Bragg gratings for an augmented reality display system

A head-mounted display system configured to be worn by a user comprising:

• a head-mountable frame;
• a light projection system configured to output light to provide image content to the user's eye;
• a waveguide supported by the frame, the waveguide configured to guide at least a portion of the light from the light projection system coupled into the waveguide to present said image content to said user's eye;
• and
• a grating comprising:
• a first reflective diffractive optical element comprising a volume phase holographic grating;
• and
• a second reflective diffractive optical element comprising a liquid crystal polarization grating,
• wherein a combination of the first and second reflective diffractive optical elements are disposed on one side of the waveguide and are configured to operate as a transmissive diffractive optical element,
• wherein the first reflective diffractive optical element comprising the volume phase holographic grating is configured to reflect light directed toward the first reflective diffractive optical element toward the second reflective diffractive opticalelement,
• wherein the second reflective diffractive optical element comprising the liquid crystal polarization grating is configured to reflect light reflected by the first reflective diffractive optical element back toward said first reflective diffractive optical element, and
• wherein the first reflective diffractive optical element is configured to transmit light reflected by the second reflective diffractive optical element.

A head-mounted display system configured to be worn by a user comprising:

• a head-mountable frame;
• a light projection system configured to output light to provide image content to the user's eye;
• a waveguide supported by the frame, the waveguide configured to guide at least a portion of the light from the light projection system coupled into the waveguide to present said image content to said user's eye;
• and
• a grating comprising:
• a first reflective diffractive optical element comprising a volume phase holographic grating;
• and
• a second reflective diffractive optical element comprising a liquid crystal polarization grating,
• wherein a combination of the first and second reflective diffractive optical elements are disposed on one side of the waveguide and are configured to operate as a transmissive diffractive optical element, and
• wherein the first reflective diffractive optical element comprising the volume phase holographic grating is configured to reflect light at a particular incident angle and transmit light at other incident angles.

A head-mounted display system configured to be worn by a user comprising:

• a head-mountable frame;
• a light projection system configured to output light to provide image content to the user's eye;
• a waveguide supported by the frame, the waveguide configured to guide at least a portion of the light from the light projection system coupled into the waveguide to present said image content to said user's eye;
• and
• a grating comprising:
• a first reflective diffractive optical element comprising a volume phase holographic grating;
• and
• a second reflective diffractive optical element comprising a liquid crystal polarization grating,
• wherein a combination of the first and second reflective diffractive optical elements are disposed on one side of the waveguide and are configured to operate as a transmissive diffractive optical element,
• wherein the second reflective diffractive optical element comprising the liquid crystal polarization grating is configured to transmit incident light having a first polarization state and reflect incident light polarized having a second different polarization state, and
• wherein the first polarization state comprises a linear polarization state and the second polarization state comprises a circular polarization state.

A head-mounted display system configured to be worn by a user comprising:

• a head-mountable frame;
• a light projection system configured to output light to provide image content to the user's eye;
• a waveguide supported by the frame, the waveguide configured to guide at least a portion of the light from the light projection system coupled into the waveguide to present said image content to said user's eye;
• and
• a grating comprising:
• a first reflective diffractive optical element comprising a volume phase holographic grating;
• and
• a second reflective diffractive optical element comprising a liquid crystal polarization grating,
• wherein a combination of the first and second reflective diffractive optical elements are disposed on one side of the waveguide and are configured to operate as a transmissive diffractive optical element, and
• wherein the polarization state of light is changed as a result of reflection of the light by the first reflective diffractive optical element comprising the volume phase holographic grating.