US-12625465-B2 - Controlling spatial coherence for holography

Abstract

A holographic imaging system for capturing and displaying a high-resolution and polychromatic hologram, the holographic imaging system comprising: a plurality of monochromatic coherent light sources, configured to generate a plurality of monochromatic light input wavelengths; a polarization preserving diffuser configured to receive the plurality of monochromatic light input wavelengths at a first end of the polarization preserving diffuser, and further configured to provide a polychromatic output at a second end of the fiber; and a diffractive optical element configured to receive polychromatic light from the second end of the fiber.

Inventors

• Alexander John Michael Lesnick

Assignees

• Hot Pixel Holographics LLC

Dates

Publication Date

20260512

Application Date

20230626

Claims (20)

1. 1 . A holographic imaging system comprising: a plurality of monochromatic coherent light sources, configured to generate a plurality of monochromatic light input wavelengths; a polarization preserving diffuser configured to receive the plurality of monochromatic light input wavelengths at a first end of the polarization preserving diffuser, and further configured to provide a polychromatic output at a second end of the polarization preserving diffuser; and a diffractive optical element configured to receive polychromatic light from the second end of the polarization preserving diffuser.
2. 2 . The holographic imaging system of claim 1 , wherein the diffractive optical element is a holographic film for capturing a hologram of an object.
3. 3 . The holographic imaging system of claim 2 , wherein the holographic film is a silver halide recording medium.
4. 4 . The holographic imaging system of claim 2 , wherein the holographic film is a photopolymer recording medium.
5. 5 . The holographic imaging system of claim 1 wherein the diffractive optical element is a spatial light modulator configured to modulate the polychromatic light from the second end of the polarization preserving diffuser to generate modulated polychromatic light corresponding to a hologram of an object.
6. 6 . The holographic imaging system of claim 1 , wherein the plurality of monochromatic coherent light sources comprises a first diode laser configured to generate red light, a second diode laser configured to generate green light, and a third diode laser configured to generate blue light.
7. 7 . The holographic imaging system of claim 1 , wherein coherent light sources of the plurality of monochromatic coherent light sources each have a temporal coherence length between 1 m and 1000 m.
8. 8 . The holographic imaging system of claim 1 , wherein the polarization preserving diffuser comprises a multimode optical fiber.
9. 9 . The holographic imaging system of claim 8 , wherein the multimode optical fiber has a diameter between 3 mm and 5 mm and the diffractive optical element is configured to capture a hologram of up to 120 mm×200 mm in size.
10. 10 . The holographic imaging system of claim 8 , wherein the multimode optical fiber has a diameter greater than or equal to 5 mm and the diffractive optical element is configured to capture a hologram greater than 120 mm×200 mm in size.
11. 11 . The holographic imaging system of claim 8 , wherein a first end of the multimode optical fiber comprises a split into three fiber input ends, wherein each of the three fiber input ends is configured to receive monochromatic coherent light of a different wavelength, and wherein a second end of the multimode optical fiber comprises an unpolished output facet.
12. 12 . The holographic imaging system of claim 11 , wherein each of the three fiber input ends comprise a respective dichroic filter.
13. 13 . The holographic imaging system of claim 8 , wherein a length of the multimode optical fiber does not exceed half of a shortest coherence length of the plurality of monochromatic coherent light sources.
14. 14 . The holographic imaging system of claim 1 , wherein the polarization preserving diffuser is a holographic diffuser.
15. 15 . The holographic imaging system of claim 1 , wherein the diffractive optical element and the polychromatic output are each configured to capture a hologram of an object having a speckle size of less than or equal to 50 microns.
16. 16 . The holographic imaging system of claim 15 , wherein the diffractive optical element and the polychromatic output are each configured to capture a hologram of an object having a speckle size of less than or equal to 20 microns.
17. 17 . A method of holographic imaging an object, the method comprising: generating a plurality of monochromatic light input wavelengths using a plurality of coherent light sources; modifying, using a polarization maintaining diffuser, a spatial profile of the plurality of monochromatic light input wavelengths to generate a polychromatic output; and providing the polychromatic output to a diffractive optical element for holography.
18. 18 . The method of claim 17 , wherein the polarization maintaining diffuser used to modify the spatial profile of the plurality of monochromatic light input wavelengths to generate a polychromatic output comprises using a multimode optical fiber and wherein a length of the multimode optical fiber does not exceed half of a shortest coherence length of the plurality of monochromatic coherent light sources.
19. 19 . A holographic imaging system comprising: a monochromatic coherent light source, configured to generate a monochromatic input light; a multimode optical fiber configured to receive the monochromatic input light at a first end of the multimode optical fiber, and further configured to provide output light from a second end of the fiber; and a diffractive optical element configured to receive the output light from the second end of the fiber.
20. 20 . The holographic imaging system of claim 19 , wherein a length of the multimode optical fiber does not exceed half of a shortest coherence length of the monochromatic coherent light source.

Description

BACKGROUND Holographic imaging systems capture three-dimensional images (e.g., holograms) of object. The three-dimensional images are formed by the interference of light which is encoded with the three-dimensional information of the object through diffraction of coherent light from the object. Furthermore, holographic imaging systems may display the three-dimensional image, after capture, by illumination of a holography medium with coherent light, such as to form a virtual image to be displayed for an observer. SUMMARY Some embodiments provide for a holographic imaging system comprising: a plurality of monochromatic coherent light sources, configured to generate a plurality of monochromatic light input wavelengths; a polarization preserving diffuser configured to receive the plurality of monochromatic light input wavelengths at a first end of the polarization preserving diffuser, and further configured to provide a polychromatic output as a second end of the fiber; and a diffractive optical element configured to receive polychromatic light from the second end of the fiber. Some embodiments provide for a method of holographic imaging an object, the method comprising: generating a plurality of monochromatic light input wavelengths using a plurality of coherent light sources; modifying, using a polarization maintaining diffuser, a spatial profile of the plurality of monochromatic light input wavelengths to generate a polychromatic output; and providing the polychromatic output to a diffractive optical element for holography. Some embodiments, provide for a holographic imaging system comprising: a monochromatic coherent light source, configured to generate a monochromatic input light; a multimode optical fiber configured to receive the monochromatic input light at a first end of the multimode optical fiber, and further configured to provide output light from a second end of the fiber; and a diffractive optical element configured to receive the output light from the second end of the fiber. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A illustrates an example of a holographic capture system, in accordance with some embodiments of the technology described herein. FIG. 1B is an example of a holographic playback system, in accordance with some embodiments of the technology described herein. FIG. 2 illustrates an example of a holographic capture system with a multimodal optical fiber, in accordance with some embodiments of the technology described herein. FIG. 3A illustrates an example of a single beam reflection holographic capture system, in accordance with some embodiments of the technology described herein. FIG. 3B illustrates an example of a single beam transmission holographic capture system, in accordance with some embodiments of the technology described herein. FIG. 3C illustrates an example of a modified single beam transmission holographic capture system, in accordance with some embodiments of the technology described herein. FIG. 4 illustrates an example of a holographic capture system with a split input multimodal optical fiber, in accordance with some embodiments of the technology described herein. FIG. 5 illustrates an example of a holographic capture system with a shared input multimodal optical fiber, in accordance with some embodiments of the technology described herein. FIG. 6 illustrates an example of a holographic capture system with a holographic diffuser, in accordance with some embodiments of the technology described herein. FIG. 7 illustrates an example of a holographic playback system with a multimodal optical fiber, in accordance with some embodiments of the technology described herein. DETAILED DESCRIPTION The inventor has developed technology to facilitate holography imaging and playback. The technology includes hardware components to generate coherent light and to modify the characteristics of the coherent light to improve the performance of holographic capture and playback. Holographic capture involves recording, in a holographic medium, a representation of an object or scene that includes parallax and depth of the object or scene. In holographic capture, the spatial extent and depth of an object or scene are captured by interfering light scattered off an object from an illumination beam with a reference beam. The scattering of light by the object modifies the phase of the illumination beam, forming an object beam which, upon combining with the reference beam, creates an interference pattern. The modification of the phase in the resulting object beam is indicative of the parallax and depth of the object or scene, which may be recorded in a recording medium. Holographic playback involves illuminating the holographic medium, with an appropriate light source, such that a three-dimensional (3D) virtual image is produced for a holographic display. The quality of the captured hologram, and by extension a hologram display, depends on the characteristics of the coherent light source used during holo