| 摘要 |
<p>A sign 1 for use as an aircraft emergency exit sign is configured to be visible to aircrew using night vision goggles. The sign includes an indicia layer 3, a filter layer over the indicia layer and a substrate layer 7. The indicia layer comprises a photoluminescent material, in particular a phosphorescent material. The photoluminescent material may emit light over a range of wavelengths including visible and near infrared parts of the spectrum. The filter layer 5 is arranged to selectively filter electromagnetic radiation from the indicia layer, in particular to reduce emission in the near infra-red part of the spectrum and to block emission in the infrared part of the spectrum. The light from the sign is visible to the unaided eye and also to aircrew wearing night vision goggles without causing flaring or blooming.</p> |
