Irradiation (physical quantity)
The irradiation or irradiation is a physical quantity , mainly in the radiometry is used. It is the time-integrated irradiance and indicates the incident radiation energy of electromagnetic radiation per area. The symbol for irradiation is , the SI unit is joules per square meter (J / m 2 ). In the case of accumulating receivers (e.g. a photo plate ), the irradiation is a measure of the area-related potential of the radiation.
Irradiation should not be confused with fluence ; the latter is a particle-related quantity (unit of measurement m −2 ).
For a given location, the irradiation can be expressed as the radiation energy Q per area or, equivalent, as the integral of the irradiance E over the given period of time .
This size is also used in technical, scientific, but also medical areas:
- Irradiation instruments, lamps, UV lamps, material processing
- Skin diseases (see also 308 nm excimer laser )
- Lacquer and glue hardening, as well as the irradiation of radiation-sensitive "photo" lacquers (especially in microlithography when UV radiation is used)
- Drinking water treatment using UV light
- Energy measurement on pulsed lasers in which the physical effect is primarily determined by pulse energy and pulse duration.
The duration of the irradiation depends on the application and may be specified separately. The time interval to which the measurement relates can range from a few attoseconds (ultrashort pulse laser) to hours ( sunburn ) to years (fading of car paintwork). A reference variable for the time interval often emerges from the application.
Relationship with other radiometric quantities
|radiometric quantity||Symbol a)||SI unit||description||photometric equivalent b)||symbol||SI unit|
radiant power, radiant flux, radiant power
( watt )
|Radiant energy through time||
luminous flux, luminous power
( lumens )
irradiance, radiant intensity
|W / sr||Radiation flux through solid angles||
|cd = lm / sr
( candela )
|W / m 2||Radiation flux through the receiver surface||
|lx = lm / m 2
( lux )
emission current density, radiant exitance
|W / m 2||Radiation flux through the transmitter surface||
Specific light emission
|lm / m 2|
radiance, radiance, radiance
|W / m 2 sr||Radiant intensity through effective transmitter area||
||cd / m 2|
amount of radiation, radiant energy
( joules )
|by radiation transmitted energy||
Amount of light
luminous energy, quantity of light
|lm · s|
irradiation, radiant exposure
|J / m 2||Radiant energy through the receiver surface||
|1||Radiation flux through absorbed (mostly electrical) power||
(overall) luminous efficacy
|lm / W|
- Ludwig Bergmann , Clemens Schaefer : Optics . 9th edition. Walter de Gruyter, Berlin 1993, ISBN 3-11-012973-6 (textbook on experimental physics; 3).
- Commission Électrotechnique Internationale (CEI): Vocabulaire international de l'éclairage . Publication CIE No. 17.4. Central Bureau of the CEI. 1987. (Vocabulaire électrotechnique international 50 (845))
References and comments
- Although in English the “radiant exposure” is sometimes inconsistently referred to as “radiometric fluence” (fluence)