Flat-panel optical projection apparatus
First Claim
1. A light guide comprising:
- an input slab having an input slab input face and a second input slab face; and
an output waveguide to receive rays from the input slab, and to emit the rays through an output face, the output waveguide having the output face and a second output waveguide face, wherein a thickness of the input slab tapers at a constant first angle in a direction of ray travel and a thickness of the output waveguide between the output face and the second output waveguide face tapers at a second angle that is different from the first angle, in which the second angle at which the output waveguide taper increases in the direction of wave travel, the input slab being configured so a steepest possible propagating ray entering the input slab through the input slab input face and propagating to the output waveguide reflects off the second input slab face, the output waveguide being configured so a second propagating ray entering the input slab through the input slab input face and propagating to the output waveguide reflects off the second output waveguide face.
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Abstract
A light guide of the tapered-waveguide type includes an input slab for expanding a projected image between an input end and an output end, and an output slab arranged to receive rays from the said output end, and to emit them at a point on its face that corresponds to the angle at which the ray is received. The input slab and output waveguide are matched so that all rays injected into the input end undergo the same number of reflections before leaving the output surface. With the invention, the input slab is itself tapered slightly towards the output waveguide. This means that input and output waveguides can be made the same length, in the direction of ray travel, and can therefore be folded over each other with no wasted space.
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Citations
18 Claims
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1. A light guide comprising:
an input slab having an input slab input face and a second input slab face; and
an output waveguide to receive rays from the input slab, and to emit the rays through an output face, the output waveguide having the output face and a second output waveguide face, wherein a thickness of the input slab tapers at a constant first angle in a direction of ray travel and a thickness of the output waveguide between the output face and the second output waveguide face tapers at a second angle that is different from the first angle, in which the second angle at which the output waveguide taper increases in the direction of wave travel, the input slab being configured so a steepest possible propagating ray entering the input slab through the input slab input face and propagating to the output waveguide reflects off the second input slab face, the output waveguide being configured so a second propagating ray entering the input slab through the input slab input face and propagating to the output waveguide reflects off the second output waveguide face.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A light guide comprising:
an input slab having a first end, a second end, and an input slab face the input slab having a constant angle of taper from the first end to the second end; and
an output waveguide to receive light rays from the input slab, and emit the light rays through an output face, the output waveguide having the output face and an output waveguide face, the output waveguide having an angle of taper between the output face and the output waveguide face in a direction of ray travel, the constant angle of taper of the input slab being different than the angle of taper of the output waveguide, in which the angle of taper of the output waveguide increases in the direction of ray travel, the input slab being configured so a steepest possible propagating ray entering the input slab through the first end and propagating to the output waveguide reflects off the input slab face, the output waveguide being configured so a second propagating ray entering the input slab through the first end and propagating to the output waveguide reflects off the output waveguide face.- View Dependent Claims (10, 11, 12, 13, 14)
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15. An apparatus comprising:
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an input slab to receive light rays at an input end, the input slab decreasing in thickness from the input end to an output end at a first angle of taper, and having an input slab face; an output slab having an entrance end to receive the light rays from the output end of the input slab, the output slab having an output face to emit the light rays, the output slab having an output slab face, the output slab decreasing in thickness between the output face and the output slab face from the entrance end at a second angle of taper different from the first angle of taper, the input slab being configured so a steepest possible propagating ray entering the input slab through the input end and propagating to the output slab reflects off the input slab face, the output slab being configured so a second propagating ray entering the input slab through the input end and propagating to the output slab reflects off the output slab face. - View Dependent Claims (16, 17, 18)
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Specification