Method for computing the code for the reconstruction of three-dimensional scenes which include objects which partly absorb light or sound. The method can be implemented in a computing unit. In order to reconstruct a three-dimensional scene as realistic as possible, the diffraction patterns are computed separately at their point of origin considering the instances of absorption in the scene. The method can be used for the representation of three-dimensional scenes in a holographic display or volumetric display. Further, it can be carried out to achieve a reconstruction of sound fields in an array of sound sources.

A totagram is produced by an iterative spectral phase recovery process resulting in complete information recovery using special masks and using a reference beam. Using these special masking systems reduce computation time, number of masks, and number of iterations. Adding a reference wave to the iterative process provides better phase recovery systems and aid in the preventing of phase wrapping. The reference wave is added on-axis to provide a well-controlled amplitude. The reference wave is added after the physical or digital transformation system and subtracted before recording the initial amplitude. An additional camera at the input plane records the amplitudes of the original input wave which are used during the iterative process.

An illumination system is arranged to output a light beam for illuminating a scene. The system comprises a spatial light modulator arranged to receive incident light, and to output light comprising a first component and a second component. The first component comprises incident light that is output without modulation by the spatial light modulator. The second component comprises incident light that is spatially-modulated according to a hologram and output by the spatial light modulator. A control device is operable to control the proportion of light output by the spatial light modulator that corresponds to the second component.

A three-dimensional holographic display device includes a light emitting diode (LED) array including a plurality of light sources controlled to sequentially output light according to a preset pattern, a lens configured to refract light incident from the LED array, a spatial light modulator (SLM) configured to modulate light incident from the lens, and a processor configured to generate a plurality of holographic signals each comprising depth information adjusted according to an arrangement location of each of the plurality of light sources, and for each of the plurality of light sources, control the SLM to modulate the light based on a holographic signal corresponding to the light source.

A method of forming two distinct images in a substrate includes controlling a high-energy beam to form a profile ridge in the substrate, and thereafter defining a first set of features on a first side of the profile ridge, the first set of features representing a first distinct image when the substrate is perceived by an observer from a first angle, as well as defining a second set of features on a second side of the profile ridge, the second set of features representing a second distinct image when the substrate is perceived by an observer from a second angle. Both the first set of features and the second set of features are positioned in a common vertical substrate space of the substrate.