Measurement of illumination: theory and practice

Illuminance is a physical quantity characterized by the ratio of the flux of light incident on the surface to its area. And it is understood that the surface plane should be perpendicular to the axis of the light flux.

In addition to the hygienic value directly for humans, practically the measurement of illumination is used in animal husbandry to create the proper microclimate of premises, in breeding aquarium fish and plants, for growing indoor plants, for describing the characteristics of photo and video equipment, including outdoor video cameras .

Light sources

It is known that there is natural and artificial illumination. It is created by the corresponding light sources: the scattered light of the firmament, of course, the sun, as well as the reflected light of the moon, refers to the natural light. Artificial sources - various lamps (incandescent, gas-discharge, fluorescent), screens of TVs, computers.

Why you need to measure the illumination

Illumination is one of the most important hygienic indicators, on which human health directly depends. Measurement of illumination - the procedure included in the SanPin (sanitary rules and regulations), is necessarily performed in the workplace along with measurements of noise levels, vibration, dust and gas contamination.

Doctors say that inadequate lighting results in reduced visual acuity, fatigue, reduced concentration of attention and overall labor productivity, can even cause an accident. In animals and birds, a lack of illumination causes disruption in growth, development, poor body mass gain, a decrease in productivity (for farm animals), and the ability to reproduce.

What and in what units this physical quantity is measured

The measurement of illumination is carried out with a device called a luxmeter, this is a portable device that is a kind of photometer. Modern high-end devices are equipped with light filters. The unit of measurement of illumination in the system of international units (SI) is lux, which is equal to the ratio of 1 lumen to the square meter of the surface area. In lumens, the magnitude of the light flux is measured. In the US and English measurement systems, such units of luminosity as lumens per square foot, foot candela (the degree of illumination from a light source of 1 candel, spaced 1 foot from the surface) are used.

How is the illumination measured? This is done with a luxmeter, the meter of the latter should be in a horizontal position, place it in the necessary points of the room. For buildings and livestock complexes there are special control places of measurement prescribed in state standards. Use the instructions to the device, when using attachments, you need to take into account the attenuation coefficient, to which the result is multiplied. Then, according to various formulas, the minimum, average, maximum illumination, and also the coefficient of natural illumination are calculated.