Method and apparatus for recording one-step, full-color, full-parallax, holographic stereograms
View Patent ↗Holographic stereograms and holographic optical elements are printed using computer rendered images of three-dimensional computer models or using computer processed images. A coherent beam is split into object and reference beams that interfere with each other at an elemental hologram on a holographic recording material. A voxel-control lens placed in the path of the object beam and in close proximity to the holographic recording material can be used to control the resolution of a holographic stereogram. Interchangable band-limited diffusers and reference-beam masking plates can assist exposure of the elemental hologram and avoid exposing portions of the holographic recording material that are not part of the elemental hologram.
1. An apparatus comprising:
a light source configured to produce a coherent beam;
a beam splitter configured to split the coherent beam into an object beam, and
a reference beam;
a material holder configured to hold a holographic recording material;
an object beam unit configured to display a rendered image,
condition the object beam with the rendered image, and
cause the object beam to interfere with the reference beam at a location for an elemental hologram of a holographic stereogram on the holographic recording material;
a voxel-control lens located in a path of the object beam and positioned at a distance from the location for the elemental hologram, wherein the distance is based at least in part on
a focal length of the voxel-control lens, and
a size of the elemental hologram; and
a computer programmed to control a delivery of the rendered image to the object beam unit.
2. The apparatus of claim 1 , wherein:
the object beam unit comprises a spatial light modulator (SLM) configured to display the rendered image; and
the voxel-control lens has a focal length about equal to a distance between the voxel-control lens and the SLM.
3. The apparatus of claim 1 , wherein:
the object beam unit comprises a SLM configured to display the rendered image; and
the voxel-control lens has a focal length about equal to a distance between the voxel-control lens and a projected image of the SLM.
4. A method comprising:
selecting a location for an elemental hologram of a holographic stereogram in a holographic recording medium;
generating a coherent light beam;
splitting the beam into
an object beam, and
a reference beam;
rendering an image;
conditioning the object beam with the rendered image, wherein the conditioning comprises
positioning a voxel-control lens at a distance from the selected location for the elemental hologram, wherein the positioning is based at least in part on
a focal length of the voxel-control lens, and
a size of the elemental hologram, and
passing the object beam through the voxel-control lens; and
interfering the conditioned object beam with the reference beam at the selected location for the elemental hologram.
5. The method of claim 4 , wherein the voxel-control lens is positioned at a location selected to:
change the size of at least one voxel of the holographic stereogram; and
make the rendered image, from a viewpoint of the selected location for the elemental hologram, appear at a greater apparent distance relative to the holographic recording material.
6. The method of claim 4 , wherein:
the conditioning comprises displaying the rendered image on a spatial light modulator (SLM); and
the focal length of the voxel-control lens is about equal to a distance between the voxel-control lens and the SLM.
7. The method of claim 4 , wherein:
the conditioning comprises displaying the rendered image on a spatial light modulator (SLM); and
the focal length of the voxel-control lens is about equal to a distance between the voxel-control lens and a projected image of the SLM.
8. A system comprising:
means for generating a coherent light beam;
means for splitting the beam into
an object beam, and
a reference beam;
means for rendering an image;
means for conditioning the object beam with the rendered image, comprising
an object beam unit, wherein
the object beam unit is configured to position a voxel-control lens at a distance from a selected location for an elemental hologram of a holographic stereogram,
the elemental hologram is in a holographic recording medium,
the distance is based at least in part on
a focal length of the voxel-control lens, and
a size of the elemental hologram, and
means for passing the object beam through the voxel-control lens; and
means for interfering the conditioned object beam with the reference beam at the selected location for the elemental hologram.
9. The system of claim 8 , wherein the object beam unit is configured to position the voxel-control lens at a location selected to:
change the size of at least one voxel of the holographic stereogram; and
make the rendered image, from a viewpoint of the selected location for the elemental hologram, appear at a greater apparent distance relative to the holographic recording material.
10. The system of claim 8 , wherein:
the means for conditioning the object beam with the rendered image comprises means for displaying the rendered image on a spatial light modulator (SLM); and
the focal length of the voxel-control lens is about equal to a distance between the voxel-control lens and the SLM.
11. The system of claim 8 , wherein:
the means for conditioning the object beam with the rendered image comprises means for displaying the rendered image on a spatial light modulator (SLM); and
the focal length of the voxel-control lens is about equal to a distance between the voxel-control lens and a projected image of the SLM.