Illuminator for a wearable display
A compact illuminator for a see-through image display system with highly uniform light distribution is disclosed. This invention enables wearable displays such as eye-glass type see-through display. This system provides a wide divergent beam from a display device so that a viewer can have a large eyebox.
1. A see-through display system comprising:
a display device comprising a LCOS with a circuit to drive the LCOS;
an eyeglass lens and a temple;
a see-through optical element comprises a group of holographic optical element (HOE) and diffractive optical element (DOE) attached to the eyeglass lens;
a projection optics embedded in the temple having at least one lens with at least one free form surface and at least one mirror projecting image light beams through air to the eyeglass;
an illuminator comprising a light source of multiple colors having light emitting device(s) from a group of Laser, LED, OLED and phosphor activated by a solid state light source;
an optical combiner combining the light sources of multiple colors into a single beam wherein said combiner is from a group of dichroic prism, PBS, optical fiber, free form lenses, DOE, HOE and planar light waveguide circuit and Total Internal Reflection (TIR) prism wherein the incident angle of said combined light beam onto said display device is larger than 10 degrees; and
the LCOS comprises a cubic polarized beam splitter (PBS) that includes two triangular prisms having a layer of polarizer on a splitter face and a ¼ λ retarder parallel to the LCOS display surface and on the opposite side of face of said PBS from LCOS, so that a single PBS can transmit necessary image light to a projection lens.
2. The see-through display system of claim 1 wherein:
the combiner further combines beams of the light sources with dichroic prisms into a light pipe includes a group of rectangular tube having higher refractive index than air and an optical fiber.
3. The see-through display system of claim 1 wherein:
the combiner further combines beams of the light sources with a polarized beam splitter into a light pipe includes a group of rectangular tube having higher refractive index than air and an optical fiber.
4. The see-through display system of claim 1 further comprising:
a group of light pipe, micro-lens-array and diffuser plate placed between the combiner and display device.
5. The display system of claim 1 wherein:
the combiner comprising optical elements include a group of Diffractive Optical Element (DOE) and Holographic Optical Element (HOE) to direct light beams from said light sources into a light guide from a group of light pipe, optical fiber and diffuser plate.
6. An illuminator for a wearable display comprising:
a display device of LCOS;
a circuit to drive said display device;
an eyeglass lens and a temple;
an illuminator comprising a light source of multiple colors having light emitting device(s) from a group of Laser, LED and OLED;
a micro-lens-array to condense light beams containing multiple wavelengths;
an optical combiner combining the light sources of multiple colors into a single beam wherein said combiner comprises a polarized beam splitter (PBS) wherein the incident angle of said combined light beam onto said display device is larger than 20 degrees; and
the PBS is a cross prism having a first polarizer passing P-wave and reflecting S-wave in a diagonal internal surface and a second polarizer passing S-wave and reflecting P-wave in another diagonal internal surface perpendicular to the first polarizer.
7. The illuminator of claim 6 wherein:
the micro-lens-array is an array of DOE from a group of holographic optical element and diffractive optical element.
8. The illuminator of claim 6 wherein:
the micro-lens-array is an array of free-form lenses.