Improvement of Fresnel Computer-Generated Holograms.

Computing Fresnel holograms usually requires the use of the analytic form of a Fourier transformed quadratic surface, because the Fresnel approximation leads to a convolution of the object plane and a quadratic surface. We present here a new method in which we do not approximate spherical wavelets: we get rid of the so-called inclination factor but we do not expand in binomial series the distance between the object plane and the hologram plane as done in Fresnel approximation. We demonstrate the analytic form of the Fourier transformed spherical wavelets and show that Fresnel approximation is no more necessary. We present experimental verifications of Fresnel holograms computed with spherical wavelets and quadratic surfaces.JRC.(ISIS)-Institute For Systems, Informatics And Safet