The Bending of Interference Fringes inside a Hologram

The bending of interference fringes inside a hologram due to a prestress in the photographic emulsion is investigated. The influence of the bending on the diffraction efficiency and the angular sensitivity is explained qualitatively in terms of the Fresnel-Kirchhoff diffraction theory. The quantitative analysis is carried out using the coupled wave theory with the attenuated grating model. Experimental results obtained using a Kodak 649 F plate are compared with the theory. The bending is found to be zero at the emulsion surface and its shape was represented approximately by a quadratic curve in the direction of the emulsion thickness.