Systems, devices, and methods for combined angle- and wavelength multiplexing in holographic optical elements (HOE) are described. An angle- and wavelength-multiplexed HOE includes multiple angle-multiplexed sets of wavelength-multiplexed holograms. Each set of wavelength-multiplexed holograms includes at least two holograms that are each responsive to a different wavelength of light. Each angle-multiplexed set of wavelength-multiplexed holograms includes a respective set of wavelength-multiplexed holograms that are all responsive to light that is incident thereon with and angle of incidence that is within a particular range. An example application is described in which an angle- and wavelength-multiplexed HOE is used as a holographic combiner in a wearable heads-up display, where angle-multiplexing provides multiple spatially-separated exit pupils in the eyebox of the display and wavelength-multiplexing provides multiple colors to each respective exit pupil.

A method for displaying a hologram to a variable direction including using circuitry to determine a direction from a holographic projector to a viewer for projecting a hologram to a viewer, and projecting a hologram in the determined direction, in which the projecting the hologram includes reflecting from a same mirror as the determining the direction of the viewer, and the circuitry controls the projecting the hologram to a direction corrected for a difference in direction between a projecting unit and a tracking unit relative to the mirror. Related apparatus and methods are also described.

Examples are disclosed herein relating to an adjustable scanning system configured to adjust light from an illumination source on a per-pixel basis. One example provides an optical system including an array of light sources, a holographic light processing stage comprising, for each light source in the array, one or more holograms configured to receive light from the light source and diffract the light, the one or more holograms being selective for a property of the light that varies based upon the light source from which the light is received, and a scanning optical element configured to receive and scan the light from the holographic light processing stage.

A laser beam (L50) is reflected by a light beam scanning device (60) and irradiated onto a hologram recording medium (45). On the hologram recording medium (45), an image (35) of a linear scatter body is recorded as a hologram by using reference light that converges on a scanning origin (B). The light beam scanning device (60) bends the laser beam (L50) at the scanning origin (B) and irradiates the laser beam onto the hologram recording medium (45). At this time, by changing a bending mode of the laser beam with time, an irradiation position of the bent laser beam (L60) on the hologram recording medium (45) is changed with time. Diffracted light (L45) from the hologram recording medium (45) produces a reproduction image (35) of the linear scatter body on a light receiving surface (R) of the stage 210. When an object is placed on the light receiving surface (R), a line pattern is projected by hologram reproduction light, so that the projected image is captured and a three-dimensional shape of the object is measured.

Systems, devices, and methods for holographic optical elements are described. A holographic optical element includes a first layer of holographic material and a second layer of holographic material. The first layer of holographic material includes a first hologram responsive to light in a first waveband and a second hologram responsive to light in a second waveband. The second layer of holographic material includes a third hologram responsive to light in a third waveband and may include a fourth hologram responsive to light in a fourth waveband. The first, second, third, and fourth wavebands are distinct and may comprise light of red, blue, green, and infrared wavelengths, respectively. Distribution of the three or four holograms on two layers of holographic material allows each hologram to have an index modulation of greater than 0.016, a diffraction efficiency of greater than 15%, and an angular bandwidth of greater than 12.

Systems, devices, and methods for holographic optical elements are described. A holographic optical element includes a first layer of holographic material and a second layer of holographic material. The first layer of holographic material includes a first hologram responsive to light in a first waveband and a second hologram responsive to light in a second waveband. The second layer of holographic material includes a third hologram responsive to light in a third waveband and may include a fourth hologram responsive to light in a fourth waveband. The first, second, third, and fourth wavebands are distinct and may comprise light of red, blue, green, and infrared wavelengths, respectively. Distribution of the three or four holograms on two layers of holographic material allows each hologram to have an index modulation of greater than 0.016, a diffraction efficiency of greater than 15%, and an angular bandwidth of greater than 12.

Systems, devices, and methods for holographic optical elements are described. A holographic optical element includes a first layer of holographic material and a second layer of holographic material. The first layer of holographic material includes a first hologram responsive to light in a first waveband and a second hologram responsive to light in a second waveband. The second layer of holographic material includes a third hologram responsive to light in a third waveband and may include a fourth hologram responsive to light in a fourth waveband. The first, second, third, and fourth wavebands are distinct and may comprise light of red, blue, green, and infrared wavelengths, respectively. Distribution of the three or four holograms on two layers of holographic material allows each hologram to have an index modulation of greater than 0.016, a diffraction efficiency of greater than 15%, and an angular bandwidth of greater than 12.

An anisotropic spatial acousto-optic modulator for a holographic display system includes a substrate, an anisotropic waveguide that guides light into a single polarization, and a transducer that generates surface acoustic waves that propagate linearly with the guided, polarized light, converting at least some of the polarized light into a leaky mode of orthogonally polarized light. The acoustic waves may be encoded with holographic information. The modulator may include coupling devices for coupling light into the waveguide, which may have multiple channels. A holographic video display system includes at least one anisotropic spatial acousto-optic modulator. The pattern of the surface acoustic waves, encoded with holographic information, acts as a diffraction pattern that causes the modulator output to form a wavefront that becomes at least part of a holographic image. The system may have multiple channels in multiple waveguides, wherein each waveguide writes one or more lines of the holographic image.

An electro-holographic light field generator device comprises surface acoustic wave (SAW) optical modulators arranged in different directions. Specifically, some embodiments have SAW modulators arranged in pairs, nose-to-nose with each other, and have output couplers that provide face-fire light emission. These SAW modulators also possibly include SAW sense transducers and/or viscoelastic surface material to reduce crosstalk.

An electro-holographic light field generator device comprises surface acoustic wave (SAW) optical modulators arranged in different directions. Specifically, some embodiments have SAW modulators arranged in pairs, nose-to-nose with each other, and have output couplers that provide face-fire light emission. These SAW modulators also possibly include SAW sense transducers and/or viscoelastic surface material to reduce crosstalk.