ISO 31-6 is the part of international standard ISO 31 that defines names and symbols for quantities and units related to light and related electromagnetic radiations. It is superseded by ISO 80000-7.
ISO 31-6 was initially published in 1980, and amended in 1985. It received a revision in 1992, which was amended in 1998. The standard was ultimately withdrawn in 2008, when it was replaced by ISO 80000-7.
Definitions The definitions of ISO 31-6, as defined in 1980, included:
Quantity Unit RemarksNameSymbolNameSymbolDefinitionfrequencyf, vhertzHz1 Hz = 1 s−1circular frequencyωreciprocal second, second to the power of minus ones−1radian per secondrad/swavelengthλmetremångströmÅ1 Å = 10−10 m10 Å = 1 nmwavenumber, repetencyσreciprocal metre, metre to the power of minus onem−1 The multiple cm−1 is often used.circular wavenumber, circular repetencykvelocity (speed) of propagation of electromagnetic waves in vacuoc, c0metre per secondm/s c = (2.99792458 ± 0.000000012) × 108 m/s.Sometimes c is used for the phase velocity in a medium, in which case c0 is used for the velocity in vacuo.radiant energyQ, W,(U, Qe)jouleJ1 J = 1 kg·m2/s2radiant energy densityw, (u)joule per cubic metreJ/m3spectral concentration of radiant energy density (in terms of wavelength), spectral radiant energy density (in terms of wavelength)wλjoule per metre to the fourth powerJ/m4radiant power, radiant energy fluxP, Φ, (Φe)wattW1 W = 1 J/sradiant energy fluence rateφ, ψwatt per square metreW/m2radiant intensityI, (Ie)watt per steradianW/sr
Notes
References