Abstract
Moiré contouring method by parallel light is realized using holography. In Fourier-transform holography, the object placed at the focus of a collimating lens is equivalent to the one placed at infinity. Regular fringes are projected onto the object by tilting the illuminating parallel light slightly between the exposures of double exposure holography. These fringes are deformed by the relief of the object. Imaginary hyperboloids of interference fringes are formed by fine lateral displacement between the two exposures. As the plate is located at the focus of the lens, it is considered that the hyperboloids can be approximated by a set of parallel planes after passing through the lens. These parallel fringes are observed at infinity as a regular grid. The combination of this regular grid with the deformed fringes produces contouring fringes on the object at infinity.