Abstract: A method of machining a substrate to produce a cube corner element optical array. The method includes steps of directly machining a plurality of groove sets into a directly machinable substrate to form an array having a plurality of geometric structures including cube corner elements, and machining at least two of the groove sets along the same path in the substrate but at different depths of groove to produce a geometric structure side surface having both an optical portion and a non-optical portion.

Abstract: A retroreflective cube corner article which is a replica of a directly machined substrate in which a plurality of geometric structures including cube corner elements are machined in the substrate using only two sets of parallel grooves. At least two of the grooves in at least one of the groove sets are at a different groove depth.

Abstract: A method is disclosed for manufacturing a cube corner article comprising the steps of providing a machinable substrate material suitable for forming reflective surfaces, and creating a plurality of geometric structures including cube corner elements in the substrate. The step of creating the cube corner elements comprises directly machining at least three sets of parallel grooves in the substrate so that only one side of at least one groove in at least one groove set forms cube corner element optical surfaces.

Abstract: A method of manufacturing a cube corner article comprises machining first and second intersecting groove sets in a machinable substrate wherein the grooves in the first set are displaced by a distance d.sub.1 and the grooves in the second set are displaced by a distance d.sub.2. A third groove set comprising a plurality of parallel grooves displaced by a distance d.sub.3 is machined in the substrate, wherein d.sub.3 is different from d.sub.1 and d.sub.2. The machining steps result in a structured surface comprising an array of cube corner elements including at least two non-congruently shaped cube corner elements.

Abstract: Retroreflective elements, such as cube-corner elements or right triangular prisms containing cube-corners, are arranged on articles to define separation surfaces between the elements; in another embodiment, the elements are truncated cube-corners incorporating similar surfaces on the elements themselves. If the surfaces are transparent they will transmit light through the article, rendering it partially transparent and partially retroreflective. The surfaces may be flat or curved. Standard grooving techniques may be employed to construct the elements, using mold cutting tools having flattened or curved tips instead of V-shaped tips; alternatively, electroformed molds may be lapped to include the shape required to produce surfaces. The elements and surfaces may be embodied in sheeting materials or internally illuminated signs.

Abstract: Cube-corner retroreflectors having a rear surface configured with a cube-corner reflective element are made capable of reflecting light over a wide range of incident angles by placing a specularly reflective surface shaped as a negative of the cube-corner reflective element in closely spaced mating relationship with said rear surface.