Image Luminance and Ray Tracing in Holography

Abstract

Image formation in holography is treated by means of the Fresnel-Kirchhoff diffraction formula. The luminance of an image formed by paraxial rays is calculated, and its dependence on the resolution loss in the photographic film is evaluated. It is estimated that at most 1/16 of the light striking the hologram goes into each image. When a hologram is viewed, a glow is observed to surround the source of coherent light. It can be attributed to two causes, the granularity of the photographic emulsion and random interference between waves reflected from pairs of points on the object when the hologram is recorded. The luminance of each of the components of the glow is calculated. Ray-tracing equations are presented, and formulas are derived for locating the foci of the astigmatic pencils of rays emitted by the hologram when coherent light is incident.