Most often mean quantity and quality of light perceived by the person by a light stream. For the comparison radiated by various light sources of particles experts use the technical parameters defining a possibility of use of lamps in any given field of activity.
Light stream it is considered to be one of power sizes which defines a radiation stream, its power. At the same time impact of particles on the light receiver having spectral sensitivity is considered. In daily occurrence the people face a concept of a light stream during operation of lamps more often.
The main characteristics on a light stream
The term "light stream" not only concretizes quantity of light particles, but also characterizes how light "turns out", is distributed. Experts united these two characteristics in the uniform term "photometric data", - they can be seen in technical data sheets of products, specifications where there are tables, schedules expressing intensity of distribution of light, plus, data on energy efficiency.
For assessment of a stream of light use the lumens which are considered as the main units of measure. However, it is not the only technical parameter characterizing real opportunities of a light source. That it is more correct to define efficiency of light experts apply other widespread concept – "useful light" which parameter of definition is illumination. It is measured in luxury (when the area - in square meters) or in foot-candelas (when the area – in square feet). For example, for rooms of office type where a large number of computers is located, it is recommended to try to obtain urovenya illumination from 300 lx. If you read, staying at home in a chair, then illumination has to be, at least, 500 lx, in the hall for lectures – 1000 lx, and here in the freight elevator enough and 50 lx.
Additional parameters
At experts such concept as "quality of light" which is related also to white and color light is widespread. The characteristics determining the saturation, constancy of a light stream apply to white, color light. Color temperature, the index of a color rendition carry only to white light. Color temperature is designed to stand on hind legs, radiations of white light, - cold (a bluish shade), neutral, warm (a reddish shade). The index of a color rendition defines a possibility of a source to transfer shades in comparison with the ideal light emitter. This parameter is determined by a scale where 100 it is equated to sunlight. For trading floors, production rooms, - everywhere where the color rendition is critical, the index has to be in limits 90-100. In office, educational rooms it is desirable that the value was equal to 70-90. In warehouses, other areas where the color rendition is not so important, it is enough of 50.