Resolving Power in Diffraction Microscopy with Special Reference to X-Rays

ROGERS'S1 elementary explanation of Gabor's2 technique for microscopy treats the hologram as a generalized Fresnel zone plate. I have used this idea for deriving a resolution criterion. Two point objects separated by a distance y produce two Fresnel zone patterns at the hologram with centres separated by a distance z, where z = pay/(Pa − qa), if Pa and qa are the distances from the illuminating point source of wave-length λa to the hologram film and from the film to the object, respectively. The subscript a refers to parameters of the 'analysis' while r will refer to the 'reconstruction'.