Reflection holograms with a high diffraction efficiency

An investigation was made of the exposure dependences of the parameters of reflection holograms of a mirror recorded in opposite beams of He–Ne laser radition (λ₀ = 632.8 nm) on Agfa Gevaert 8E75 photographic plates. The holograms were treated in Metinol–U and D–19 developers, fixed, and bleached in a solution of K₃Fe(CN)₆ and KBr. The diffraction efficiency of the bleached holograms was 20–25% when the width of the diffracted radiation spectrum was about 20.0 nm (at the 0.5 level of the maximum amplitude). The wavelength of the diffracted radiation maximum shifted by 5–8% in the direction of shorter wavelengths for exposures corresponding to the efficiency maximum. When the shrinking of the emulsion was eliminated, the efficiency increased considerably (to 40%). Holograms with a high brightness of the reconstructed image and a satisfactory noise level were obtained after exposures of ~0.2 mJ/cm².