Ultra-compact HUD utilizing waveguide pupil expander with surface relief gratings in high refractive index materials
First Claim
Patent Images
1. A head up display, comprising:
- an image source;
a folded catadioptric collimator comprising a fold prism receiving light from the image source, a field lens receiving light from the fold prism, and a beam splitter receiving light from the field lens and redirecting light to a curved reflector, the curved reflector providing collimated light through the beam splitter to an exit surface on the beam splitter, wherein the folded catadioptric collimator is configured to a have a light path from the image source to the exit surface on the beam splitter, the light path having a single bounce within the fold prism as the light travels from the image source to the field lens, wherein the fold prism receives the light directly from the image source;
a bracket; and
a waveguide attached to a planar surface of the bracket, the waveguide having a first diffraction grating at a first end for receiving the collimated light at the exit surface and a second diffraction grating at a second end, the first diffraction grating being an input diffraction grating and the second diffraction grating being an output diffraction grating and the waveguide being positioned as a combiner and allowing viewing of an outside scene and information from the image source, the waveguide having a high index of refraction of greater than 1.6, wherein the first diffraction grating and the second diffraction grating have a period of 330 nm plus or minus 20 percent, wherein the waveguide provides single axis pupil expansion, the single axis pupil expansion provided by the waveguide being on the order of 3 to 8 times, wherein the waveguide comprises a first plate and a second plate and a beam splitting coating disposed between the first plate and the second plate along a line defined by the first plate and the second plate, the line disposed between the first diffraction grating and the second diffraction grating and parallel to main surfaces of the first diffraction grating and the second diffraction grating, the beam splitting coating being configured to cause light entering the waveguide from the image source and traveling from the first diffraction grating to the second diffraction grating via the first and second plates by total internal reflection between the main surfaces to have an increased number of rays propagating to the second diffraction grating.
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Abstract
A head up display include an image source, and a waveguide. The waveguide has a first diffraction grating and a first end and a second diffraction grating at a second end. The waveguide is positioned as a combiner and allows viewing of an outside scene and information from the image source. The first and second diffraction gratings are surface relief gratings having a high index of modulation.
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Citations
20 Claims
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1. A head up display, comprising:
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an image source; a folded catadioptric collimator comprising a fold prism receiving light from the image source, a field lens receiving light from the fold prism, and a beam splitter receiving light from the field lens and redirecting light to a curved reflector, the curved reflector providing collimated light through the beam splitter to an exit surface on the beam splitter, wherein the folded catadioptric collimator is configured to a have a light path from the image source to the exit surface on the beam splitter, the light path having a single bounce within the fold prism as the light travels from the image source to the field lens, wherein the fold prism receives the light directly from the image source; a bracket; and a waveguide attached to a planar surface of the bracket, the waveguide having a first diffraction grating at a first end for receiving the collimated light at the exit surface and a second diffraction grating at a second end, the first diffraction grating being an input diffraction grating and the second diffraction grating being an output diffraction grating and the waveguide being positioned as a combiner and allowing viewing of an outside scene and information from the image source, the waveguide having a high index of refraction of greater than 1.6, wherein the first diffraction grating and the second diffraction grating have a period of 330 nm plus or minus 20 percent, wherein the waveguide provides single axis pupil expansion, the single axis pupil expansion provided by the waveguide being on the order of 3 to 8 times, wherein the waveguide comprises a first plate and a second plate and a beam splitting coating disposed between the first plate and the second plate along a line defined by the first plate and the second plate, the line disposed between the first diffraction grating and the second diffraction grating and parallel to main surfaces of the first diffraction grating and the second diffraction grating, the beam splitting coating being configured to cause light entering the waveguide from the image source and traveling from the first diffraction grating to the second diffraction grating via the first and second plates by total internal reflection between the main surfaces to have an increased number of rays propagating to the second diffraction grating. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of providing information to a pilot, the method comprising:
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providing light associated with the information from an image source using a folded catadioptric collimator comprising a fold prism receiving light from the image source, a field lens receiving light from the fold prism, a beam splitter receiving light from the field lens and redirecting light to a curved reflector, the curved reflector providing collimated light through the beam splitter to an exit surface on the beam splitter, wherein the substrate waveguide is part of a fixed head up display configuration, wherein the folded catadioptric collimator is configured to a have a light path from the image source to the exit surface on the beam splitter, the light path having a single bounce within the fold prism as the light travels from the image source to the field lens, wherein the fold prism receives the light directly from the image source; and diffracting the collimated light at an input of the substrate waveguide using a first surface relief grating into the waveguide and diffracting the light out of the waveguide using a second surface relief grating at an output of the waveguide, wherein the substrate waveguide has a high index of refraction greater than 1.6, and wherein the substrate waveguide comprises a first plate and a second plate, wherein the first plate and the second plate are of equal size. - View Dependent Claims (12, 13, 14, 15)
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16. An optical system for a head up display including an image source, the optical system comprising:
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a combiner, wherein the combiner is positioned to receive light from an image source, wherein the combiner is a waveguide including surface relief diffraction gratings etched into high index of refraction inorganic material, the waveguide having a high index of refraction of greater than 1.6, a first grating of the surface relief diffraction gratings being an input grating and a second grating of the surface relief diffraction gratings being an output grating; and a folded catadioptric collimator disposed adjacent the first grating, wherein the folded catadioptric collimator provides the light to the first grating, the folded catadioptric collimator having a rectangular exit pupil having dimensions of 4 units by 1 unit, the rectangular exit pupil being extended to dimensions of 4 units by 4 units by the combiner, wherein the folded catadioptric collimator comprises a fold prism receiving light from the image source, a field lens receiving light from the fold prism, a beam splitter receiving light from the field lens and redirecting light to a curved reflector, the curved reflector providing collimated light through the beam splitter to an exit surface of the beam splitter for receipt by the input grating, wherein the field lens is disposed at an output face of the fold prism, wherein the folded catadioptric collimator is configured to a have a light path from the image source to the exit surface on the beam splitter, the light path having a single bounce within the fold prism as the light travels from the image source to the field lens, wherein the fold prism receives the light directly from the image source. - View Dependent Claims (17, 18, 19, 20)
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Specification