Holographic recording with limited laser light

Various holographic recording media were compared for conditions of low signal energy densities. The peak value of diffraction efficiency divided by signal-beam exposure (Q) and of normalized contrast ratio divided by signal-beam exposure (A) for Kodak 649 F and for Agfa 8E70, 10E70, and 14C70 were determined. The quantities were optimized with respect to bleaching, hypersensitization, development, and reference beam exposure. Above some value of the reference-to-signal beam ratio these quantities were constant, while their dependence, if any, on the offset angle and signal beamwidth was not determined. The film response was considered in terms of the model T(a) = [b/(b + E(d))] (e) from which Q and A were calculated.