Illuminance (E, Illuminance), unit lux is lx (formerly known as lux).
Definition: Illuminance produced by a uniform luminous flux of 1 lumen on a surface of 1 square meter
Explanation: The illuminance is for the location to be illuminated, but it is not related to the object being illuminated. A lumen of light, evenly projected onto an object of 1 m2, the illumination is 1 lx. The measurement of illuminance, using the illuminance meter, or the lux table, lux table. In fact, illuminance is the easiest to measure (relative to the other three), and the illuminance meter is very cheap to buy (several hundred dollars). In order to protect the eyes for life and work, there is a requirement for how much illumination is required in different places. For example, the machine room must be no less than 200 lx. The illuminance under the sun is very large and very common in nature, about 110,000 lx (self-test). I just measured it. The room is 3.8mx6.5m, there are 12 20W fluorescent tubes, and the desktop illumination is 400 lux.
Common illumination (lux):
Direct sunlight (noon), 110,000
Cloudy outdoor, 1000
Inside the mall, 500
Cloudy window room, 100
Under normal room lighting, 100
Under full moon, 0.2