This disclosure generally relates to retroreflective articles and methods of making such articles.

According to an example aspect of the present invention, there is provided an apparatus (201) comprising adjustable optical equipment (290), a position sensitive photodetector (280), at least one light emitter (220), and control circuitry (104) configured to cause the light emitter (220) and the adjustable optical equipment (290) to output from the apparatus (201) a divergent beam of light, to determine a location of a light signal on the position sensitive photodetector (280) and to cause at least one of the at least one light emitter (220) and the adjustable optical equipment (290) to output from the apparatus (201) a collimated beam of light to a direction selected based at least in part on the location of the light signal on the position sensitive photodetector (280).

According to one embodiment, a display device includes an optical element which transmits or reflects incident light, and a first reflective element including a first reflective portion and a second reflective portion. The first reflective portion retroreflects reflective light reflected on the optical element. The second reflective portion has an area less than an area of the first reflective portion and regularly reflects the reflective light.

A reflector for vehicles includes a reflective surface that contains an optical element to reflect light incident on the optical element according to specific reflection characteristics. The reflective surface is designed as a hologram element which has a grating structure in such a way that light incident on the hologram element is reflected according to the specific reflection characteristics.

A reflector for vehicles includes a reflective surface that contains an optical element to reflect light incident on the optical element according to specific reflection characteristics. The reflective surface is designed as a hologram element which has a grating structure in such a way that light incident on the hologram element is reflected according to the specific reflection characteristics.

An electronic keyboard using a camera, and more particularly, to an electronic keyboard using a camera, which includes a retroreflective film, a light source for irradiating light on to the retroreflective film, a camera for capturing light of a light source retroreflected from the retroreflective film, and an image processing means that analyzes the captured image to track the position of the reflected light source, to find a depressed state of the keyboard, and to generate a sound of an instrument corresponding to the depressed state.

An electronic keyboard using a camera, and more particularly, to an electronic keyboard using a camera, which includes a retroreflective film, a light source for irradiating light on to the retroreflective film, a camera for capturing light of a light source retroreflected from the retroreflective film, and an image processing means that analyzes the captured image to track the position of the reflected light source, to find a depressed state of the keyboard, and to generate a sound of an instrument corresponding to the depressed state.

The invention relates to an optical device for displaying a reticle or a target mark in a measuring or sighting telescope, comprising a reticle plate with a reticle disposed on one surface, a light source for illuminating this reticle, and the reticle plate has an entry surface for a beam path disposed to the side of the surface provided with the reticle, and at least one retroreflector is disposed on at least one light exit surface of the reticle plate, and a reflective layer of the retroreflector is directed towards the reticle plate.

A display device of one implementation of the present disclosure includes a light source, a retroreflective member disposed in a range which can be observed from a preset observation range of an observer, and a beam splitter which reflects light from the light source toward the retroreflective member and transmits the light reflected by the retroreflective member. The light source and the retroreflective member are positioned so that light specularly reflected by the retroreflective member does not enter the observation range.

A detection apparatus includes at least one processing unit, a light guide optical system configured to cause projected light to focus on a spatial image forming plane to form an image thereon, and a camera configured to detect an entry depth of a target object in a direction orthogonal to the spatial image forming plane and an entry position of the target object on the spatial image forming plane based on an image captured in such a manner that the spatial image forming plane is included within an angle of view, and the processing unit executes an operation associated with the entry position when the entry depth of the target object reaches a set depth.