The purpose of this standard is to give, in tabular form, the quantities and units of light and related electromagnetic radiation. When two symbols are given for the same quantity, without special dis inction, they can be used indifferently. SI units are given in bold; other units are given in common characters. The abbreviations "nI, de, en" respectively mean "Dutch, German, Englis " (is 639:1988). The definitions of the units are given in the NBN X 02-001 standard. SPECIAL REMARKS Most of the quantities given can be used for the entire range of electromagnetic radiation. With regard to light, especially photometric quantities are given. In several cases, the same symbol is used for a pair of energetic and luminous quantities which correspond to each other, it being understood that the indices e for energetic and v for vis ble, will be added each time a confusion between these quantities ris s occurring. For ionizing radiation however, see NBN X 02-110. In this standard, different quantities correspond to quantities which have the character of a spectral density in relation to the wavelength. The definition is given explicitly in 8, and the relationship to 7 is indicated in the "Definitions and Remarks" column. Other quantities having the character of a spectral density are indicated in the form of equations in the same column. We designate these quantities by adding the adjective “spectral” to the name of the initial quantity, for example volumetric spectral radiant energy. They are represented by adding the index X to the symbol of the initial quantity; this is considered as part of the symbol and indicates that the quantity has the dimensions of a derivative with respect to X. Quantities which have the character of a spectral density with respect to frequency or wave number are defined and designated in a similar way, the index X being replaced respectively by v or by cf. Quantities which have the character of a spectral density are also called dis ribution functions, for example wavelength dis ribution function, frequency dis ribution function. The adjective "spectral" is used to designate quantities which depend on the wavelength (or the frequency or the wave number) but which do not have the character of a spectral density, for example the spectral emis ivity (see 18.2). We usually indicate the functional dependence by writing X (or v or a) in parentheses as part of the symbol, for example e (X ).
NBN X 02-106-1990 history
1989NBN X 02-106-1990 Quantifies and units of light and related electromagnetic radiations