Besaran cahaya

Satuan besaran cahaya

SI radiometry units
Quantity	Symbol	SI unit	Abbr.	Notes
Radiant energy	Q	joule	J	energy
Radiant flux		watt	W	radiant energy per unit time, also called radiant power
Radiant intensity	I	watt/steradian	W.sr−1	power per unit solid angle
Radiance	L	watt/steradian/square meter	W.sr−1.m−2	power per unit solid angle per unit projected source area called intensity in some other fields of study
Irradiance	E, I	watt/square meter	W.m−2	power incident on a surface, sometimes confusingly called intensity
Radiant exitance / Radiant emittance	M	watt/square meter	W.m−2	power emitted from a surface
Radiosity	J or J$\lambda$	watt/square meter	W.m−2	emitted plus reflected power leaving a surface
Spectral radiance	L$\lambda$ or Lv	watt/steradian/meter3 or watt/steradian/square meter/hertz	W.sr−1.m.−3 or W.sr−1.m−2.Hz−1	commonly measured in W.sr−1.m−2.nm−1
Spectral irradiance	E$\lambda$ or Ev	watt/meter3 or watt/square meter/hertz	W.m−3 or W.m−2.Hz−1	commonly measured in W.m−2.nm−1
SI photometry units
Quantity	Symbol	SI unit	Abbr.	Notes
Luminous energy	Qv	lumen second	lm.s	units are sometimes called talbots
Luminous flux	F	lumen (= cd.sr)	lm	also called luminous power
Luminous intensity	Iv	candela (=lumen/sr)	cd	an SI base unit
Luminance	Lv	candela/square meter	cd/m2	units are sometimes called "nits"
Illuminance	Ev	lux (= lm/m2)	lx	used for light incident on a surface
Luminous emittance	Mv	lux (= lm/m2)	lx	used for light emitted on a surface
Luminous efficacy		lumen/watt	lm/W	ratio of luminouos flux to radiant flux

Sumber Cahaya

• Radiasi panas (radiasi benda hitam)
  • bola lampu
  • matahari
  • partikel padat bercahaya dalam suhu tinggi(lihat api)
• emisi spektral atomik
  • laser dan maser
  • light emitting diode
  • lampu gas(lampu neon, lampu air raksa lamps dsb)
  • api dari gas
• percepatan dari partikal bebas bermuatan(biasanya sebuah elektron)
  • radiasi siklotron
  • Radiasi Bremsstrahlung
  • Radiasi Cherenkov
• kemoluminesens
• floresens
• fosforescence
  • tabung sinar katode
• bioluminesens
• sonoluminesens
• triboluminesens
• peluruhan radioaktif
• anihilasi partikel-antipartikel