Methods, systems, and devices for free-space optical communications. An aircraft includes a flat optical communication terminal on an external surface of the aircraft, the flat optical communication terminal being configured to communicate with a ground station via a free-space optical communication link.

Technologies for silicon diffraction gratings are disclosed. In some embodiments, grating lines of the diffraction gratings may have several sub-lines that make up each grating line of the diffraction grating. The sub-lines may be sub-wavelength features. In some embodiments, several silicon diffraction gratings may be made from a wafer, such as a wafer with a diameter of 300 millimeters. The wafer may be etched precisely across the entire wafer, leading to a high yield of the diffraction gratings.

An optical lens device includes an optical substrate layer, an etched miniature-structure polarization layer and an etched miniature surface structure. The optical substrate layer is provided with a first surface and a second surface and a ray of light passes through the optical substrate layer. The etched miniature-structure polarization layer is provided on the first surface or the second surface of the optical substrate layer. The etched miniature surface structure is etched to form the miniature-structure etched polarization layer and provides a characteristic of optical polarization in the etched miniature-structure polarization layer. The etched miniature surface structure of the etched miniature-structure polarization layer provides an effect of optical polarization to the ray of light while passing through it.

In an optical system, a first optical section having positive power, a second optical section provided with a first diffractive element and having positive power, a third optical section having positive power, and a fourth optical section provided with a second diffractive element and having positive power are disposed along a light path of image light emitted from an image light generation device. A first intermediate image of the image light is formed between the first optical section and the third optical section, a pupil is formed in the vicinity of the third optical section, a second intermediate image of the image light is formed between the third optical section and the fourth optical section, and the fourth optical section collimates the image light to form an exit pupil. The first diffractive element and the second diffractive element are in a conjugate relation or a roughly conjugate relation.

A diffraction device includes a ZnS member and a ZnSe member coupled to the ZnS member, and a diffraction grating is provided on the ZnSe member.

An optical system having high optical performance, an optical apparatus including the optical system, and a method for manufacturing the optical system are provided. An optical system used for an optical apparatus such as a camera includes a front lens group including a diffraction lens having a diffraction surface and a rear lens group disposed on an image side of the front lens group. The optical system is configured so that an interval between the lens groups changes at magnification change. The optical system is also configured so that a condition expressed by a predetermined conditional expression is satisfied.

A method for optical sensing includes providing a mirror comprising a central reflective region surrounded by a peripheral glare-suppressing region. A beam of light from a laser light source is directed to reflect from the central region so as to pass through an output optic along an axis toward a target scene. The light returned from the target scene through the output optic is focused onto an optical sensor, via collection optics having a collection aperture surrounding the mirror.

The present disclosure relates to a method for producing an optical element, for example a lens, for example a headlight lens, for example for vehicle headlights or motor vehicle headlights, wherein an optical component part having an (optically effective) convex surface made of a first transparent optical material is provided and/or produced; a mold having a concave cavity and optical material is provided and/or produced; liquid transparent second optical material is placed into the concave cavity of the mold; and the optical component part having the convexly curved surface is pressed into the concave cavity of the mold such that an optically effective coating is formed on the convexly curved surface.

In various embodiments, one or more prisms are utilized in a wavelength beam combining laser system to regulate beam size and/or to provide narrower wavelength bandwidth.

A resonant waveguide grating includes a waveguiding layer and a plurality of subwavelength structures. The waveguiding layer, being in optical proximity to the plurality of subwavelength structures, is configured to guide at most ten wave-guided light modes. The plurality of subwavelength structures includes at least two adjacent grooves having a subwavelength distance between their groove centers being different than the subwavelength distance between the centers of two adjacent ridges. The plurality of subwavelength structures is configured to couple out of the waveguiding layer resonantly by diffraction, an outcoupled fraction of an incoupled portion of incident light. The outcoupled fraction is a diffracted part of an incident light beam. A diffractive optical combiner and a diffractive optical coupler, both include the resonant waveguide grating of the invention. A near-eye display apparatus includes at least the resonant waveguide grating of the invention.