APPARATUS FOR DISPLAYING A SUSPENDED IMAGE

摘要

The apparatus comprises an object (10) for display, a retro-reflector (12) receiving light from the object, a beam-splitter (14) in a path (16) for light from the object to the retro-reflector, and a Fresnel lens (20) (having no point of central symmetry) between the beam-splitter and the retro-reflector. The beam-splitter (14) makes an oblique angle to the direction of propagation of the light, such that it transmits some light and reflects the rest. Light from the beam-splitter passes through the lens (20) to the retro-reflector (12), which reflects it back through the lens to the beam-splitter. This retro-reflected light is reflected and/or transmitted by the beam-splitter to form a real image (18) suspended in space. The type of Fresnel lens used in the apparatus improves viewability because unwanted reflections from the surfaces of the lens are shifted such that they are no longer visible when viewing the suspended image.