Recent advances in computer generated hologram applications

Computer generated holography (CGH) was invented by A.W. Lohmann and his colleagues in 1966 to create wavefronts that need to be defined only mathematically. Their design of computer generated holograms is based on detour phase, which refers to the phase shift introduced to the light diffracted from an aperture in a sample cell in a hologram. The actual CGH consists of many apertures of various sizes at positions shifted by various amounts from a 2-D array of regularly spaced sample points. At a certain diffraction angle, the position of the aperture relative to the center of the sample cell determines the phase, the size of the aperture determines the amplitude of the diffracted light. Hence, when a wavefront passes through a CGH, it will be modulated both in amplitude and phase differently by different sampled apertures.

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