the television camera tube. This fundamental difficulty has its roots in the fact that a carrier-frequency hologram has spatial frequencies at least four times higher than the highest spatial frequency contained in the subject. (This fact is elaborated on in Ref. 2.) Burckhardt and Doherty 3 were later able to produce carrier-frequency holograms using an on-axis reference beam. Figure 1 shows the arrangement they used. A Mach-Zehnder interferometer was used to align the subject and reference beams, and a means was provided for shifting the phase of the reference beam. A transmission grating was placed in front of the photographic plate used to record the hologram. A series of four exposures was made on a single photographic plate. Between exposures, the transmission grating was translated laterally by one-fourth of its spatial period, and the reference beam was shifted in phase by 90°; the resulting synthesis at the photographic plate was a carrier-frequency hologram. 879