Abstract: A holographic method of the type implementing a conoscopic system including a birefrigent crystal inserted between two polarizers and a photosensitive element, wherein the method includes a step consisting in inserting one-dimensional optical means on the path of the light rays such that the conoscopic system only collects light that is parallel or quasi-parallel to a plane including the axis of the conoscopic system. The invention also provides apparatus for implementing the method.

Abstract: A particle size analyzer device for granular and cellular substances composed of particles having sizes lying in a given dimensional range comprises a coherent light source for illuminating a sample of the substance and means for forming the two variable Fourier transform of the sample, i.e. its bidimensional diffraction spectrum. A monodimensional portion of the bidimensional spectrum is isolated along a radius thereof determining an amplitude function versus the radial distance from the center of the spectrum. This amplitude function is processed by successively (i) computing its Hankel transform, (ii) and deriving the second derivative of the Hankel transform. This second derivative is a convolution product of the distribution function of the particle sizes by another function. The distribution function is extracted from said convolution product.