Systems, devices, and methods for aperture-free hologram recording are described. 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.

Various embodiments are generally directed to techniques for processing holographic recording media. Some embodiments are particularly directed to processing a raw holographic recording medium into an apodized holographic recording medium. For example, a raw holographic recording medium may include a plurality of photosensitive molecules uniformly distributed throughout that are able to record an interference pattern to create a hologram. However, when a photosensitive molecule is desensitized, such as by exposure to incoherent light, its photosensitivity is lost and the molecule may no longer be able to record an interference pattern of coherent light. Various embodiments described herein may include an apodized holographic recording medium that has been exposed to incoherent light in a manner to desensitize some photosensitive molecules therein such that the remaining photosensitive molecules have a non-uniform distribution.

A backlight device, a holographic display that includes the backlight device, and a method of manufacturing a holographic optical element are provided. The backlight device includes a light guide plate configured to guide light emitted by a light source, a first holographic optical element configured to expand light that has propagated through the light guide plate and that has a multi-layered structure, and a second holographic optical element configured to concentrate light reflected by the first holographic optical element.

Systems, devices, and methods for making, replicating, and using curved holographic optical elements (HOEs) are described. A hologram may be optically recorded into a planar layer of holographic film with various measures in place to compensate for changes (e.g., in optical power and/or playback wavelength and/or angular bandwidth) that may result when a curvature is subsequently applied thereto. A hologram may be optically recorded into a curved layer of holographic film with various measures in place to compensate for optical effects of a curved transparent substrate upon which the holographic film is mounted. A curved HOE may be returned to a planar configuration to undergo holographic replication or holographic replication may be performed using a curved master HOE and curved recipient film. The curved HOEs described herein are particularly well-suited for use when integrated with a curved eyeglass lens to form the transparent combiner of a virtual retina display.

Systems, devices, and methods for making, replicating, and using curved holographic optical elements (HOEs) are described. A hologram may be optically recorded into a planar layer of holographic film with various measures in place to compensate for changes (e.g., in optical power and/or playback wavelength and/or angular bandwidth) that may result when a curvature is subsequently applied thereto. A hologram may be optically recorded into a curved layer of holographic film with various measures in place to compensate for optical effects of a curved transparent substrate upon which the holographic film is mounted. A curved HOE may be returned to a planar configuration to undergo holographic replication or holographic replication may be performed using a curved master HOE and curved recipient film. The curved HOEs described herein are particularly well-suited for use when integrated with a curved eyeglass lens to form the transparent combiner of a virtual retina display.

Systems, devices, and methods for making, replicating, and using curved holographic optical elements (HOEs) are described. A hologram may be optically recorded into a planar layer of holographic film with various measures in place to compensate for changes (e.g., in optical power and/or playback wavelength and/or angular bandwidth) that may result when a curvature is subsequently applied thereto. A hologram may be optically recorded into a curved layer of holographic film with various measures in place to compensate for optical effects of a curved transparent substrate upon which the holographic film is mounted. A curved HOE may be returned to a planar configuration to undergo holographic replication or holographic replication may be performed using a curved master HOE and curved recipient film. The curved HOEs described herein are particularly well-suited for use when integrated with a curved eyeglass lens to form the transparent combiner of a virtual retina display.

Systems, devices, and methods for making, replicating, and using curved holographic optical elements (HOEs) are described. A hologram may be optically recorded into a planar layer of holographic film with various measures in place to compensate for changes (e.g., in optical power and/or playback wavelength and/or angular bandwidth) that may result when a curvature is subsequently applied thereto. A hologram may be optically recorded into a curved layer of holographic film with various measures in place to compensate for optical effects of a curved transparent substrate upon which the holographic film is mounted. A curved HOE may be returned to a planar configuration to undergo holographic replication or holographic replication may be performed using a curved master HOE and curved recipient film. The curved HOEs described herein are particularly well-suited for use when integrated with a curved eyeglass lens to form the transparent combiner of a virtual retina display.

The subject matter described herein includes a curved VPH grating with tilted fringes and spectrographs, both retroreflective and transmissive, that use such gratings. A VPH grating according to the subject matter described herein includes a first curved surface for receiving light to be diffracted. The grating includes an interior region having tilted fringes to diffract light that passes through the first surface. The grating further includes a second curved surface bounding the interior region on a side opposite the first surface and for passing light diffracted by the fringes.

The present invention provides a visible light photoinitiating system for preparing a holographic photopolymer material with high-diffraction efficiency. The photoinitiating system comprises a photosensitizer and a co-initiator, and its mechanism is that the photosensitizer transforms from ground state to excited state after absorbing photons, and then interacts with the co-initiator through transfer of electrons and protons, which produces an alkyl (or aryl) free radical R and a ketyl radical K; wherein the free radical R initiates the addition polymerization of monomers that are capable of free radical polymerization, whereas the radical K inhibits the chain propagation of the macromolecular free radicals to a certain degree due to the steric hindrance effect, and thus delays the gelation time of the photopolymerization, which helps to increase the phase separation between the polymer and the functional components. A holographic photopolymer material with high-diffraction efficiency can be obtained by employing this visible light photoinitiating system.

We describe a window assembly comprising: a window pane comprising a glass or plastic sheet; and a layer of holographic recording medium attached to said glass or plastic sheet; wherein said layer of holographic recording medium has recorded within the medium a volume hologram configured to direct light incident onto said glass or plastic sheet to propagate within a thickness of said glass or plastic sheet. In embodiments the volume hologram is fabricated by recording a transmission hologram and shrinking the recorded hologram to convert the transmission hologram to an edge-directing hologram configured to direct light in a direction to be totally internally reflected within the window pane, for example at greater than 40, 50, 60, 70, 75 or 80 to a normal to the surface of the hologram.