We fabricated an emergency illumination panel by stacking two translucent pictures, one of which was painted with ink and the other with phosphors. When the panel was illuminated by backlight or room light, only the ink-printed picture was visible to the human eye and only the phosphorescent picture was visible in darkness. A two-way mirror was inserted between the two pictures both to prevent superimposition of the two images and to enhance phosphorescence. This phosphorescent emergency sign acted as an illuminator independently of electric power sources and provided sufficient brightness for reading newspaper headlines.
© 2004 Optical Society of America
(120.2040) Instrumentation, measurement, and metrology : Displays
(150.2950) Machine vision : Illumination
(160.2540) Materials : Fluorescent and luminescent materials
(330.1690) Vision, color, and visual optics : Color
(330.1720) Vision, color, and visual optics : Color vision
Mitsunori Saito and Hiroyuki Hashimoto, "Emergency Illumination Panel that Displays Different Pictures Depending on Room Brightness," Appl. Opt. 43, 3608-3613 (2004)