XXIX ENFMC - Annals of Optics 2006 3D shadowgram projection using a simple diffractive screen José J. Lunazzi, Noemí I. Rivera Rodríguez. Universidade Estadual de Campinas - Instituto de Física lunazzi@ifi.unicamp.br , nrivera@ifi.unicamp.br Abstract We present a new system where a 3D object is projected on a diffractive screen, which is just a simple diffractive holographic lens. The object is illuminated with an extended filament of a white light lamp and no additional element is necessary. The system forms three-dimensional (3D) images with normal depth (orthoscopic) of the shadow type. The continuous parallax, perfect sharpness and additional characteristics of the image depend on the width and extension of the luminous filament and the properties of the diffractive lens. Introduction Lunazzi [1] developed ways for obtaining 2D and 3D images with white light using diffractive elements usually through projection by a diffractive lens. The only method we know other authors developed is for 2D images in a system by Hyde [2] named EYELIGHT: Very large aperture diffractive telescopes. On the other hand, were obtained 3D images that are perfectly symmetric and depth inverted (pseudoscopic) from a double diffraction system using gratings diffraction intermediated by a slit [3-5], in this same system we observed the image with normal depth (orthoscopic images) [6]. The pseudoscopic image appears in the front of the screen as a ghost image and other appears back of screen forming a virtual image. These images are observed in a first diffraction order and they show the following characteristic as horizontal parallax, horizontal magnification and vertical astigmatism. 3D images also can be obtained using two bi-dimensionally defined diffractive elements and an intermediary pinhole [7-9], and the characteristics of the system are: equal horizontal and vertical magnification, possibility of projection because it does not present astigmatism. There is a purely one-step diffractive system for projection of a 2D object illuminated with an extended filament lamp of white light on a diffractive screen to form a 2D image of a transparency [10] that we used to explain a new system of 3D images consisting in the projection of a 3D object on a diffractive screen illuminated with an extended filament of a white light lamp, this image shows characteristics as normal depth, continuous parallax and perfect sharpness. Experimental Setup The process for obtaining 3D images using only diffraction is described in the Figure 1. f represent the white light source filament from which each point (for example point, f 1 ) is considered to send white light rays in all directions. Point f 2 represent a point of the filament, f 2 emanates some rays that arrive the object O1, making a shadow whose contour rays impinge the DS (diffractive screen). The prolongation of these diffracted rays of blue wavelength and red wavelength converges in the observer pupil. The observer is located in the same side that the diffracted rays (blue and red wavelength), in this position may observe the images i1 with perfect clarity.