Measurement of illumination: theory and practice

Illumination is a physical quantity,characterized by the ratio of the flux of light incident on the surface to its area. And it is implied that the plane of the surface must be perpendicular to the axis of the light flux.

In addition to the hygienic value itselffor a person, 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.

Lighting sources

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

Why you need to measure light

Illumination is one of the most important hygienicindicators 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 on a par with measurements of noise levels, vibration, dust and gas contamination.

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

What and in what units is this physical quantity measured

Measurement of illumination is carried out with a device thatis called a luxmeter, it 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 American and English measuring systems, such units of measurement of illumination are used, as lumens per square foot, foot candela (the degree of illumination from a source of light force of 1 candel, spaced 1 foot from the surface).

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.