A vehicle surface 30, preferably wherein the vehicle is an aircraft, is described. The vehicle surface 30 comprises thereon and/or therein a set of retroreflectors 300, including a first retroreflector 300A, configured to reflect, at least in part, incident hostile light towards a source thereof.

A retroreflective sign comprising a rigid substrate with a pattern of cell walls formed of a polyurethane adhesive or two-part polyurea adhesive, and a polymeric sheet having a front face and a rear face, the rear face facing the substrate, the rear face comprising microprismatic reflective elements is disclosed. The polymeric sheet is adhered directly to the cell walls formed of the polyurethane adhesive or two-part polyurea adhesive while leaving an air gap between the microprismatic retroreflective elements and the rigid substrate in the cells. A method of making the retroreflective sign includes applying a polyurethane adhesive or two-part polyurea adhesive to a front side of a rigid substrate in a pattern defining cell walls; and prior to full curing of the polyurethane adhesive, laminating the front side of the rigid substrate a rear side of a polymeric sheet via the cell walls, the polymeric sheet comprising microprismatic elements.

A retroreflective sign comprising a rigid substrate with a pattern of cell walls formed of a polyurethane adhesive or two-part polyurea adhesive, and a polymeric sheet having a front face and a rear face, the rear face facing the substrate, the rear face comprising microprismatic reflective elements is disclosed. The polymeric sheet is adhered directly to the cell walls formed of the polyurethane adhesive or two-part polyurea adhesive while leaving an air gap between the microprismatic retroreflective elements and the rigid substrate in the cells. A method of making the retroreflective sign includes applying a polyurethane adhesive or two-part polyurea adhesive to a front side of a rigid substrate in a pattern defining cell walls; and prior to full curing of the polyurethane adhesive, laminating the front side of the rigid substrate a rear side of a polymeric sheet via the cell walls, the polymeric sheet comprising microprismatic elements.

A system for use in imaging in the air, including: an image source, a transflective mirror and a retroreflective element. Light emitted by the image source is irradiated onto the retroreflective element after being reflected by the transflective mirror, the light is reflected on the retroreflective element and emerges in an opposite direction along an original incident path, and after being transmitted by the transflective mirror, then forms a real image. A selective transmissive film is provided on a side of the transflective mirror facing the image source, and a phase delay optical element is provided on a side of the retroreflective element facing the transflective mirror such that first linearly polarized light incident on the retroreflective element from the transflective mirror becomes circularly polarized light after passing through the phase delay optical element.

A system for use in imaging in the air, including: an image source, a transflective mirror and a retroreflective element. Light emitted by the image source is irradiated onto the retroreflective element after being reflected by the transflective mirror, the light is reflected on the retroreflective element and emerges in an opposite direction along an original incident path, and after being transmitted by the transflective mirror, then forms a real image. A selective transmissive film is provided on a side of the transflective mirror facing the image source, and a phase delay optical element is provided on a side of the retroreflective element facing the transflective mirror such that first linearly polarized light incident on the retroreflective element from the transflective mirror becomes circularly polarized light after passing through the phase delay optical element.

A method for manufacturing a mold for a retroreflective element, the mold having plural polygonal faces having a common vertex, the method including the steps of: roughing of a polygonal face in which cutting is carried out such that a predetermined cutting amount in a finishing process is left with respect to a desired shape; and finishing of the polygonal face in which a blade portion is made to move relatively towards the vertex while an angle of relief of the blade portion is kept within 1 degree so as to carry out cutting of the predetermined cutting amount, wherein a depth of cut for each one-time cutting operation is 2 micrometers or smaller, and the movement of the blade portion is a combination of a motion towards the vertex and an oscillation.

Light reflective films have example application in hollow light guides and luminaires. The films comprise parallel channels distributed in layers or otherwise at different depths in the films. The channels provide interfaces at which light is reflected or redirected. The channels have a sufficient density that the film reflects a large proportion of light incident on a first face of the film. The channels may be filled with a gas such as air, a vacuum or a polymer for example. Methods for making films can include stacking thin sheets patterned with grooves, casting or extrusion.

A display element includes a plurality of display areas, each display area including a plurality of sub display areas, each sub display area including a plurality of cells. A boundary portion formed into a groove structure so as to surround the cells. A plurality of prism structures each having a triangular cross section are arranged in parallel to each other in the cells so as to extend linearly or in an arc, and the boundary portion includes a rib structure connected to both ends of one or more of the prism structures. A display area is to display different motifs, in response to one or more of the sub display areas changing an optical property to become reflective or transmissive in accordance with one or both of an orientation angle and an elevation angle of observation.

Display apparatus includes LEDs, bottom chassis to accommodate the LEDs; and reflective member disposed on the bottom chassis. The reflective member includes a reflective bottom portion, and a reflective inclined portion obliquely formed to face a rear surface of the display panel which includes first regions that respectively correspond to LEDs located adjacent to the reflective inclined portion, and second regions each provided between two neighboring first regions and has a reflective characteristic different from a reflective characteristic of a neighboring first region. Second regions and neighboring first regions are on the reflective inclined portion having a uniform incline angle with respect to a side edge of the reflective bottom portion, the first regions include a group of light adjusting members, and the group of light adjusting members of each of the first regions is disposed to correspond to one of the LEDs disposed adjacent to the reflective inclined portion.

The present disclosure includes in one instance an optical article comprising a data rich plurality of retroreflective meats that are configured in a spatially defined arrangement, where the plurality of retroreflective elements comprise retroreflective elements having at least two different retroreflective properties, and where data rich means information that is readily machine interpretable. The present disclosure also includes a system comprising the previously mentioned optical article, an optical system, and an inference engine for interpreting and classifying the plurality of retroreflective elements wherein the optical system feeds data to the inference engine.