US 12,730,318 B2 · Exit pupil expander with total internal reflection between wedge surfaces

Abstract

An exit pupil expander (EPE) has entrance and exit pupils, a back surface adjacent to the entrance pupil, and an opposed front surface. In one embodiment the EPE is geometrically configured such that light defining a center wavelength that enters at the entrance pupil perpendicular to the back surface experiences angularly varying total internal reflection between the front and back surfaces such that the light exiting the optical channel perpendicular to the exit pupil is at a wavelength shifted from the center wavelength. In another embodiment a first distance at the entrance pupil between the front and back surfaces is different from a second distance at the exit pupil between the front and back surfaces. The EPE may be deployed in a head-wearable imaging device (e.g., virtual or augmented reality) where the entrance pupil in-couples light from a micro display and the exit pupil out-couples light from the EPE.

Claims15

Dependent claims

A method of operating an optical channel comprising:

directing light through an entrance pupil of an optical channel body, wherein an exit pupil enables the light to exit the optical channel body, wherein the optical channel body is geometrically configured such that a front surface and a back surface form a continuous wedge defining an angle α that quantifies an amount of non-parallelism between the front surface and the back surface and between a plane of the entrance pupil and a plane of the exit pupil, a first distance at the entrance pupil between the front surface and the back surface is greater than a second distance at the exit pupil between the front surface and the back surface, and wherein light defining a center wavelength that enters the optical channel body at the entrance pupil perpendicular to the back surface experiences angularly varying total internal reflection between the front and back surfaces such that the light that exits the optical channel body perpendicular to the exit pupil is at a wavelength shifted from the center wavelength.

A method of operating an optical channel comprising:

directing light through an entrance pupil of an optical channel body, wherein the optical channel body is configured such that front and back surfaces of the optical channel form a continuous wedge defining an angle α that quantifies an amount of non-parallelism between the front surface and the back surface and between a plane of the entrance pupil and a plane of the exit pupil, light that enters the optical channel body at the entrance pupil experiences total internal reflection between the front and back surfaces, and a first distance at the entrance pupil between the front surface and the back surface is greater than a second distance at the exit pupil between the front surface and the back surface, wherein the front surface is adjacent to the exit pupil and the optical channel body is a see-through exit pupil expander further comprising:
a compensating wedge disposed adjacent to a portion of the back surface opposite the exit pupil, said compensating wedge transparent to incident environmental light and geometrically configured to offset exit pupil expansion that the optical channel body imposes on incident environmental light that passes into the optical channel body via the compensating wedge.

A method of operating an optical channel comprising a wedge overlay, the method comprising:

directing light through an entrance pupil of an optical channel body, wherein the optical channel body is configured such that front and back surfaces of the optical channel form a continuous wedge defining an angle α that quantifies an amount of non-parallelism between the front surface and the back surface and between a plane of the entrance pupil and a plane of the exit pupil, light that enters the optical channel body at the entrance pupil experiences total internal reflection between the front and back surfaces, and a first distance at the entrance pupil between the front surface and the back surface is greater than a second distance at the exit pupil between the front surface and the back surface, wherein:
the front and back surfaces are front and back surfaces of the optical channel body;
the wedge overlay defines non-parallel front and back overlay surfaces;
the wedge overlay is disposed adjacent to the front surface of the optical channel body opposite the entrance pupil such that the first distance is between the back surface of the optical channel body and the front overlay surface;
and
at least some of the light entering the optical channel body via the entrance pupil is reflected from the front overlay surface back into the optical channel body towards the back surface of the optical channel body.

3 more elements

Dependencies are inferred from the claim text.

Exit pupil expander with total internal reflection between wedge surfaces

Life of this patent

Exit pupil expander with total internal reflection between wedge surfaces

Life of this patent

Abstract

Claims15