Augmented reality device based on waveguide with holographic diffractive grating structure and apparatus for recording the holographic diffractive grating structure

An augmented reality (AR) device for displaying AR, the AR device comprising:

• a projection system;
• an input diffractive element;
• and
• a waveguide comprising a holographic diffractive grating structure that comprises an expanded diffractive structure and an out-coupling diffractive grating,
• wherein the expanded diffractive grating has a shape of a first interference pattern formed in a depth direction on a first surface of a diffractive grating material applied to the waveguide,
• wherein the out-coupling diffractive grating has a shape of a second interference pattern formed in a depth direction on a second surface of the diffractive grating material, the second surface opposing the first surface,
• wherein the shape of the first interference pattern is formed such that a maximum intensity and a minimum intensity of the first interference pattern are formed vertically in the depth direction on the first surface of the diffractive grating material, and
• wherein the shape of the second interference pattern is formed such that a maximum intensity and a minimum intensity of the second interference pattern are formed at an angle in the depth direction on the second surface of the diffractive grating material, the second surface opposing the first surface.

An apparatus for recording a holographic diffractive grating structure, the apparatus comprising:

• a light source configured to output light;
• a beam splitter configured to split the light into a first light beam and a second light beam;
• a first expander, a first amplitude filter, and a first triangular prism that are provided on a path of the first light beam;
• and
• a second expander, a second amplitude filter, and a second triangular prism that are provided on a path of the second light beam,
• wherein the first amplitude filter is configured to direct a first part of the first light beam directly to the first triangular prism and direct a second part of the first light beam, which is different from the first part to the first triangular prism after passing through the first amplitude filter,
• wherein the first triangular prism comprises a first surface on which the first part of the first light beam is incident, a second surface on which the second part of the first light beam is incident, and a first exit surface through which the first part of the first light beam and the second part of the first light beam exits,
• wherein the second triangular prism comprises a first surface on which the second light beam that passes the second amplitude filter is incident and a second exit surface through which the second light beam exits,
• wherein the second exit surface of the second triangular prism is spaced apart from and parallel to the first exit surface of the first triangular prism, and
• wherein a diffractive grating material for recording the holographic diffractive grating structure is provided between the first exit surface and the second exit surface.