Abstract: Described herein are embodiments of fiber scanning systems and methods of scanning optical fibers. The disclosed systems and methods advantageously provide an improvement to the scanning range, the oscillation amplitude, and/or the maximum pointing angle for an optical fiber in a fiber scanning system by inducing a buckling of a portion of the optical fiber.

Abstract: Disclosed herein are various forms of prime polygon reflectors. In its various forms it is a device of predetermined geometric shape with aspects and scalable dimensions derived from a prime number and its mathematical square root. Geometric shapes based on the prime polygon have reflective surfaces that cause multiple internal reflections of incident waveform energy. In some forms the reflectors are truncated comprising arrayed truncated prime polygon reflectors. When used in conjunction with or absent absorptive media, coatings, or linings, they reject passage of electromagnetic energy within a band that varies with reflector size and can be used with or without a ground. Applications include but are not limited to acoustic, solar, and radar energy absorption, as well as passive barriers for reduction of electromagnetic radiation exposure, and bandwidth-tunable panels for architectural electromagnetic shielding.

Abstract: Various examples are provided related to amplified deformable mirrors (ADMs). In one embodiment, an ADM includes a deformable mirror and a flexible dielectric matrix deposited on a front side of the deformable mirror. A pathlength of a wavelength, ?0, of electromagnetic radiation passing through the dielectric matrix can be amplified by a distribution of dielectric particles embedded in the dielectric matrix.

Abstract: Provided is a near-eye display device including: a base substrate including first and second surfaces opposite to each other, an optical element array on the first surface, and a pixel island array and a sensor array that are on the second surface and are coupled to each other. The pixel island array emits first pixel light to the optical element array, such that the first pixel light passes through the optical element array and then reaches a human eye. The sensor array receives light of the first pixel light reflected by the human eye, determines a position of a pupil center of the human eye according to an intensity distribution of the reflected light, determines pixels corresponding to the position of the pupil center in the pixel island array, and controls the pixels to emit second pixel light.

Abstract: A laminate including: a first ply having a first surface and a second surface, where the first surface is an outer surface of the laminate; a second ply having a third surface facing the second surface and a fourth surface opposite the third surface, where the fourth surface is an inner surface of the laminate; an interlayer between the plies; and an enhanced p-polarized reflective coating positioned over at least a portion of a surface of the plies. When the laminate is contacted with radiation having p-polarized radiation at an angle of 60° relative to normal of the laminate, the laminate exhibits a LTA of at least 70% and a reflectivity of the p-polarized radiation of at least 10%. A display system and method of projecting an image in a heads-up display is also disclosed.

Abstract: A driving guidance system is provided for a motor vehicle having a windshield. The system includes an input device for generating an input signal associated with the movement of the motor vehicle, a road detection module for generating a road signal associated with a road geometry, and an ARHUD for generating a plurality of images upon the windshield. The system further includes a computer having a processor and a non-transitory computer readable medium storing instructions, such that the processor is programmed to receive the input signal and the road signal. The processor is further programmed to determine a predicted trajectory and a recommended trajectory of the motor vehicle along the road geometry based on the input signal and the road signal. The ARHUD is configured to generate the images upon the windshield and overlaid onto the road geometry to notify the driver of the predicted trajectory and the recommended trajectory.

Abstract: A system includes an image realisation device for forming a source image and projection optics for rendering a display image on a display screen, wherein the display image is a virtual image corresponding to the source image. The projection optics have an optical axis, and the image realisation device includes a first image realisation surface at a first distance along the optical axis and a second image realisation surface at a second, different distance along the optical axis. The first and second image realisation surfaces overlap, and the first and second image realisation surfaces include multiple regions, each region switchable between a transparent state and an image realisation state such that the source image may be formed on a region of the first or second image realisation surface and projected through the projection optics to render the display image on the display screen at a first or second apparent depth.

Abstract: An imaging system includes an image realisation device and projection optics for rendering a display image on a display screen. The image realisation device includes a first image realisation surface tilted relative to an optical axis such that a first point in a first region of the image realisation surface is at a first distance from the focal point of the projection optics and a second point in a second region of the image realisation surface is at a second different distance from the focal point of the projection optics. A first source image formed on the first region and projected through the projection optics renders the first display image on the display screen at a first apparent depth, and a second source image formed on the second region and projected through the projection optics renders the second display image on the display screen at a second apparent depth.

Abstract: An ocular optical system includes a light guiding prism that guides image light from a display element and an emission portion that emits the image light guided by the light guiding prism. The light guiding prism includes a plurality of sides arranged to surround a light path of the image light, and a reflection surface off which the image light is reflected to the emission portion. The plurality of sides include a first side that is arranged on an opposite side of a first plane including first and second optical axes and that is situated between the emission portion and the reflection surface, wherein the first optical axis is a portion of the image light before the image light is reflected off the reflection surface, and the second optical axis is a portion of the image light after the image light is reflected off the reflection surface.

Abstract: A spectacle lens for smartglasses can include at least one light source arrangement at the edge of the spectacle lens that emits coherent light, or at least one region at the edge of the spectacle lens for coupling in light from a light source arrangement that emits coherent light, or at least one light source arrangement that is embedded in the spectacle lens. A transparent or partly transparent display can provided to the spectacle lens such that coherent light emanating from the light source arrangement emits coherent light passing through the display or is reflected by the display. The wavefront of the coherent light is modulable in terms of its amplitude and/or its phase by an actuation of the display. A deformation device for deforming the wavefront of the coherent light before or after the modulation by the display can also be provided.

Abstract: The present invention is directed to wearable display technologies. More specifically, various embodiments of the present invention provide wearable augmented reality glasses incorporating projection display systems where one or more laser diodes are used as light source for illustrating images with optical delivery to the eye using transparent waveguides. In one set of embodiments, the present invention provides wearable augmented reality glasses incorporating projector systems that utilize transparent waveguides and blue and/or green laser fabricated using gallium nitride containing material. In another set of embodiments, the present invention provides wearable augmented reality glasses incorporating projection systems having digital lighting processing engines illuminated by blue and/or green laser devices with optical delivery to the eye using transparent waveguides.

Abstract: Provided are an optical element that can make the brightness of light emitted from a light guide plate uniform, a light guide element, and an image display device. The optical element includes a patterned cholesteric liquid crystal layer that is obtained by immobilizing a cholesteric liquid crystalline phase, in which the patterned cholesteric liquid crystal layer has a liquid crystal alignment pattern in which a direction of an optical axis derived from a liquid crystal compound changes while continuously rotating in at least one in-plane direction, and the patterned cholesteric liquid crystal layer has regions having different pitches of helical structures in a plane.

Abstract: An image light generation module includes a first display element configured to emit first image light, a second display element configured to emit second image light, a third display element configured to emit third image light, a combining prism configured to emit combined image light combined from the first image light, the second image light, and the third image light, and a first gap defining member that defines a first gap between the first display element and the combining prism, a second gap defining member that defines a second gap between the second display element and the combining prism, and a third gap defining member that defines a third gap between the third display element and the combining prism, in which at least one of the first gap, the second gap, and the third gap is different in size from another of the gaps.

Abstract: An optical measurement system includes a wearable device including a support assembly configured to be worn on a body of a user and a wearable assembly supported by the support assembly. The wearable assembly includes a plurality of light sources configured to emit a plurality of light pulses toward a target within the body of the user and a plurality of detectors each configured to receive a set of photons included in a light pulse included in the plurality of light pulses after the set of photons is scattered by the target. A position of the wearable assembly on the support assembly is adjustable.

Abstract: Improved wearable optics is disclosed. The wearable optics comprises a frame member and a lens. The wearable optics also includes circuitry within the frame member for enhancing the use of the wearable optics. A system and method in accordance with the present invention is directed to a variety of ways to enhance the use of eye-glasses. They are: (1) media focals, that is, utilizing the wearable optics for its intended purpose and enhancing that use by using imaging techniques to improve the vision of the user; (2) telecommunications enhancements that allow the eyeglasses to be integrated with telecommunication devices such as cell phones or the like; and (3) entertainment enhancements that allow the wearable optics to be integrated with devices such as MP3 players, radios, or the like.

Abstract: An augmented reality display system includes a first beam path for a foveal inset image on a holographic optical element, a second beam path for a peripheral display image on the holographic optical element, and pupil position tracking logic that generates control signals to set a position of the foveal inset as perceived through the holographic optical element, to determine the peripheral display image, and to control a moveable stage.

Abstract: A display device includes: a display unit including a plurality of display panels which displays images of different colors, a lens unit on the display unit, an optical path controller on the lens unit, where the optical path controller generates a composite image by superimposing the images displayed by the plurality of display panels with each other, and an output unit through which the composite image is displayed. The optical path controller controls optical paths of light incident on a first surface of the optical path controller facing the lens unit and light incident on a second surface of the optical path controller, which is opposite to the first surface, and provides the composite image to the output unit.

Abstract: An example wearable display system can be capable of determining a user interface (UI) event with respect to a virtual UI device (e.g., a button) and a pointer (e.g., a finger or a stylus) using a neural network. The wearable display system can render a representation of the UI device onto an image of the pointer captured when the virtual UI device is shown to the user and the user uses the pointer to interact with the virtual UI device. The representation of the UI device can include concentric shapes (or shapes with similar or the same centers of gravity) of high contrast. The neural network can be trained using training images with representations of virtual UI devices and pointers.

Abstract: Aspects of the present invention relate to methods and systems for measuring and managing the brightness of digital content in a field of view of a head-worn computer.

Abstract: A method, system, apparatus, and/or device to determine a condition of a user using a miniaturized collimator. The method, system, apparatus, and/or device may include: a carbon nanotube structure comprising a microtube that includes a set of aligned carbon nanotubes infiltrated by carbon and a through-channel, the carbon nanotube structure having a defined height to through-channel width aspect ratio, where: the defined height to through-channel width aspect ratio is based on a defined collimation to diffraction ratio; the set of aligned carbon nanotubes infiltrated by carbon is configured to absorb a first portion of light that travels through the through-channel at a first angle and impinges a side of a first through-channel portion; and the set of aligned carbon nanotubes infiltrated by the carbon is configured to allow a second portion of the light that enters the through-channel at a second angle to pass through the through-channel.

Abstract: A collimator includes a front lens sleeve, a clamping groove disposed on the front lens sleeve, a linking sleeve fastened on the clamping groove, a snapping groove disposed on the linking sleeve distal the front lens sleeve, a connection sleeve slidably connected to the snapping groove, a constraint sleeve disposed on the snapping groove, and a limit groove disposed on an inner surface of the constraint sleeve. The components cooperate with each other. The test chart is tilted relative to the optical axis of the lens and makes the test chart distributed at different distances along the axis. When using the camera to shoot the collimator, the clarity of different components reflects the relative focus position of the camera so as to detect the vehicle mounted camera.

Abstract: There is provided an optical element which includes a medium including a diffractive optical element (DOE). The medium is to receive a beam of light via a light guide. If the beam is incident upon the medium at an incidence angle within a first range of angles, the DOE is to direct a first portion of the beam out of the light guide along a second direction to form an outcoupled beam, and cause a second portion of the beam to propagate towards a surface of the light guide. Furthermore, if the incidence angle is within a second range of angles, the DOE is to split from the beam a third portion and a fourth portion each propagating towards the surface of the light guide. The third and fourth portions are to propagate along a third and a fourth direction respectively, which third direction is different than the fourth direction.

Abstract: A lens unit is provided, including a casing, a carrier, an optical lens, a first driving assembly, and a second driving assembly. The carrier is movably disposed in the casing, and the optical lens is disposed on the carrier. The first and second driving assemblies are provided to drive the carrier and the optical lens respectively to move along a first axis and a second axis relative to the casing. Specifically, when viewed along a direction perpendicular to an optical axis of the lens unit, the first and second driving assemblies do not overlap.

Abstract: An optical assembly includes a movable body that includes an optical module, a frame body radially outward of the movable body, and support portions that swingably support the movable body with respect to the frame body. Each of the support portions includes a guide portion between the movable body and the frame body to support the movable body, and a preload portion that pushes the guide portion toward the movable body. A radially inner end portion of the preload portion is connected to a radially outer end portion of the guide portion. A radially outer end portion of the preload portion is supported by the frame body. One of the movable body and the guide portion includes a first convex surface, and the other includes a first concave surface in contact with the first convex surface.

Abstract: Embodiments of the present disclosure disclose a camera module and a terminal device, and belongs to the field of optical image stabilization technologies. The camera module includes a lens optical device and an actuating part. The actuating part includes two movable blocks, fastening brackets located on two sides of each movable block, and a plurality of electrically controlled flexible members. The lens optical device is located between the two movable blocks, and is fastened on the two movable blocks. Each movable block is suspended on the fastening brackets by using elastic members. Each movable block and the fastening brackets on the two sides are connected by the electrically controlled flexible members. The present disclosure can improve an image stabilization effect of a terminal device in a photographing process.

Abstract: An actuator for a camera according to an embodiment includes a base having an inner space formed therein, a carrier provided inside the base and configured to move in at least one direction among an optical axis direction, a first direction perpendicular to the optical axis and a second direction perpendicular to the optical axis and the first direction; and a damper provided to the carrier or the base and configured to have a shape extending in two or more directions among the optical axis direction, the first direction and the second direction.

Abstract: A stereoscopic image display device includes a display 11 divided into sections 13 in each of which displayed are small images 12a to 12d each having a plurality of minute images 14, a shutter panel 16 disposed in front of the display 11 and including first mechanical shutters 17, which are arranged side by side in units of the minute image 14 and time-divisionally divide each section 13 per each of the small images 12a to 12d by switching on and off in units of the minute image 14, and an image forming panel 23 including image forming means 24 arranged side by side for forming an image from light rays from each of the small images 12a to 12d passing through the first mechanical shutters 17 when the first mechanical shutters 17 are on.

Abstract: Systems and methods are disclosed for augmented reality devices with prescription lenses. An example augmented reality device may include a frame and a lens coupled to the frame. The lens may include a prescription lens configured to refract light, the prescription lens having a first index of refraction value, a waveguide encapsulated in the prescription lens, the waveguide having a second index of refraction value, and a first coating layer disposed on a first side of the waveguide, the first coating layer having a third index of refraction value. The third index of refraction value may be less than the first index of refraction value, and the first index of refraction value may be less than the second index of refraction value.

Abstract: Disclosed are lenses and methods for verifying a lens with an induced aperture. The lenses can have a geometry that, among other things, maintains a centered position about a wearer's eye to prevent more than a permissible amount of movement of the lens relative to the eye. Further disclosed is a method for verifying the power profiles used with the lens, and a lens that can have a single power profile for a wide range of presbyopia.

Abstract: Contact lenses that have an ion-impermeable portion and an ion-permeable portion that are able to move on the eye without binding to the eye are described. The contact lenses exhibit an average ionoflux transmittance of at least 1.34×10?4 mm/min. One or more electronic components can be included in the contact lenses. Methods of making the contact lenses are also described.

Abstract: The present invention is directed to sunglasses with clear bifocals. The sunglasses with clear bifocals may comprise a pair of sunglasses having bifocal lenses that provide far distance correction through the top of the bifocal lenses and near distance correction through the bottom of the bifocal lenses. A portion of the bifocal lenses providing the far distance correction may be tinted to block sunlight and a portion of the bifocal lenses providing the near distance correction may be clear. As a non-limiting example, the pair of sunglasses may provide protection from bright sunlight while driving without interfering with the ability to read the instrument panel which is less brightly lit.

Abstract: An electronic case for electronic spectacles may include a base comprising a cavity formed therein. A first spectacle retention device may be located within the cavity. The first spectacle retention device may be configured to retain spectacles. An electrical control system may be included. An electrical connector may be configured to couple the electrical control system in electronic communication with the spectacles.

Abstract: A transmittance-variable device is provided in the present application. The present application provides a transmittance-variable device, which can be applied to various applications without causing problems such as a crosstalk phenomenon, a rainbow phenomenon or a mirroring phenomenon, while having excellent transmittance-variable characteristics.

Abstract: In one embodiment, an eyewear for a user includes an eyewear frame, electrical circuitry at least partially in the eyewear frame, and a touch sensitive input surface on the eyewear frame configured to provide an input to the electrical circuitry to perform a function via touching the touch sensitive input surface. In another embodiment, the eyewear includes a switch with at least two operational states. The operational states of the switch can be configured to be changed by sliding a finger across the touch sensitive input surface of the frame.

Abstract: Magnetic Bluetooth eyeglasses are revealed. A Bluetooth circuit module is mounted in a mounting space of a temple and provided with a built-in Bluetooth unit connected to mobile devices. The Bluetooth circuit module further includes a microphone, a speaker, a touch switch, and a power connection base. The temple is connected to a power supply device by magnetic attraction between first and second magnetic members while the power supply device is in contact with the power connection base of the Bluetooth circuit module. Thereby users are not bothered by wires while in use and the eyeglasses are more convenient to use. Moreover, the eyeglasses can still be used during charging process. Users only need to replace the power supply device with a new one already charged instead of taking off the whole eyeglasses. The eyeglasses which prevent moisture infiltration provide longer service life.

Abstract: Display panel and display device are provided. The display panel includes a plurality of pixels and a blocking metal wire. The pixel includes a display unit and a control unit driving the display unit. The display unit at least includes a heating element and a phase change material layer. The heating element includes a first connecting terminal and a second connecting terminal. The control unit includes a first signal terminal and a second signal terminal. The control unit includes at least one diode, which includes a diode semiconductor layer including a first electrode contact region, a second electrode contact region and a connecting region. The blocking metal wire covers the connecting region and is insulated from the connecting region. The blocking metal wire is electrically connected to each of the first signal terminal and the first signal source or to each of the second connecting terminal and the second signal source.

Abstract: Examples described herein relate to an optical coupler. The optical coupler may include a first optical waveguide base layer, a second optical waveguide base layer, an insulating layer disposed over at least a portion of both the first optical waveguide base layer and the second optical waveguide base layer, and a semiconductor material layer disposed over the insulating layer. Overlapping portions of the first optical waveguide base layer, the insulating layer, and the semiconductor material layer form a first optical waveguide, and overlapping portions of the second optical waveguide base layer, the insulating layer, and the semiconductor material layer form a second optical waveguide. Moreover, the optical coupler may include a plurality of metal contacts to receive one or more first biasing voltages to operate one of the first optical waveguide base layer and the second optical waveguide base layer in an accumulation mode.

Abstract: Structures for an optical power modulator and methods of fabricating a structure for an optical power modulator. A first waveguide core includes first and second sections. A second waveguide core includes a first section laterally adjacent to the first section of the first waveguide core and a second section laterally adjacent to the second section of the first waveguide core. An interconnect structure is formed over the first waveguide core and the second waveguide core. The interconnect structure includes first and second transmission lines. The first transmission line is physically connected within the interconnect structure to the first section of the first waveguide core. The second transmission line includes a first section physically connected within the interconnect structure to the second section of the first waveguide core and a second section adjacent to the first transmission line.

Abstract: A privacy display comprises a polarised output spatial light modulator, reflective polariser, plural polar control retarders and a polariser. In a privacy mode of operation, on-axis light from the spatial light modulator is directed without loss, whereas off-axis light has reduced luminance. Further, display reflectivity is reduced for on-axis reflections of ambient light, while reflectivity is increased for off-axis light. The visibility of the display to off-axis snoopers is reduced by means of luminance reduction and increased frontal reflectivity to ambient light. In a public mode of operation, the liquid crystal retardance is adjusted so that off-axis luminance and reflectivity are unmodified.

Abstract: An electronic device is provided. The electronic device includes a first electronic device unit and a second electronic device unit. The first electronic device unit includes a first substrate and a second substrate disposed opposite to the first substrate, and a portion of the first substrate protrudes outward a boundary of the second substrate in a first protruding direction perpendicular to a normal direction of the first substrate. The second electronic device unit is connected to the first electronic device unit and includes a third substrate and a fourth substrate disposed opposite to the third substrate, and a portion of the fourth substrate protrudes outward a boundary of the third substrate in a second protruding direction perpendicular to a normal direction of the third substrate. In addition, the portion of the first substrate and the portion of the fourth substrate each includes a grinded portion.

Abstract: According to one embodiment, a display device includes a display panel, a third transparent substrate, a light-emitting element, and a modulation element. The display panel includes a first transparent substrate, a second transparent substrate, a first liquid crystal layer of a polymer dispersed type held. The third transparent substrate has a first end portion. The light-emitting element is opposed to the first end portion. The modulation element includes a fourth transparent substrate and a fifth transparent substrate disposed between the light-emitting element and the first end portion, a second liquid crystal layer, and control electrodes for applying voltage to the second liquid crystal layer.

Abstract: A display element according to an embodiment of the present technology includes an optical control layer and a lens layer. The optical control layer modulates incident light for each pixel. The lens layer includes an incident surface, a plurality of refractive lenses disposed for each pixel, and a plurality of diffractive lenses disposed for each pixel to face the plurality of refractive lenses, and emits light incident from the incident surface and passing through the plurality of refractive lenses and the plurality of diffractive lenses to the optical control layer.

Abstract: The present disclosure can provide a stereoscopic display device and a method for manufacturing thereof. The stereoscopic display device includes first display areas and second display areas which are alternately provided, and further includes: a base substrate; a plurality of display components located on the base substrate of the first display area and the second display area; a first polarizing film, formed on one side of the display components of the first display area facing away from the base substrate; and a second polarizing film, formed on one side of the display components of the second display area facing away from the base substrate. The absorption axis direction of the first polarizing film is perpendicular to that of the second polarizing film.

Abstract: A display panel, a touch display panel, and a display device are provided. The touch display panel includes a first polarizer, a liquid crystal cell, and a backlight assembly, wherein a pencil hardness of the first polarizer is not less than 3H and not greater than 9H; the first polarizer is arranged at a side of the liquid crystal cell distal to the backlight assembly.

Abstract: An image display device which suppresses destruction of an image display panel due to static electricity carried by a phase difference film, and has excellent adhesiveness between the phase difference film and the image display panel even in a moisture-heat environment, and a circularly polarizing plate with a photosensitive adhesive. The image display device includes a circularly polarizing plate having a linear polarizer and a phase difference film, and an image display panel in this order from a viewing side, in which the phase difference film and the image display panel are bonded by a pressure-sensitive adhesive, the phase difference film has an optically anisotropic layer obtained by polymerizing a polymerizable liquid crystal composition containing at least one kind of polymerizable liquid crystal compound having a predetermined structure, and the pressure-sensitive adhesive contains a polymer having an acid value of 1 to 30 mgKOH/g and an antistatic agent.

Abstract: A display apparatus includes a light source emitting light; a light guide plate having a first surface and a second surface, and spreading light emitted from the light source therein to emit light through the first surface; and a local dimming unit configured to pass or scatter light emitted through the second surface of the light guide plate according to a position. The local dimming unit may include: an electro-optical layer configured to which optical properties change according to an electric field; and a plurality of electrodes positioned on the same plane to generate the electric field.

Abstract: Provided is a light-emitting device that makes it possible to emit, with high efficiency, light having higher uniformity. The light-emitting device includes a light source, a wavelength conversion unit, and a wall member. The light source is disposed on a substrate. The wavelength conversion unit includes a wavelength conversion member and a transparent member that contains the wavelength conversion member therein. The wavelength conversion member is disposed to face the light source in a thickness direction and converts first wavelength light from the light source to second wavelength light. The wall member is provided on a substrate and surrounds the light source in a plane that is orthogonal to the thickness direction. A region occupied by the wavelength conversion member is wider than a region surrounded by the wall member, and entirety overlaps with the region surrounded by the wall member in the thickness direction.

Abstract: Provided are a light guide film, a backlight unit, and a display device. Light guide portions are disposed in holes of a reflection plate on which light sources are disposed, and a light guide film is directly disposed on the reflection plate and the light guide portions to provide a light guiding function and a light shielding function. Therefore, a method of facilitating implementation of a backlight unit with a small thickness, which satisfies image quality is provided. Further, each of the light shielding patterns has different reflectances in different areas, thereby increasing the amount of light supplied to an area between light sources. Therefore, a backlight unit with a reduced number of light sources and improved image quality may be provided.

Abstract: A back light unit includes an array of light emitting diodes, at least two optical films positioned above the array of light emitting diodes, and a pair of brightness enhancement films positioned above the at least two optical films. A majority of the optical films are light splitting optical films having a plurality of light splitting microstructures on at least one surface thereof.

Abstract: According to one embodiment, a display device includes a first transparent substrate having a first side surface extending over a first area, a second area and a third area, a second transparent substrate opposed to the first transparent substrate in the third area, a polymer dispersed liquid crystal layer, a first wiring board mounted with a first light-emitting element in the first area, a second wiring board mounted with a second light-emitting element in the second area, a first terminal connected to a power supply in the first area, a second terminal connected to the second wiring board in the second area, and a first conductive layer arranged on the first side surface and connected to the first terminal and the second terminal.