| 摘要 |
The present invention concerns a retroreflective device that is composed of an optical substrate (10) exhibiting an array of optical elements, the individual element pairs consisting of a focusing part, lens (12), and a reflecting part, mirror (13) and where the two parts have the shape of opposite spherical calottes with coinciding centres of curvature. The relation between the radii of curvature of the lens (12) and the mirror (13) has been adapted to the dispersion relation of the optical substrate (10) so that a preferred wavelength region is favoured. One characteristic following from this design is that the incident light defines the optical axis and that only the geometrical dimensions of the lens array limit the useable angles of incidence. |
