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Lumen maintenance compares the amount of light produced from a light source or from a luminaire when it is brand new to the amount of light output at a specific time in the future. For instance, if a luminaire produced 1,000 lumens of light when it was brand new and now produces 700 lumens of light after 30,000 hours, then it would have lumen ...
Scientists have discovered a mysterious pulsating light—and they don’t know what it could be. It pulses at a rate of about once every 21 minutes, and has been doing so since at least 1988.
Cryoluminescence, the emission of light when an object is cooled [6] (an example of this is wulfenite) Photoluminescence, a result of the absorption of photons Fluorescence, traditionally defined as the emission of light that ends immediately after the source of excitation is removed. As the definition does not fully describe the phenomenon ...
An LED strip, tape, or ribbon light is a flexible circuit board populated by surface-mount light-emitting diodes (SMD LEDs) and other components that usually comes with an adhesive backing. Traditionally, strip lights had been used solely in accent lighting, backlighting, task lighting, and decorative lighting applications, such as cove lighting .
November 1917 ad for an Ingersoll "Radiolite" watch, one of the first watches mass marketed in the USA featuring a radium-illuminated dial. Radium was discovered by Marie and Pierre Curie in 1898 [1] and was soon combined with paint to make luminescent paint, which was applied to clocks, airplane instruments, and the like, to be able to read them in the dark.
As of 2019, an autonomous light-powered high-accuracy quartz watch movement became commercially available which is claimed to be accurate to ± 1 second per year. [ 19 ] [ 20 ] Key elements to obtain the high claimed accuracy are applying an unusually shaped (for a watch) ( AT-cut ) quartz crystal operated at 2 23 or 8 388 608 Hz frequency ...
Since these materials have a high index of refraction, [note 1] design features of the devices such as special optical coatings and die shape are required to efficiently emit light. A LED is a long-lived light source, but certain mechanisms can cause slow loss of efficiency of the device or sudden failure.
The Black Watch was equipped with a red light emitting diode display, which illuminated only when the watchcase's surface was pressed; pressing one part of the case displayed hours and minutes, pressing another displayed minutes and seconds. The Black Watch was later available in grey and white, with these versions also having a date function.