Real-time and two-reference-beam hologram interferometry: effects of emulsion shrinkage

When transmission holograms are recorded on photographic materials, any change in the thickness of the photographic emulsion due to processing can produce a change in the spacing of the carrier fringes. We show that the resulting change in the angle at which the image is reconstructed when the hologram is illuminated with the original reference beam can give rise to significant errors in real-time and two-reference-beam hologram interferometry.