Systems, devices, and methods for side lobe control in holograms
AssigneeGoogle Inc.
InventorRobin W. Tsen
Life of this patent
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Abstract
Systems, devices, and methods for side lobe control in holograms are described. The magnitude of the side lobes of a hologram depends on the distribution of refractive index modulation (Δn), therefore control of side lobe magnitude may be achieved by controlling the distribution of Δn. The distribution of Δn may be controlled by replicating a hologram from a master with two reference beams, where the wavelength and angle of each reference beam, the playback angle of the master hologram, and the thickness of the master hologram, the copy holographic recording medium (HRM), and the recording substrate are carefully chosen to achieve a pattern of meta-interference within the HRM that matches the desired distribution of Δn.
Claims21
A hologram comprising:
- a first set of fringes within a volume of the hologram, the first set of fringes comprising a first fringe phase, a first fringe spacing, and a first fringe slant angle;
- and
- a second set of fringes within the volume of the hologram, the second set of fringes comprising a net phase shift relative to the first fringe phase, a second fringe spacing, and a second fringe slant angle,
- wherein the second fringe spacing is equal to the first fringe spacing, the second fringe slant angle is different from the first fringe slant angle, the first set of fringes and the second set of fringes are configured to meta-interfere, and a magnitude of a refractive index modulation within the hologram varies between a first surface and a second surface of the hologram based on the net phase shift between the first set of fringes and the second set of fringes,
- wherein the magnitude of the refractive index modulation is at a minimum in the hologram at the first surface and the second surface and at a maximum in the hologram at a middle point between the first surface and the second surface.
An eyeglass lens comprising:
- a hologram comprising:
- a first set of fringes within a volume of the hologram comprising a first fringe spacing and a first fringe slant angle;
- and
- a second set of fringes within the volume of the hologram, the second set of fringes comprising a net phase shift relative to a first phase of the first set of fringes, a second fringe spacing, and a second fringe slant angle,
- wherein the second fringe spacing is equal to the first fringe spacing, the second fringe slant angle is different from the first fringe slant angle, the first set of fringes and the second set of fringes are configured to meta-interfere, and a magnitude of a refractive index modulation within the hologram varies between a first surface and a second surface of the hologram based on the net phase shift between the first set of fringes and the second set of fringes,
- wherein the magnitude of the refractive index modulation is at a minimum in the hologram at the first surface and the second surface and at a maximum in the hologram at a middle point between the first surface and the second surface;
- and
- at least one lens portion is physically coupled to the hologram.
A wearable heads-up display, comprising:
- a transparent combiner comprising:
- a hologram comprising:
- a first set of fringes within a volume of the hologram, the first set of fringes comprising a first fringe spacing and a first slant angle;
- and
- a second set of fringes within the volume of the hologram, the second set of fringes comprising a second fringe spacing and a second slant angle,
- wherein the second fringe spacing is equal to the first fringe spacing, the second slant angle is different from the first slant angle, the first set of fringes and the second set of fringes are configured to meta-interfere, and a magnitude of a refractive index modulation within the hologram varies between a first surface and a second surface of the hologram based on a net phase shift between the first set of fringes and the second set of fringes,
- wherein the magnitude of the refractive index modulation is at a minimum in the hologram at the first surface and the second surface and at a maximum in the hologram at a middle point between the first surface and the second surface;
- and
- at least one lens portion physically coupled to the hologram.
Dependencies are inferred from the claim text.