Optical knowledge and terminology

[Light source type] : The light source can be divided into point light source, line light source and surface light source according to different light-emitting devices/principles. Typical point light sources include light-emitting diodes (LEDs), etc.; line light sources such as fluorescent tubes and cold cathode tubes ( CCFL); surface light source has OLED, TDEL / inorganic EL light-emitting device;

[Luminous flux]: The rate at which a light source emits light energy or the rate of light flow. It is the basic amount of the ability to illuminate a light source. The unit is Lumen. A l00 watt (w) bulb produces l750 lm, while a 40w cool white fluorescent tube produces 3l5 lm of luminous flux.

[Luminous intensity]: Abbreviated as luminosity, it means the luminous flux emitted from a solid angle (in Sr) of the light source, that is, the distribution of the luminous flux emitted by the light source or the lighting fixture in the selected direction of space, in units of candlelight (cd ). A light source with a luminous intensity of 1 cd emits a luminous flux of l2.57 lm.

[Illuminance]: The density of the received luminous flux on the illuminated surface, which can be measured by the luminous flux per unit area. The luminous flux of llm is evenly distributed over the surface of 1 m ^ 2 ( m 2 ), which produces 1 lux ( LUX , lX ) illuminance of 1 lm. The luminous flux falls on the surface of l ft 2 ( ft 2 ) with an illumination value of l ft. ( Footcandle , fC ). The illumination of the desktop and work surface should not be less than 150lX. The lighting in the living room is ideal for semi-direct lighting with a soft fit. The average illumination should be around l00lX. The power of reading and writing lamps can be larger, and the illumination should reach 200lX.

[Color temperature]: In most of our eyes, the light emitted by most light sources is called white light. In fact, the white light emitted by different light sources that appear to the naked eye will have different colors due to the color temperature. The more blue the light color, the higher the color temperature. The reddish color is the lower the color temperature. People's eyes are sometimes fooled by their own feelings, and the difference is not big, but in our photographs, we can see the most direct effects, such as photos taken under the eyes, may be blue and cold, and Pictures taken under the light (without turning on the flash) will have a noticeably warm orange-red color.

[Light source efficiency]: The efficiency of a light source is the value obtained by dividing the lumen of the light it emits by its power consumption. Light source efficiency (Lm/w) = lumens (Lm) / power consumption (W) is the amount of light emitted by each watt of power. The higher the value, the higher the efficiency of the light source and the more energy efficient. So efficiency is often an important factor we often have to consider.

[Category efficiency] : Incandescent bulb l5 / Quartz halogen lamp 25 /SL Energy-saving fluorescent bulb 65 / Mercury lamp 70 / Ordinary fluorescent tube 60