Holographic display with a variable beam deflection
View Patent ↗A holographic display including a spatial light modulator, and including a position detection and tracking system, such that a viewer's eye positions are tracked, with variable beam deflection to the viewer's eye positions being performed using a microprism array which enables controllable deflection of optical beams.
1. A holographic display including a spatial light modulator, and including a position detection and tracking system, such that a viewer's eye positions are tracked, with variable beam deflection to the viewer's eye positions being performed using a microprism array which enables controllable deflection of optical beams, in which a phase correction is applied to compensate for phase discontinuities introduced by the prism array in order to compensate for different optical path lengths to the viewer's eye positions.
2. Holographic display of claim 1 , in which the variable beam deflection is continuously variable.
3. Holographic display of claim 1 , in which the variable beam deflection is performed using electrowetting technology.
4. Holographic display of claim 1 , in which the variable beam deflection is performed using variable voltage differences applied to different electrodes located on different sides of each of an array of electrowetting cells.
5. Holographic display of claim 1 , in which the microprism array comprises a plurality of prisms, such a prism being an electrowetting cell, each electrowetting cell having at least two electrodes each coated with a hydrophobic insulator and an interface between a transparent conducting liquid and another fluid, a contact angle of the interface being formable as a function of a voltage difference applied to at least one of the electrodes with respect to the transparent conducting liquid.
6. Holographic display of claim 1 , in which two dimensional deflection is obtained by using two microprism arrays in series.
7. Holographic display of claim 1 , further comprising a point light source or a line light source and a lens for focusing light, wherein a virtual observer window is placed at viewer's or viewers' eyes, the virtual observer window being generated at a Fourier plane of the spatial light modulator, the virtual observer window comprising a size which is not exceeding a periodicity interval of one diffraction order of the spatial light modulator (SLM).
8. Holographic display of claim 7 , in which a focussing means placed before or after the prism array assists to converge light rays into the virtual observer window.
9. Holographic display of claim 1 , in which an optical effect of lens aberration are reducible by correcting dynamically through encoding of the spatial light modulator.
10. Holographic display of claim 1 , in which prisms of the prism array are controlled independently from each other and therefore each controlled prism establishes a beam deflection depending on the control of each controlled prism.
11. Holographic display of claim 1 , further comprising a point light source or a line light source and a lens for focusing light, wherein a virtual observer window is placed at viewer's or viewers' eyes, the virtual observer window being generated at a Fourier plane of the spatial light modulator, the virtual observer window comprising a size which is not exceeding a periodicity interval of one diffraction order of the spatial light modulator, in which a focussing means placed before or after the prism array assists to converge light rays into the virtual observer window, in which prisms of the prism array are controlled independently from each other and therefore each controlled prism establishes a beam deflection depending on the control of each controlled prism and in which the prisms do not all have a same deflection angle such that light rays exiting the prism array converge somewhat at the virtual observer window.
12. Holographic display of claim 1 , in which a prism angle calculation is performed in computational circuitry on a substrate of the spatial light modulator or in which a prism angle calculation is performed in computational circuitry situated on a substrate of the prism array.
13. Holographic display of claim 1 , in which the spatial light modulator's substrate is also used as the prism array's substrate.
14. Holographic display of claim 1 , wherein the spatial light modulator is adapted to be capable of changing phase of light interacting with the spatial light modulator and in which the phase correction is performed by operation of the spatial light modulator.
15. Holographic display of claim 1 , in which a holographic image is generated in a projection-type apparatus, where the projection involves imaging the spatial light modulator onto the prism array while a reconstruction of a desired 3D scene occurs in front of the virtual observer window.
16. Holographic display of claim 1 , in which phase compensation for the prism array is provided when imaging the spatial light modulator onto the prism array.
17. Holographic display of claim 1 , in which phase compensation for the prism array is provided by an additional spatial light modulator placed near to the prism array.
18. Holographic display of claim 1 , in which the spatial light modulator is transmissive with the prism array reflective or transmissive.
19. Holographic display of claim 1 , in which the spatial light modulator is reflective with the prism array transmissive.
20. A method of generating a holographic reconstruction of a three dimensional scene, made up of multiple discrete points, using the holographic display of any previous claim, the display including a light source and an optical system to illuminate the spatial light modulator; comprising the step of:
encoding a hologram on the spatial light modulator.