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Irradiance Profile

Peak irradiance is the highest power level of radiant energy at the work surface. This value is usually expressed as a single number-watts per centimeter squared (W/cm² ).

Irradiance profiles are a plot of the irradiance as a function of time. The irradiance is on the Y-axis plotted against time on the X-axis. An early instrument that provided irradiance profiles printed the results out on thermal paper (Profiling radiometer thermal paper printout).

Instruments are now available that can either transfer the reading to a computer or display the irradiance profile on an LED.

Typical irradiance profiles are illustrated.

Multiple Lamp Profile Example

All three lamps illustrated deliver the same total energy to a surface passing under them, but with different irradiance levels (note that the area under each curve is the same but the peak is very different). These bulbs have the same electrical power input ("watts per inch") but are of different diameters, the smallest yielding the highest peak.

Illustration of “Irradiance Profile”