Lighting: radiance & irradiance measurements

Radiance measurements are carried out to determine the amount of radiant intensity per unit projected area [W/m²/sr] and are measured using a lens system as optics to target at diffuse surfaces [e.g. OLED or display panels]. Irradiance defines the amount of radiant flux incident on an object’s surface, typically expressed in power per unit of surface [W/m²]. Typically, irradiance measurements are carried out with a spectrometer equipped with a cosine corrector with a predefined diffuse measurement surface. These devices are capable of showing the spectral power distribution, as well as showing parameter such as colour, CCT, CRI, dominant & peak wavelength, PAR values, illuminance and luminous intensity. Irradiance measurements for large and high power light sources can also  be carried out by means of a spectroradiometer connected to an integrating sphere setup. Admesy offers complete solutions to carry out irradiance measurements for various types of light sources like for example LED or incandescent lamps. The table below shows an overview of Admesy’s spectroradiometers suitable for radiance and irradiance measurements including their spectral ranges. More information about the measurement procedure can be found in the application guide.

Rhea Hera Cronus 
 Radiance [W/m²/sr] Lens Lens Lens
 Irradiance [W/m²] Cosine corrector* Cosine corrector* Cosine corrector*
 Radiant intensity [W/sr] Cosine corrector* Cosine corrector* Cosine corrector*
 Spectral range



Custom WL range




 Low luminance  


*Instead of cosine correctors, integrating spheres can also be used to determine [spectral] irradiance and radiant intensity / illuminance and luminous intensity.