The international unit is the candela (candela) abbreviation CD. Luminous intensity refers to the luminous flux emitted by the light source at a unit solid angle in a specified direction, that is, the luminous flux density radiated by the light source in a certain direction in space. Represents the light flux of the light source in the unit solid angle Light intensity is the abbreviation of luminous intensity. In photometry, it is derived from the unit CD of luminous intensity and the relationship between luminous intensity and luminous flux.ġlm is numerically equal to the luminous flux transmitted by a point light source with a luminous intensity of 1CD in a certain direction within a unit solid angle in that direction. The luminous flux of the former is ten times that of the latter. Since the visual function of human eyes to the light of different wavelengths is different, even if the radiation power of the light of different wavelengths is equal, the light flux is not equal.įor example, When the radiation power of green light with a wavelength of 5500 is the same as that of red light with a wavelength of 6500 Å. Only when x = 555nm does one watt of optical radiation power produces 683lm (lumens) of luminous flux. When p (x) is in watts, y (x) is in watts. If the radiant power of monochromatic light with a specific wavelength x is p(x), and the relative visual acuity function is vs(x), the luminous flux can be defined as y(x)=p(x)*vs(x) When X is other values, VX (x) is less than 1 We define the relative visual acuity VS (555) = 1 When the environment is bright, human eyes are most sensitive to light with wavelength x = 555nm (507nm when the place is dark). The sensitivity of human eyes to brightness is related to color and is not uniform in the whole visible light range.
Therefore, the optical radiation power of different wavebands is equal, but the luminous flux is different. The visual rate of human eyes to different wavelengths of light is different. That is, the product of the radiated energy in a certain frequency band and the relative visibility of the frequency band in unit time. It is also a physical quantity of vision caused by the human eye. Luminous flux is the radiant energy flux of a light source.
Luminous efficiency is the quotient of luminous flux and corresponding radiation flux, and the unit is LM / W. The luminous flux of the light beam reaching the surface is proportional to the number of particles hitting the surface in a time interval of 1 second.ġlm is equal to the luminous flux emitted by a point light source with a uniform luminous intensity of 1CD (candela) within a unit solid angle of 1sr (sphericity), i.e., 1 LM = 1 CD If you think of light as particles travelling through space (i.e., photons) Lumens (LM) are luminous flux units of the international system of units (SI) and the American system of units (as). The unit of luminous flux is LM (lumen) λ Is the spectral light apparent efficiency. Φ e λ Is the spectral density of the radiation flux. It describes the response of the human eyes to the light of different wavelengths.
It is obtained by summing up many test experiences for human eyes. V( λ): It is called the relative spectral sensitivity curve of the human eye, also known as the visual function curve. Traditionally, we call light waves below 380nm ultraviolet (UV) and light waves above 780nm infrared (IR). Λ： Wavelength, in fact, the human eye only reacts to visible light with a wavelength between 380nm and 780nm. V ( λ) It is the standard spectral luminous efficiency function specified by the International Commission on Illumination (CIE). Km is the maximum value of spectral luminous efficiency, equal to 683lm / W. The relationship between luminous flux and radiation flux is LED Light From ENE TECH Luminous flux refers to the amount of radiation flux derived from the evaluation of human visual characteristics according to the international standards, which is indicated by Φ (or Φ r) Express.
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