The former is light intensity and light period, and the latter is light quality or light harmonic energy distribution. At the same time, light has particle properties and wave properties, that is, wave-particle duality. Light has visual attributes as well as energy attributes. The basic measurement method of photometry and colorimetry. ①Luminous flux, unit lumens lm, refers to the total amount of light emitted by a luminous body or light source per unit time, that is, luminous flux. ②Light intensity: symbol 1, unit candela cd, the luminous flux emitted by the luminous body or light source in a single solid angle in a specific direction. ③Illuminance: Symbol E, unit Lux lm/m2, the luminous flux of the luminous body illuminating the unit area of the illuminated object. ④ Luminance: Symbol L, unit nitre, cd/m2, luminous flux per unit solid angle per unit area in a specific direction. ⑤ Luminous efficiency: unit lumens per watt, lm/W, the ability of an electric light source to convert electrical energy into light, expressed by dividing the emitted luminous flux by the power consumption. ⑥Lamp efficiency: Also called light output coefficient, it is an important standard to measure the energy efficiency of lamps. It is the ratio between the light energy output by the lamp and the light energy output by the light source in the lamp. ⑦Average life: unit hour, refers to the number of hours when a batch of bulbs are damaged to 50% of the quantity. ⑧Economic life: unit hour, considering the damage of the bulb and the attenuation of the beam output, the comprehensive beam output is reduced to a specific number of hours. This ratio is 70% for outdoor light sources and 80% for indoor light sources such as fluorescent lamps. ⑨Color temperature: When the color of the light emitted by the light source is the same as the color of the black body at a certain temperature, the temperature of the black body is called the color temperature of the light source. The color temperature of the light source is different, and the light color is also different. The color temperature below 3300K has a stable atmosphere and a warm feeling; the color temperature is between 3000～5000K as the intermediate color temperature, which has a refreshing feeling; the color temperature above 5000K has a cold feeling. ⑩Color temperature color rendering: the color rendering index of the light source is indicated by the color rendering index, which indicates that the color deviation of the object under the light than the reference light (sunlight) illumination can more fully reflect the color characteristics of the light source.