Introduction to the Units of Illuminance Meters
Introduction to the unit of illuminance meter. Illuminance is the unit of an illuminance meter, and its physical meaning is the amount of light emitted per unit area. Illuminance is measured in lumens per square meter (Lm), also known as lux: 1Lux=1Lm/m2. From the above equation, it can be seen that Lm is the unit of luminous flux, defined as the amount of light radiated by pure platinum at a melting temperature (approximately 1770 ℃) with a surface area of 1/60 square meter within a solid angle of 1 spherical degree.
The explanation of the illuminance unit above seems theoretical and generally difficult to understand. In order to have a more intuitive understanding of the amount of illumination, let me give an example to illustrate:
A 100W incandescent lamp emits a total luminous flux of approximately 1200Lm. Assuming that the luminous flux is evenly distributed on a half spherical surface, the illuminance values at 1m and 5m from the light source can be calculated according to the following steps: the hemispherical area with a radius of 1m is 2 π × 12=6.28 m2, and the illuminance value at 1m from the light source is 1200Lm/6.28 m2=191Lux.
Similarly, the hemispherical area with a radius of 5m is 2 π × 52=157 m2, and the illuminance value at a distance of 5m from the light source is 1200Lm/157 m2=7.64Lux.
How much illumination does it usually have in our daily lives?
In summer, under the sunshine, it is about 100000 LUX;
The outdoor light intensity on cloudy days is 10000LUX;
The indoor daylight illumination is 100LUX;
The illumination on the desktop 60cm away from the 60W desk lamp is 300LUX;
The illumination in the live broadcast room of the TV station is 1000LUX;
At dusk, the room has a light intensity of 10LUX;
The illumination of night streetlights is 0.1LUX;
Candlelight illumination (at a distance of 20cm) is 10-15 LUX.
