The lux is the unit of illuminance: one lumen of luminous flux uniformly incident on one square metre gives one lux. It measures illumination arriving at a surface, rather than the surface's luminance or the source's luminous intensity.
For a small source of luminous intensity , normal incidence at distance gives when the source can be treated as a point and intervening losses are negligible. Thus a source gives at and at . A meter's sensor must be oriented consistently because tilting changes the projected collecting area.
"Lux" can refer to several different concepts depending on the context. Here are a few: 1. **Illumination/Light Measurement**: In scientific terms, "lux" is a unit of measurement for illuminance, which quantifies the amount of light that is received on a surface area. One lux is equal to one lumen per square meter. It is commonly used in fields related to lighting design and architecture.
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