| 摘要 |
Covert marking apparatus suitable for marking, for example, a rendezvous point, comprising a source 1 of monochromatic unmodulated radiation with which an object is illuminated at an intensity which is too low to be noticed in light of ambient radiation. Viewing of the scene through a suitable optical filter 3 which blocks radiation of different wavelength from that selected causes the illuminated object to stand out from the rest of the scene. |
