An optical device is provided that comprises a multi-order diffractive Fresnel lens (MOD-DFL) and an achromatizing compensation mechanism that reduces refractive dispersion created by the MOD-DFL, thereby reducing the focal range of the MOD-DFL. A method is also provided of using the optical device in an image processing system to obtain images of an object and processing the images to perform image enhancement.

A multi-functional diffractive optical element (DOE) for redirecting light into a waveguide and providing higher order aberration correction is described. The multi-functional DOE may be positioned on, connected to, adjacent to, or within a waveguide, and in some examples is positioned at, or near, the exit pupil of the projector lens. In an example, a head-mounted display (HMD) is configured to output artificial reality content, comprising a waveguide configured to receive input light and configured to output the received input light to an eyebox. The HMD further comprises a projector configured to input light into the waveguide, the projector comprising a display, a projection lens, and a multi-functional diffractive optical element (DOE) configured to redirect light from the projector into the waveguide and provide higher order aberration correction of the light from the display.

A multilayer grating is a diffraction grating that includes a plurality of layers. The plurality of layers arranged to form a 2-dimensional grating, the layers including at least a first patterned layer and a second patterned layer. The first patterned layer includes a plurality of different materials that are arranged in a first pattern such that the first patterned layer has a first index profile. The second patterned layer includes a plurality of different materials that are arranged in a second pattern such that the second patterned layer has a second index profile that is inverted relative to the first index profile. Ambient light incident on the first patterned layer and the second patterned layer creates a first diffracted ray and a second diffracted ray, respectively, and the first diffracted ray and the second diffracted ray destructively interfere with each other based in part on the inverted index profile.

Methods to build multi-functional scattering structures while respecting tight requirements imposed by manufacturing processes are described. The described methods and devices are based on etching away wire networks embedded in 3D structures to form voids in order to perform a target function. Optimization algorithms for designing binarized devices that meet manufacturing requirements are also disclosed.

A multilayer grating is a diffraction grating that includes a plurality of layers. The plurality of layers arranged to form a 2-dimensional grating, the layers including at least a first patterned layer and a second patterned layer. The first patterned layer includes a plurality of different materials that are arranged in a first pattern such that the first patterned layer has a first index profile. The second patterned layer includes a plurality of different materials that are arranged in a second pattern such that the second patterned layer has a second index profile that is inverted relative to the first index profile. Ambient light incident on the first patterned layer and the second patterned layer creates a first diffracted ray and a second diffracted ray, respectively, and the first diffracted ray and the second diffracted ray destructively interfere with each other based in part on the inverted index profile.

Reflection mode VHOEs are designed and fabricated for use in imaging and other applications that require high diffraction efficiency with minimal chromatic aberrations and astigmatism across the bandwidth. A single VHOE acts as a mirror to reflect light (0.sup.th diffraction order) at the specified wavelength(s) and bandwidth with a principal ray at an angle equal to an angle of incidence of broadband light. A composite VHOE includes a complementary pair of input and output VHOEs each configured to diffract light into a non-zero N.sup.th order. The input and output VHOEs are positioned in parallel to and offset from each other such that the filtered N.sup.th order beam exits the composite lens on a path at the angle of incidence and parallel to the broadband light while suppressing the unwanted 0.sup.th order beam. The composite lens improves suppression of unwanted wavelengths while still achieving minimal chromatic aberration.

An optical device includes a lightguide having a first pair of external surfaces parallel to each other, and at least two sets of facets. Each of the sets including a plurality of partially reflecting facets parallel to each other, and between the first pair of external surfaces. In each of the sets of facets, the respective facets are at an oblique angle relative to the first pair of external surfaces, and at a non-parallel angle relative to another of the sets of facets. The optical device is particularly suited for optical aperture expansion.

There are provided an excellent diffractive optical element having a small amount of flare coloring and unaffected optical performance with a decrease in diffraction efficiency minimized and an optical system and an optical apparatus using the diffractive optical element. A diffractive optical element GD used in an optical system OL of a camera 1, which is an optical apparatus, and including a diffraction grating so that the diffractive optical element GD serves as a lens is so configured that the grating height h0 of the diffraction grating in a central region Ac around an optical axis Z is smaller than the grating height hmax of the diffraction grating in a peripheral region Ap.

A Pancharatnam Berry Phase (PBP) liquid crystal structure for adjusting or focusing light of a plurality of color channels emitted by a display of a head-mounted display (HMD) comprises a plurality of PBP active elements. Each PBP active element of the structure is configured to act as a half waveplate for light of a corresponding color channel, such that light of the corresponding color channel is adjusted by a predetermined amount. In addition, each PBP active element acts as a one waveplate for light of the remaining color channels, such that light of the remaining color channels passes through the PBP active element substantially unaffected. As such, the PBP structure is able to adjust incident light of the plurality of color channels uniformly in an apochromatic fashion.

To overcome the problem of a diffractive surface having a large, and often excessively large, amount of chromatic aberration, an optical system can use multiple cascaded or sequential diffractive surfaces that, combined, have a reduced amount of chromatic aberration. The optical system can be designed such that all rays traversing the optical system and passing through the diffractive surfaces have an equal optical path length. In the design process, the sets of rays are identified, and the designs of the diffractive surfaces are selected to produce the angular deviations to produce the identified ray paths. In one example, an achromatic lens formed as two annular optical surfaces can receive a collimated incident beam, redirect rays helically at the first surface toward the second surface, and redirect the rays at the second surface toward a focal point. The azimuthal redirection can decrease with increasing distance away from a central axis.