Production of three-dimensional images using selectrograms

The property of a selectogram for recording and reconstructing three-dimensional images of objects with extended reference and reconstructing sources of light is analyzed. It is shown that each point of a reconstructing source reconstructs the object image independently of other points. This circumstance allows one to use, at the reconstruction stage, a light source whose spatial distribution of amplitudes and phases bears no resemblance to that of the reference source used for the selectogram recording. It is indicated that the only connection between the processes of hologram recording and reconstruction is the necessity to illuminate the selectogram at the reconstruction stage through the region previously occupied by the reference source as through an original window. The conclusion is drawn that freedom in choosing the reconstructing source structure opens up the possibility to record a selectogram using the object wave as a reference one and then to reconstruct the selectogram with a uniformly illuminated diffuser. The scheme of the selectogram recording is considered in which the reference wave is formed from the object wave by a diffraction grating. In this case, the grating can be positioned in immediate proximity to the photographic plate that substantially decreases the requirements specified to the degree of coherence of light used at the stage of hologram recording. The efficiency of the scheme proposed is verified by preliminary experiments. 6 refs., 3 figs