An optical device includes an optical component (e.g., a polarization volume hologram, a geometric phase device, or a polarization-insensitive diffractive optical element) having a uniform thickness and configured to modify a wavefront of a light beam that includes light in two or more wavelengths visible to human eyes, where the optical component has a chromatic aberration between the two or more wavelengths. The optical device also includes a metasurface on the optical component. The metasurface includes a plurality of nanostructures configured to modify respective phases of incident light at a plurality of regions of the metasurface, where the plurality of nanostructures is configured to, at each region of the plurality of regions, add a respective phase delay for each of the two or more wavelengths to correct the chromatic aberration between the two or more wavelengths.

An optical device includes an optical component (e.g., a polarization volume hologram, a geometric phase device, or a polarization-insensitive diffractive optical element) having a uniform thickness and configured to modify a wavefront of a light beam that includes light in two or more wavelengths visible to human eyes, where the optical component has a chromatic aberration between the two or more wavelengths. The optical device also includes a metasurface on the optical component. The metasurface includes a plurality of nanostructures configured to modify respective phases of incident light at a plurality of regions of the metasurface, where the plurality of nanostructures is configured to, at each region of the plurality of regions, add a respective phase delay for each of the two or more wavelengths to correct the chromatic aberration between the two or more wavelengths.

A method for determining the validity of a parallax image, comprising: receiving a captured two-dimensional image of a parallax image having at least three target identifiers, where at least two target identifiers are located at different depth planes in the parallax image; identifying the at least three target identifiers in the captured two-dimensional image of the parallax image and determining the spatial relationship between the at least three target identifiers in the two-dimensional image of the parallax image; comparing the spatial relationship of the at least three target identifiers in the captured two-dimensional image of the parallax image against a predetermined spatial relationship of the at least three target identifiers that indicates authenticity; and adjudicating the authenticity of the parallax image based on the degree of difference between the spatial relationship of the at least three target identifiers in the captured two-dimensional image of the parallax image and the predetermined spatial relationship of the at least three target identifiers.

A method for determining the validity of a parallax image, comprising: receiving a captured two-dimensional image of a parallax image having at least three target identifiers, where at least two target identifiers are located at different depth planes in the parallax image; identifying the at least three target identifiers in the captured two-dimensional image of the parallax image and determining the spatial relationship between the at least three target identifiers in the two-dimensional image of the parallax image; comparing the spatial relationship of the at least three target identifiers in the captured two-dimensional image of the parallax image against a predetermined spatial relationship of the at least three target identifiers that indicates authenticity; and adjudicating the authenticity of the parallax image based on the degree of difference between the spatial relationship of the at least three target identifiers in the captured two-dimensional image of the parallax image and the predetermined spatial relationship of the at least three target identifiers.

The apertures typically used for hologram recording create unwanted secondary holograms by diffracting light. Aperture-free hologram recording eliminates these unwanted secondary holograms. Aperture-free hologram recording includes applying a mask to the holographic recording medium. The mask controls the size of the recorded hologram like an aperture but does not create unwanted secondary holograms. Hologram fringes are only present in the desired recording area and a thin boundary region. The mask may be present during recording, or the mask may be used to pre-bleach the holographic recording medium. Pre-bleaching the holographic recording medium renders a portion of the holographic recording medium insensitive to light, the hologram is recorded in the light-sensitive portions of the holographic recording medium.

A method of recording multiple holograms into a holographic recording medium includes exposing the medium to a first light to cause changes in a first refractive index of at least a portion of a first layer of the medium to write a first hologram in the first layer without changing a second refractive index of a second layer of the recording medium. The method also includes exposing the medium to a second light to cause changes in a second refractive index of at least a portion of the second layer to write a second hologram in the second layer. The first layer may include a first photo-polymerizable composition polymerizable by the first light, and the second layer may include a second photo-polymerizable composition polymerizable by the second light and not polymerizable by the first light.

A method of recording multiple holograms into a holographic recording medium includes exposing the medium to a first light to cause changes in a first refractive index of at least a portion of a first layer of the medium to write a first hologram in the first layer without changing a second refractive index of a second layer of the recording medium. The method also includes exposing the medium to a second light to cause changes in a second refractive index of at least a portion of the second layer to write a second hologram in the second layer. The first layer may include a first photo-polymerizable composition polymerizable by the first light, and the second layer may include a second photo-polymerizable composition polymerizable by the second light and not polymerizable by the first light.

A method for determining the validity of a parallax image, including: receiving a parallax image's captured two-dimensional image having at least three target identifiers, where at least two target identifiers are located at different depth planes in the parallax image; identifying at least three target identifiers in the parallax image's captured two-dimensional image and determining spatial relationship between at least three target identifiers in the two-dimensional image of the parallax image; comparing the spatial relationship of at least three target identifiers in the parallax image's captured two-dimensional image against a predetermined spatial relationship of at least three target identifiers that indicates authenticity; and adjudicating the authenticity of the parallax image based on the degree of difference between spatial relationship of at least three target identifiers in the parallax image's captured two-dimensional image and the predetermined spatial relationship of at least three target identifiers.

A method for determining the validity of a parallax image, including: receiving a parallax image's captured two-dimensional image having at least three target identifiers, where at least two target identifiers are located at different depth planes in the parallax image; identifying at least three target identifiers in the parallax image's captured two-dimensional image and determining spatial relationship between at least three target identifiers in the two-dimensional image of the parallax image; comparing the spatial relationship of at least three target identifiers in the parallax image's captured two-dimensional image against a predetermined spatial relationship of at least three target identifiers that indicates authenticity; and adjudicating the authenticity of the parallax image based on the degree of difference between spatial relationship of at least three target identifiers in the parallax image's captured two-dimensional image and the predetermined spatial relationship of at least three target identifiers.

The apertures typically used for hologram recording create unwanted secondary holograms by diffracting light. Aperture-free hologram recording eliminates these unwanted secondary holograms. Aperture-free hologram recording includes applying a mask to the holographic recording medium. The mask controls the size of the recorded hologram like an aperture but does not create unwanted secondary holograms. Hologram fringes are only present in the desired recording area and a thin boundary region. The mask may be present during recording, or the mask may be used to pre-bleach the holographic recording medium. Pre-bleaching the holographic recording medium renders a portion of the holographic recording medium insensitive to light, the hologram is recorded in the light-sensitive portions of the holographic recording medium.