Patent ID: 8355190

Claim:
Method for reducing speckle in a three-dimensional holographic reconstruction created in a holographic display device, comprising: encoding a hologram of a 3D scene on a controllable light modulator and illuminating said hologram with sufficiently coherent light, using an optical reconstruction system, transforming the light which is spatially modulated in the light modulator into the rear focal plane, where an observer window is formed in the rear focal plane, and reconstructing the 3D scene in a reconstruction space, and controlling the illumination of said hologram with a control means, wherein: the control means controls the illumination of the light modulator such that multiple modulated complex-valued wave fronts of the same 3D scene with slightly different wavelengths exit the light modulator; the optical reconstruction system transforms said wave fronts into the rear focal plane where they are superimposed, and generates from each complex-valued wave front a reconstruction of the same 3D scene in the reconstruction space; the slightly different wavelengths are in a wavelength range within several nanometres of each other; and the individual reconstructions are slightly modified reconstructions of the same 3D scene with modified speckle patterns in the reconstruction space, said reconstructions being averaged from the eye position as a single reduced-speckle reconstruction of the 3D scene.