1. Fields of application

Optical radiation is present in all areas of everyday life, industry and research. Depending on the field, references must meet a variety of needs: ease of use, robustness or precision, and in all cases confidence in the results.

Lighting is the most obvious area in which radiation measurements, and consequently calibration against references, are required. The need extends from the production of light sources to the well-being and safety of users. It should be noted that the quantities used in lighting are visual quantities, i.e. quantities integrating in a single value the entire spectrum of radiation weighted by the sensitivity of the average human eye, represented by the standardized curve V (λ) (§