A unit of luminance (photometric brightness). One lambert is the luminance of a surface that emits or reflects one lumen per square centimeter. The lambert honors the German physicist Johann Lambert (1728-1777), who showed that the illuminance of a surface is inversely proportional to the square of the distance from the light source.
Refers to a unit of measure of light luminance.
Lambert-ian source or surface. A surface is referred to as a "Lambert" radiator or reflector (depending if its a primary or secondary source of light) if it is a perfectly diffusing surface.
A cgs unit of luminance (or photometric brightness) equal to one lumen, or 1/Ï€ candela per square centimeter. This luminance is produce by a blackbody source of luminous intensity 1 candela at a distance of 1 centimeter. The corresponding SI (or mks) unit is the apostilb, a unit 104 smaller produced by 1 candela at a distance of 1 m. The sun's disk at zenith at sea level under clear skies has a luminance of about 470 000 lambert, while that of a 60-watt, inside-frosted, tungsten-filament light bulb is about 38 lambert.
The lambert (symbol L) is an obsolete unit of luminance named for Johann Heinrich Lambert. A related unit of luminance, the footlambert, is still sometimes used in the lighting industry. The SI units is the candela per square metre (cd/m²).