Lux-meter

A lux-meter is a sensor making it possible to measure simply and quickly real, and nonsubjective illumination.
L' measuring unit is the lux.

Principle of operation

The modern lux-meters function according to the principle of a cell C.C.D or cell Photovoltaïque; an integrated circuit receives a certain quantity of light (photons constituting the “signal” which is an energy of radiation) and transforms it into electrical signal (analogical signal). This signal is visualized by the displacement of a needle, the lighting of a diode, the posting of a figure…
Une photoresistance associated with a Ohmmètre would play the same part.
Un filter of correction of spectrum makes it possible to prevent that the differences of spectrum does not distort measurement (the yellow light is for example more effective only the blue one to produce an electron starting from the energy of a package of photons)

The lux-meters can have several scales to adapt to weak or strong luminosities (until several tens of thousands of lux).
l' traditional unit of measurement is the lux, which corresponded to the light carried by a flame of candle 1 meter from distance.

Uses

It was initially used by the photographers or scenario writers, by the lighting engineers. It is used more and more by the energeticians to optimize the interior lighting (20 to 60% of electricity is consumed by lighting) or outside (which often wastes much energy). Are more rarely also used they to measure the luminosity of the sky in meteorology, to measure the light received on the ground in Forêt or in a Serre.
Depuis a few years, it is used by ecologists, astronomers or architects “HQE” (environmental High-quality) to establish quantitative indices of luminous Pollution or luminous Intrusion in order to them réduires by materials and adapted strategies of lighting.

See too

External bonds

ANPCN (National association for the Protection of the Night sky
IDA (International Darksky Association)
personal site

References

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