Flux and luminous intensity


Lighting up the future

Luminous Flux (F)

The human eye's ability to send information captured through the eyes to the brain differs depending on the colour of the object being viewed. The light output, expressed in lumens (lm) is defined as the total amount of light emitted per second by a light source, taking into account the spectral sensitivity of human eye.

Colour Diodes


The LED we use at 3elamp are selected to optimize the effectiveness of our lamps emission, measured in lumens emitted per watt (lm/w).


A special case that should be known when comparing luminous flux (theoretical) is the existence of so-called optimal temperature of luminous flux in the discharge lamps (included the fluorescent tubes and lamps or FCL). These lamps are designed to provide optimum light output at a given temperature and thus, for each type of fluorescent lamp there is an optimum temperature in which the maximum luminous flux is provided (which is what is advertised).


This is because the mercury vapour pressure in the lamp's interior is defined by the temperature within it and the number of mercury atoms in a gaseous state that can interact with the electrons released will be insufficient when the ambient temperature is low (the flow light will be lower) and, conversely, when the outside temperature is higher than for the tube design, the number of mercury atoms in a gaseous state will be greater and an absorption of energy radiated will happens turning it in heat (and again, the light output will be lower).


Therefore, above or below the optimum temperature there will be significant losses of light flux (inefficiency). By contrast, LED lamps maintain a constant light beam across the range of operating temperature (-25 º C to XX ° C), avoiding the kind of losses suffered by fluorescent tubes with the mismatch between temperature and temperature of flow optimization bright.

Luminous Intensity (Iv)

Another aspect to consider when evaluating the implementation of a lamp is the light intensity.


Recall that the luminous flux (lumens) show the amount of light emitted by a light source (in all directions of space). To know how this luminous flux is distributed in each direction of space we have to know the luminous intensity.


So, by Luminous Intensity we understand the luminous flux emitted by a light source in a particular direction. The unit of measurement of luminous intensity is the candela (cd) and its value allows us to determine the concentration of light to be obtained in a certain direction.


Thus, with a smaller aperture beam, in degrees (°), we obtain greater concentration of light produced by a lamp and so, the lumens will focus on a smaller radius.


When we have reflector lamps, the magnitude which reports on the amount of radiated light by the lamp is the light intensity and not the flow, since the reflector makes the light be emitted in a certain direction.


With the LED lamps, optics can be designed to cover almost every need in lighting both ambience and functional.



If you want to know more about the different radiometric and photometric measurement and its units, you can take a look to the concise and really practical table that Instrument Systems provide in his website.

How does light, infrared and UV radiation interact with skin and eyes?

Light is essential to life on Earth and affects humans and other living organisms in various ways. The interaction of light with our skin and eyes influences our perception of warmth and cold. The changes in the level and colour of light throughout the day and across different seasons help the body regulate periods of rest and activity.


The way electromagnetic radiation interacts with matter depends on its wavelength and therefore its energy. Radiation of short wavelength (below 200 nm, such as UVCs) has high energy and can set off damaging chemical processes in living cells. If DNA is damaged in this way, it can lead to mutations and potentially induce cancer. Radiation of longer wavelength is usually harmless, although it can warm up the tissue exposed.


When radiation reaches the skin or the eyes, it can be reflected or it can penetrate the tissue and be absorbed or scattered in various directions. The fate of this radiation in the body depends on its wavelength

Visible light is usually scattered and is only strongly absorbed by some components such as pigments and blood. Pigments in specialized cells in the eye absorb visible radiation, triggering an electrical signal that travels through the optical nerve to the brain and allows us to see in colour.

Infrared radiation is not scattered but strongly absorbed by water – the main constituent of soft tissues – and this causes a heat sensation when the skin is exposed to sunlight.

Most ultraviolet radiation does not penetrate further than the upper layers of the skin (epidermis) as the human tissue absorbs the radiation very strongly. Although ultraviolet radiation has some beneficial effects such as helping production of vitamin D, in general it is considered to be harmful. This is because the absorbed energy not only produces heat but can also drive chemical reactions in the body. Most of these reactions are harmful and cause direct or indirect damage to proteins and DNA in the skin and eyes. Our skin is well adapted to the harmful effects of ultraviolet radiation and the damaged molecules and cells are usually repaired or replaced. Some people are particularly susceptible to ultraviolet and become sunburned even after extremely low exposures. Others show abnormal allergy-like skin reactions.

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