| 摘要 |
Latent images on a screen (4) are polarisation encoded, so as to be visible only to a viewer (6) having suitable polarising means (7). The images may be projected via a liquid crystal display (4) having a rear polariser (3) and no front polariser. Images may further be colour encoded, with the polarising means (7) comprising suitably coloured tinted glasses. Alternatively, the images may be projected onto a window which has polarising material (7) on one side, such that they are visible from only one side of the window. Such a window can be used for advertising purposes, or to display an alarm signal which is not visible to an intruder or burglar. |
