Exposure (photography)#Photometric and radiometric exposure

Irradiation is a physical quantity, mainly used in radiometry. It indicates the radiation energy ( electromagnetic radiation ) per area. The SI unit of radiation dose is joules per square meter. So In accumulating receivers ( eg a photographic plate ) it is a measure of the relative to the area effect of radiation.

The symbol of the irradiation. It can be for a given location point as radiant energy Q per unit area, or equivalently, the integral of the irradiance E expressed over the given period of time.

The photometric equivalent of the irradiation is the exposure.

Will use this unit in technical, scientific, as well as medical fields:

• Skin diseases (cf. also the 308 nm excimer laser )
• Paint and Kleberhärtung
• Drinking water treatment by UV light
• Power measurements on pulsed lasers

The duration of the irradiation depends on the application and optionally specified separately. Here, the time interval, which is referred to the measurement of a few nanoseconds (pulse laser ) rich ( fading of car paints ) for hours (sunburn) to years. Often it appears a reference for the time interval from the application.